Opiliones
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The Opiliones (formerly Phalangida) are an
order Order, ORDER or Orders may refer to: * A socio-political or established or existing order, e.g. World order, Ancien Regime, Pax Britannica * Categorization, the process in which ideas and objects are recognized, differentiated, and understood ...
of
arachnid Arachnids are arthropods in the Class (biology), class Arachnida () of the subphylum Chelicerata. Arachnida includes, among others, spiders, scorpions, ticks, mites, pseudoscorpions, opiliones, harvestmen, Solifugae, camel spiders, Amblypygi, wh ...
s,
colloquially Colloquialism (also called ''colloquial language'', ''colloquial speech'', ''everyday language'', or ''general parlance'') is the linguistic style used for casual and informal communication. It is the most common form of speech in conversation am ...
known as harvestmen, harvesters, harvest spiders, or daddy longlegs (see below). , over 6,650 species of harvestmen have been discovered worldwide, although the total number of
extant Extant or Least-concern species, least concern is the opposite of the word extinct. It may refer to: * Extant hereditary titles * Extant literature, surviving literature, such as ''Beowulf'', the oldest extant manuscript written in English * Exta ...
species may exceed 10,000. The order Opiliones includes five suborders:
Cyphophthalmi Cyphophthalmi is a suborder of harvestmen, colloquially known as mite harvestmen. Cyphophthalmi comprises 36 genera, and more than two hundred described species. The six families are currently grouped into three infraorders: the Boreophthalmi, S ...
,
Eupnoi The Eupnoi are a suborder of harvestmen, with more than 200 genera, and about 1,700 described species. They consist of two superfamilies, the Phalangioidea with many long-legged species common to northern temperate regions, and the small group ...
,
Dyspnoi Dyspnoi is a suborder of harvestmen, currently comprising 43 extant genera and 356 extant species, although more species are expected to be described in the future. The eight families are currently grouped into three superfamilies: the Acropsopil ...
,
Laniatores Laniatores is the largest suborder of the arachnid order Opiliones with over 4,200 described species worldwide. The majority of the species are highly dependent on humid environments and usually correlated with tropical and temperate forest habit ...
, and
Tetrophthalmi Tetrophthalmi is an extinct suborder of Opiliones (commonly known as harvestmen or daddy-longlegs) that had both median and lateral eyes. First described in 2014, it is known from two extinct species. Phylogenetic analysis suggests that this e ...
, which were named in 2014. Representatives of each extant suborder can be found on all continents except
Antarctica Antarctica () is Earth's southernmost and least-populated continent. Situated almost entirely south of the Antarctic Circle and surrounded by the Southern Ocean (also known as the Antarctic Ocean), it contains the geographic South Pole. ...
. Well-preserved fossils have been found in the 400-million-year-old
Rhynie chert The Rhynie chert is a Lower Devonian Sedimentary rock, sedimentary deposit exhibiting extraordinary fossil detail or completeness (a Lagerstätte). It is exposed near the village of Rhynie, Aberdeenshire, Scotland; a second unit, the Windyfield ...
s of Scotland, and 305-million-year-old rocks in France. These fossils look surprisingly modern, indicating that their basic body shape developed very early on, and, at least in some taxa, has changed little since that time. Their
phylogenetic In biology, phylogenetics () is the study of the evolutionary history of life using observable characteristics of organisms (or genes), which is known as phylogenetic inference. It infers the relationship among organisms based on empirical dat ...
position within the Arachnida is disputed; their closest relatives may be camel spiders (
Solifugae Solifugae is an Order (biology), order of Arachnid, arachnids known variously as solifuges, sun spiders, camel spiders, and wind scorpions. The order includes more than 1,000 described species in about 147 genus, genera. Despite the common names, ...
) or a larger clade comprising horseshoe crabs, Ricinulei, and Arachnopulmonata (scorpions, pseudoscorpions, and Tetrapulmonata). Although superficially similar to and often misidentified as
spider Spiders (order (biology), order Araneae) are air-breathing arthropods that have eight limbs, chelicerae with fangs generally able to inject venom, and spinnerets that extrude spider silk, silk. They are the largest order of arachnids and ran ...
s (order Araneae), the Opiliones are a distinct order that is not closely related to spiders. They can be easily distinguished from long-legged spiders by their fused body regions and single pair of eyes in the middle of the
cephalothorax The cephalothorax, also called prosoma in some groups, is a tagma of various arthropods, comprising the head and the thorax fused together, as distinct from the abdomen behind. (The terms ''prosoma'' and ''opisthosoma'' are equivalent to ''cepha ...
. Spiders have a distinct abdomen that is separated from the cephalothorax by a constriction, and they have three to four pairs of eyes, usually around the margins of the cephalothorax.


Description

The Opiliones are known for having exceptionally long legs relative to their body size; however, some species are short-legged. As in all Arachnida, the body in the Opiliones has two tagmata, the
anterior Standard anatomical terms of location are used to describe unambiguously the anatomy of humans and other animals. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position pro ...
cephalothorax The cephalothorax, also called prosoma in some groups, is a tagma of various arthropods, comprising the head and the thorax fused together, as distinct from the abdomen behind. (The terms ''prosoma'' and ''opisthosoma'' are equivalent to ''cepha ...
or
prosoma The cephalothorax, also called prosoma in some groups, is a tagma of various arthropods, comprising the head and the thorax fused together, as distinct from the abdomen behind. (The terms ''prosoma'' and ''opisthosoma'' are equivalent to ''cepha ...
, and the posterior 10-segmented
abdomen The abdomen (colloquially called the gut, belly, tummy, midriff, tucky, or stomach) is the front part of the torso between the thorax (chest) and pelvis in humans and in other vertebrates. The area occupied by the abdomen is called the abdominal ...
or
opisthosoma The opisthosoma is the posterior part of the body in some arthropods, behind the prosoma ( cephalothorax). It is a distinctive feature of the subphylum Chelicerata (arachnids, horseshoe crabs and others). Although it is similar in most respects ...
. The most easily discernible difference between harvestmen and spiders is that in harvestmen, the connection between the cephalothorax and abdomen is broad, so that the body appears to be a single
oval An oval () is a closed curve in a plane which resembles the outline of an egg. The term is not very specific, but in some areas of mathematics (projective geometry, technical drawing, etc.), it is given a more precise definition, which may inc ...
structure. Other differences include the fact that Opiliones have no
venom Venom or zootoxin is a type of toxin produced by an animal that is actively delivered through a wound by means of a bite, sting, or similar action. The toxin is delivered through a specially evolved ''venom apparatus'', such as fangs or a sti ...
glands in their
chelicerae The chelicerae () are the arthropod mouthparts, mouthparts of the subphylum Chelicerata, an arthropod group that includes arachnids, horseshoe crabs, and sea spiders. Commonly referred to as "jaws", chelicerae may be shaped as either articulated ...
and thus pose no danger to humans. They also have no silk glands and therefore do not build webs. In some highly derived species, the first five abdominal segments are fused into a
dorsal Dorsal (from Latin ''dorsum'' ‘back’) may refer to: * Dorsal (anatomy), an anatomical term of location referring to the back or upper side of an organism or parts of an organism * Dorsal, positioned on top of an aircraft's fuselage The fus ...
shield called the scutum, which in most such species is fused with the
carapace A carapace is a dorsal (upper) section of the exoskeleton or shell in a number of animal groups, including arthropods, such as crustaceans and arachnids, as well as vertebrates, such as turtles and tortoises. In turtles and tortoises, the unde ...
. Some such Opiliones only have this shield in the males. In some species, the two posterior abdominal segments are reduced. Some of them are divided medially on the surface to form two plates beside each other. The second pair of legs is longer than the others and function as antennae or feelers. In short-legged species, this may not be obvious. The feeding apparatus ( stomotheca) differs from most arachnids in that Opiliones can swallow chunks of solid food, not only liquids. The stomotheca is formed by extensions of the coxae of the
pedipalp Pedipalps (commonly shortened to palps or palpi) are the secondary pair of forward appendages among Chelicerata, chelicerates – a group of arthropods including spiders, scorpions, horseshoe crabs, and sea spiders. The pedipalps are lateral to ...
s and the first pair of legs. Most Opiliones, except for Cyphophthalmi, have long been thought to have a single pair of camera-type eyes in the middle of the head, oriented sideways. Eyes in Cyphophthalmi, when present, are located laterally, near the ozopores. A 305-million-year-old fossilized harvestman with two pairs of eyes was reported in 2014. This find suggested that the eyes in Cyphophthalmi are not homologous to the eyes of other harvestmen. Many cave-adapted species are eyeless, such as the Brazilian '' Caecobunus termitarum'' ( Grassatores) from
termite Termites are a group of detritivore, detritophagous Eusociality, eusocial cockroaches which consume a variety of Detritus, decaying plant material, generally in the form of wood, Plant litter, leaf litter, and Humus, soil humus. They are dist ...
nests, '' Giupponia chagasi'' ( Gonyleptidae) from caves, most species of Cyphophthalmi, and all species of the Guasiniidae. However, recent work studying the embryonic development of the species '' Phalangium opilio'' and some Laniatores revealed that harvestman in addition to a pair of median eyes also have two sets of vestigial eyes: one median pair (homologous to those of
horseshoe crab Horseshoe crabs are arthropods of the family Limulidae and the only surviving xiphosurans. Despite their name, they are not true crabs or even crustaceans; they are chelicerates, more closely related to arachnids like spiders, ticks, and scor ...
s and
sea spider Sea spiders are marine arthropods of the class (biology), class Pycnogonida, hence they are also called pycnogonids (; named after ''Pycnogonum'', the type genus; with the suffix '). The class includes the only now-living order (biology), order P ...
s), and one lateral pair (homologous to facetted eyes of horseshoe crabs and insects). This discovery suggests that the neuroanatomy of harvestmen is more primitive than derived arachnid groups, like spiders and scorpions. It also showed that the four-eyed fossil harvestman previously discovered is most likely a member of the suborder
Eupnoi The Eupnoi are a suborder of harvestmen, with more than 200 genera, and about 1,700 described species. They consist of two superfamilies, the Phalangioidea with many long-legged species common to northern temperate regions, and the small group ...
(true daddy-longlegs). Harvestmen have a pair of prosomatic defensive scent glands ( ozopores) that secrete a peculiar-smelling fluid when disturbed. In some species, the fluid contains noxious quinones. They do not have
book lungs A book lung is a type of respiration organ used for atmospheric gas-exchange that is present in many arachnids, such as scorpions and spiders. Each of these organs is located inside an open, ventral-abdominal, air-filled cavity (atrium) and co ...
, and breathe through tracheae. A pair of spiracles is located between the base of the fourth pair of legs and the abdomen, with one opening on each side. In more active species, spiracles are also found upon the
tibia The tibia (; : tibiae or tibias), also known as the shinbone or shankbone, is the larger, stronger, and anterior (frontal) of the two Leg bones, bones in the leg below the knee in vertebrates (the other being the fibula, behind and to the outsi ...
of the legs. They have a gonopore on the ventral cephalothorax, and the copulation is direct as male Opiliones have a penis, unlike other arachnids. All species lay eggs. Typical body length does not exceed , and some species are smaller than 1 mm, although the largest known species, '' Trogulus torosus'' ( Trogulidae), grows as long as . The leg span of many species is much greater than the body length and sometimes exceeds and to in Southeast Asia. Most species live for a year.


Behavior

Many species are
omnivorous An omnivore () is an animal that regularly consumes significant quantities of both plant and animal matter. Obtaining energy and nutrients from plant and animal matter, omnivores digest carbohydrates, protein, fat, and fiber, and metabolize ...
, eating primarily small
insect Insects (from Latin ') are Hexapoda, hexapod invertebrates of the class (biology), class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body (Insect morphology#Head, head, ...
s and all kinds of plant material and
fungi A fungus (: fungi , , , or ; or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and mold (fungus), molds, as well as the more familiar mushrooms. These organisms are classified as one ...
. Some are
scavenger Scavengers are animals that consume Corpse decomposition, dead organisms that have died from causes other than predation or have been killed by other predators. While scavenging generally refers to carnivores feeding on carrion, it is also a he ...
s, feeding upon dead organisms, bird dung, and other fecal material. Such a broad range is unusual in arachnids, which are typically pure predators. Most hunting harvestmen ambush their prey, although active hunting is also found. Because their eyes cannot form images, they use their second pair of legs as antennae to explore their environment. Unlike most other arachnids, harvestmen do not have a sucking stomach or a filtering mechanism. Rather, they ingest small particles of their food, thus making them vulnerable to internal parasites such as
gregarine The gregarines are a group of Apicomplexan alveolates, classified as the Gregarinasina or Gregarinia. The large (roughly half a millimeter) parasites inhabit the intestines of many invertebrates. They are not found in any vertebrates. Gregarines ...
s. Although
parthenogenetic Parthenogenesis (; from the Greek + ) is a natural form of asexual reproduction in which the embryo develops directly from an egg without need for fertilization. In animals, parthenogenesis means the development of an embryo from an unfertiliz ...
species do occur, most harvestmen
reproduce sexually Sexual reproduction is a type of reproduction that involves a complex Biological life cycle, life cycle in which a gamete (haploid reproductive cells, such as a sperm or egg cell) with a single set of chromosomes combines with another gamete to p ...
. Except from small
fossorial A fossorial animal () is one that is adapted to digging and which lives primarily (but not solely) underground. Examples of fossorial vertebrates are Mole (animal), moles, badgers, naked mole-rats, meerkats, armadillos, wombats, and mole salamand ...
species in the suborder Cyphophthalmi, where the males deposit a
spermatophore A spermatophore, from Ancient Greek σπέρμα (''spérma''), meaning "seed", and -φόρος (''-phóros''), meaning "bearing", or sperm ampulla is a capsule or mass containing spermatozoa created by males of various animal species, especiall ...
,
mating In biology, mating is the pairing of either opposite-sex or hermaphroditic organisms for the purposes of sexual reproduction. ''Fertilization'' is the fusion of two gametes. '' Copulation'' is the union of the sex organs of two sexually repr ...
involves direct copulation. The females store the sperm, which is aflagellate and immobile, at the tip of her ovipositor. The eggs are fertilized during oviposition. The males of some species offer a secretion (nuptial gift) from their chelicerae to the female before copulation. Sometimes, the male guards the female after copulation, and in many species, the males defend territories. In some species, males also exhibit post-copulatory behavior in which the male specifically seeks out and shakes the female's sensory leg. This is believed to entice the female into mating a second time. The female lays her eggs shortly after mating to several months later. Some species build nests for this purpose. A unique feature of harvestmen is that some species practice parental care, in which the male is solely responsible for guarding the eggs resulting from multiple partners, often against egg-eating females, and cleaning the eggs regularly. Paternal care has evolved at least three times independently: once in the clade Progonyleptoidellinae + Caelopyginae, once in the Gonyleptinae, and once in the Heteropachylinae. Maternal care in opiliones probably evolved due to natural selection, while paternal care appears to be the result of sexual selection. Depending on circumstances such as temperature, the eggs may hatch at any time after the first 20 days, up to about half a year after being laid. Harvestmen variously pass through four to eight nymphal
instar An instar (, from the Latin '' īnstar'' 'form, likeness') is a developmental stage of arthropods, such as insects, which occurs between each moult (''ecdysis'') until sexual maturity is reached. Arthropods must shed the exoskeleton in order to ...
s to reach maturity, with most known species having six instars. Most species are
nocturnal Nocturnality is a ethology, behavior in some non-human animals characterized by being active during the night and sleeping during the day. The common adjective is "nocturnal", versus diurnality, diurnal meaning the opposite. Nocturnal creatur ...
and colored in hues of brown, although a number of diurnal species are known, some of which have vivid patterns in yellow, green, and black with varied reddish and blackish mottling and reticulation. Many species of harvestmen easily tolerate members of their own species, with aggregations of many individuals often found at protected sites near water. These aggregations may number 200 individuals in the
Laniatores Laniatores is the largest suborder of the arachnid order Opiliones with over 4,200 described species worldwide. The majority of the species are highly dependent on humid environments and usually correlated with tropical and temperate forest habit ...
, and more than 70,000 in certain
Eupnoi The Eupnoi are a suborder of harvestmen, with more than 200 genera, and about 1,700 described species. They consist of two superfamilies, the Phalangioidea with many long-legged species common to northern temperate regions, and the small group ...
.
Gregarious Sociality is the degree to which individuals in an animal population tend to associate in social groups (gregariousness) and form cooperative societies. Sociality is a survival response to evolutionary pressures. For example, when a mother was ...
behavior is likely a strategy against climatic odds, but also against predators, combining the effect of scent secretions, and reducing the probability of any particular individual being eaten. Harvestmen clean their legs after eating by drawing each leg in turn through their jaws.


Antipredator defences

Predators of harvestmen include a variety of animals, including some mammals, amphibians, and other arachnids like spiders and scorpions. Opiliones display a variety of primary and secondary defences against predation, ranging from morphological traits such as body armour to behavioral responses to chemical secretions. Some of these defences have been attributed and restricted to specific groups of harvestmen.


Primary defences

Primary defences help the harvestmen avoid encountering a potential predator and include
crypsis In ecology, crypsis is the ability of an animal or a plant to avoid observation or detection by other animals. It may be part of a predation strategy or an antipredator adaptation. Methods include camouflage, nocturnality, subterranean life ...
,
aposematism Aposematism is the Advertising in biology, advertising by an animal, whether terrestrial or marine, to potential predation, predators that it is not worth attacking or eating. This unprofitability may consist of any defenses which make the pr ...
, and
mimicry In evolutionary biology, mimicry is an evolved resemblance between an organism and another object, often an organism of another species. Mimicry may evolve between different species, or between individuals of the same species. In the simples ...
.


Crypsis

Particular patterns or colour markings on harvestmen's bodies can reduce detection by disrupting the animals' outlines or providing camouflage. Markings on legs can cause an interruption of the leg outline and loss of leg proportion recognition. Darker colourations and patterns function as
camouflage Camouflage is the use of any combination of materials, coloration, or illumination for concealment, either by making animals or objects hard to see, or by disguising them as something else. Examples include the leopard's spotted coat, the b ...
when they remain motionless.Gnaspini, P., Cavalheiro, A.J., 1998. Chemical and Behavioral Defensces of a Neotropical Cavernicolous Harvestman: Goniosoma spelaeum (Opiliones, Laniatores, Gonyleptidae). J. Arachnol. 26, 81–90. Within the genus '' Leiobunum'' are multiple species with cryptic colouration that changes over ontogeny to match the microhabitat used at each life stage. Many species have also been able to camouflage their bodies by covering with secretions and debris from the
leaf litter Plant litter (also leaf litter, tree litter, soil litter, litterfall, or duff) is dead plant material (such as leaves, bark, needles, twigs, and cladodes) that has fallen to the ground. This detritus or dead organic material and its constituen ...
found in their environments. Some hard-bodied harvestmen have epizoic
cyanobacteria Cyanobacteria ( ) are a group of autotrophic gram-negative bacteria that can obtain biological energy via oxygenic photosynthesis. The name "cyanobacteria" () refers to their bluish green (cyan) color, which forms the basis of cyanobacteri ...
and
liverworts Liverworts are a group of non-vascular plant, non-vascular embryophyte, land plants forming the division Marchantiophyta (). They may also be referred to as hepatics. Like mosses and hornworts, they have a gametophyte-dominant life cycle, in wh ...
growing on their bodies that suggest potential benefits for camouflage against large backgrounds to avoid detection by diurnal predators.


Aposematism and mimicry

Some harvestmen have elaborate and brightly coloured patterns or appendages which contrast with the body colouration, potentially serving as an aposematic warning to potential predators.Pomini, A.M., Machado, G., Pinto-da-Rocha, R., Macías-Ordóñez, R., Marsaioli, A.J., 2010. Lines of defence in the harvestman Hoplobunus mexicanus (Arachnida: Opiliones): Aposematism, stridulation, thanatosis and irritant chemicals. Biochem. Syst. Ecol. 38, 300–308. This mechanism is thought to be commonly used during daylight, when they could be easily seen by any predators. Other harvestmen may exhibit mimicry to resemble other species' appearances. Some Gonyleptidae individuals that produce translucid secretions have orange markings on their
carapace A carapace is a dorsal (upper) section of the exoskeleton or shell in a number of animal groups, including arthropods, such as crustaceans and arachnids, as well as vertebrates, such as turtles and tortoises. In turtles and tortoises, the unde ...
s. This may have an aposematic role by mimicking the colouration of glandular emissions of two other quinone-producing species. Mimicry (
Müllerian mimicry Müllerian mimicry is a natural phenomenon in which two or more well-defended species, often foul-tasting and sharing common predators, have come to mimicry, mimic each other's honest signal, honest aposematism, warning signals, to their mutuali ...
) occurring between Brazilian harvestmen that resemble others could be explained by
convergent evolution Convergent evolution is the independent evolution of similar features in species of different periods or epochs in time. Convergent evolution creates analogous structures that have similar form or function but were not present in the last comm ...
.


Secondary defences

Secondary defences allow for harvestmen to escape and survive from a predator after direct or indirect contact, including thanatosis,
freezing Freezing is a phase transition in which a liquid turns into a solid when its temperature is lowered below its freezing point. For most substances, the melting and freezing points are the same temperature; however, certain substances possess dif ...
, bobbing, autotomy, fleeing, stridulation, retaliation and chemical secretions.


Thanatosis

Some animals respond to attacks by simulating an apparent death to avoid either detection or further attacks. Arachnids such as spiders practise this mechanism when threatened or even to avoid being eaten by female spiders after mating. Thanatosis is used as a second line of defence when detected by a potential predator and is commonly observed within the
Dyspnoi Dyspnoi is a suborder of harvestmen, currently comprising 43 extant genera and 356 extant species, although more species are expected to be described in the future. The eight families are currently grouped into three superfamilies: the Acropsopil ...
and
Laniatores Laniatores is the largest suborder of the arachnid order Opiliones with over 4,200 described species worldwide. The majority of the species are highly dependent on humid environments and usually correlated with tropical and temperate forest habit ...
suborders, with individuals becoming rigid with legs either retracted or stretched.Eisner, T., Alsop, D., Meinwald, J., 1978. Secretions of Opilionids, Whip Scorpions and Pseudoscorpions, in: Arthropod Venoms, Handbook of Experimental Pharmacology / Handbuch Der Experimentellen Pharmakologie. Springer, Berlin, Heidelberg, pp. 87–99.Machado, G., Pomini, A.M., 2008. Chemical and behavioral defences of the neotropical harvestman Camarana flavipalpi (Arachnida: Opiliones). Biochem. Syst. Ecol. 36, 369–376.


Freezing

Freezing – or the complete halt of movement – has been documented in the family Sclerosomatidae. While this can mean an increased likelihood of immediate survival, it also leads to reduced food and water intake.Chelini, M.-C., Willemart, R.H., Hebets, E.A., 2009. Costs and benefits of freezing behaviour in the harvestman Eumesosoma roeweri (Arachnida, Opiliones). Behav. Processes 82, 153–159.


Bobbing

To deflect attacks and enhance escape, long-legged species – commonly known as daddy long-legs – from the
Eupnoi The Eupnoi are a suborder of harvestmen, with more than 200 genera, and about 1,700 described species. They consist of two superfamilies, the Phalangioidea with many long-legged species common to northern temperate regions, and the small group ...
suborder, use two mechanisms. One is bobbing, for which these particular individuals bounce their bodies. It potentially serves to confuse and deflect any identification of the exact location of their bodies. This can be a deceiving mechanism to avoid predation when they are in a large aggregation of individuals, which are all trembling at the same time.Escalante, I., Albín, A., Aisenberg, A., 2013. Lacking sensory (rather than locomotive) legs affects locomotion but not food detection in the harvestman Holmbergiana weyenberghi. Can. J. Zool. 91, 726–731. Cellar spiders (
Pholcidae The Pholcidae are a Family (biology), family of Araneomorphae, araneomorph spiders. The family contains more than 1,800 individual species of pholcids, including those commonly known as cellar spider, daddy long-legs spider, carpenter spid ...
) that are commonly mistaken for daddy long-legs (Opiliones) also exhibit this behavior when their webs are disturbed or even during courtship.


Autotomy

Autotomy is the voluntary amputation of an appendage and is employed to escape when restrained by a predator.Roth, V.D., Roth, B.M., 1984. review of appendotomy in spiders and other arachnids. Bull.-Br. Arachnol. Soc. Eupnoi individuals, more specifically sclerosomatid harvestmen, commonly use this strategy in response to being captured.Houghton, J.E., Townsend, V.R., Proud, D.N., 2011. The Ecological Significance of Leg Autotomy for Climbing Temperate Species of Harvestmen (Arachnida, Opiliones, Sclerosomatidae). Southeast. Nat. 10, 579–590.Guffey, C., 1998. Leg Autotomy and Its Potential Fitness Costs for Two Species of Harvestmen (Arachnida, Opiliones). J. Arachnol. 26, 296–302. This strategy can be costly because harvestmen do not regenerate their legs, and leg loss reduces locomotion, speed, climbing ability, sensory perception, food detection, and territoriality. Autotomised legs provide a further defence from predators because they can twitch for 60 seconds to an hour after detachment. This can also potentially serve as deflection from an attack and deceive a predator from attacking the animal. It has been shown to be successful against ants and spiders. The legs continue to twitch after they are detached because 'pacemakers' are located in the ends of the first long segment (femur) of their legs. These pacemakers send signals via the nerves to the muscles to extend the leg and then the leg relaxes between signals. While some harvestman's legs twitch for a minute, others have been recorded to twitch up to an hour. The twitching has been hypothesised to function as an evolutionary advantage by keeping the attention of a predator while the harvestman escapes.


Fleeing

Individuals that are able to detect potential threats can flee rapidly from attack. This is seen with multiple long-legged species in the Leiobunum clade that either drop and run, or drop and remain motionless. This is also seen when disturbing an aggregation of multiple individuals, where they all scatter.


Stridulation

Multiple species within the Laniatores and Dyspnoi possess stridulating organs, which are used as intraspecific communication and have also been shown to be used as a second line of defense when restrained by a predator.


Retaliation

Armored harvestmen in Laniatores can often use their modified morphology as weapons.Dias, B.C., Willemart, R.H., 2013. The effectiveness of post-contact defenses in a prey with no pre-contact detection. Zoology 116, 168–174.Segovia, J.M.G., Del-Claro, K., Willemart, R.H., 2015. Defences of a Neotropical harvestman against different levels of threat by the recluse spider. Behaviour 152, 757–773. Many have spines on their pedipalps, back legs, or bodies. By pinching with their chelicerae and pedipalps, they can cause harm to a potential predator. Also this has been proven to increase survival against recluse spiders by causing injury, allowing the harvestman to escape from predation.


Chemical

Harvestmen are well known for being chemically protected. They exude strongly odored secretions from their scent glands, called ozopores, that act as a shield against predators; this creates a strong and unpleasant taste, which is often their most effective defense. In ''Cyphophthalmi'' the scent glands release naphthoquinones, chloro-naphthoquinones and aliphatic methyl ketones, ''Insidiatores'' use nitrogen-containing substances,
terpenes Terpenes () are a class of natural products consisting of compounds with the formula (C5H8)n for n ≥ 2. Terpenes are major biosynthetic building blocks. Comprising more than 30,000 compounds, these unsaturated hydrocarbons are produced predomi ...
,
aliphatic In organic chemistry, hydrocarbons ( compounds composed solely of carbon and hydrogen) are divided into two classes: aromatic compounds and aliphatic compounds (; G. ''aleiphar'', fat, oil). Aliphatic compounds can be saturated (in which all ...
ketones In organic chemistry, a ketone is an organic compound with the structure , where R and R' can be a variety of carbon-containing substituents. Ketones contain a carbonyl group (a carbon-oxygen double bond C=O). The simplest ketone is acetone ( ...
, and phenolics, while ''Grassatores'' use alkylated phenolics and benzoquinones, and '' Palpatores'' use substances like naphthoquinones, methyl- and ethyl-ketones. These secretions have successfully protected the harvestmen against wandering spiders ( Ctenidae), wolf spiders (
Lycosidae Wolf spiders are members of the Family (biology), family Lycosidae (), named for their robust and agile hunting skills and excellent eyesight. They live mostly in solitude, hunt alone, and usually do not spin spider web, webs. Some are opportunis ...
) and '' Formica exsectoides'' ants. However, these chemical irritants are not able to prevent four species of harvestmen being preyed upon by the black scorpion '' Bothriurus bonariensis'' ( Bothriuridae). These secretions contain multiple volatile compounds that vary among individuals and clades.


Endangered status

All troglobitic species (of all animal taxa) are considered to be at least threatened in
Brazil Brazil, officially the Federative Republic of Brazil, is the largest country in South America. It is the world's List of countries and dependencies by area, fifth-largest country by area and the List of countries and dependencies by population ...
. Four species of Opiliones are on the Brazilian national list of endangered species, all of them cave-dwelling: '' Giupponia chagasi'', ''Iandumoema uai'', ''Pachylospeleus strinatii'' and ''Spaeleoleptes spaeleus''. Several Opiliones in Argentina appear to be vulnerable, if not endangered. These include ''Pachyloidellus fulvigranulatus'', which is found only on top of Cerro Uritorco, the highest peak in the Sierras Chicas chain (provincia de Cordoba) and ''Pachyloides borellii'' is in rainforest patches in northwest Argentina which are in an area being dramatically destroyed by humans. The cave-living ''Picunchenops spelaeus'' is apparently endangered through human action. So far, no harvestman has been included in any kind of a Red List in Argentina, so they receive no protection. ''Maiorerus randoi'' has only been found in one cave in the
Canary Islands The Canary Islands (; ) or Canaries are an archipelago in the Atlantic Ocean and the southernmost Autonomous communities of Spain, Autonomous Community of Spain. They are located in the northwest of Africa, with the closest point to the cont ...
. It is included in the Catálogo Nacional de especies amenazadas (National catalog of threatened species) from the Spanish government. '' Texella reddelli'' and '' Texella reyesi'' are listed as endangered species in the United States. Both are from caves in central
Texas Texas ( , ; or ) is the most populous U.S. state, state in the South Central United States, South Central region of the United States. It borders Louisiana to the east, Arkansas to the northeast, Oklahoma to the north, New Mexico to the we ...
. '' Texella cokendolpheri'' from a cave in central Texas and ''Calicina minor'', ''Microcina edgewoodensis'', ''Microcina homi'', ''Microcina jungi'', ''Microcina leei'', ''Microcina lumi'', and ''Microcina tiburona'' from around springs and other restricted habitats of central
California California () is a U.S. state, state in the Western United States that lies on the West Coast of the United States, Pacific Coast. It borders Oregon to the north, Nevada and Arizona to the east, and shares Mexico–United States border, an ...
are being considered for listing as endangered species, but as yet receive no protection.


Misconception

An
urban legend Urban legend (sometimes modern legend, urban myth, or simply legend) is a genre of folklore concerning stories about an unusual (usually scary) or humorous event that many people believe to be true but largely are not. These legends can be e ...
claims that the harvestman is the most
venom Venom or zootoxin is a type of toxin produced by an animal that is actively delivered through a wound by means of a bite, sting, or similar action. The toxin is delivered through a specially evolved ''venom apparatus'', such as fangs or a sti ...
ous animal in the world; however, it possesses fangs too short or a mouth too round and small to bite a human, rendering it harmless (the same myth applies to ''
Pholcus phalangioides ''Pholcus phalangioides'', commonly known as the cosmopolitan cellar spider, long-bodied cellar spider, or one of various types called a daddy long-legs spider, is a spider of the family Pholcidae. It was first described in 1775 by the Swiss En ...
'' and the crane fly, which are both also called a "daddy longlegs"). None of the known species of harvestmen have venom glands; their
chelicerae The chelicerae () are the arthropod mouthparts, mouthparts of the subphylum Chelicerata, an arthropod group that includes arachnids, horseshoe crabs, and sea spiders. Commonly referred to as "jaws", chelicerae may be shaped as either articulated ...
are not hollowed fangs but grasping claws that are typically very small and not strong enough to break human skin.


Research

Harvestmen are a scientifically neglected group. Description of new taxa has always been dependent on the activity of a few dedicated taxonomists.
Carl Friedrich Roewer Carl Friedrich Roewer (12 October 1881, in Neustrelitz – 17 June 1963) was a German arachnologist. He concentrated on harvestmen, where he described almost a third (2,260) of today's known species, but also almost 700 taxa of spiders and num ...
described about a third (2,260) of today's known species from the 1910s to the 1950s, and published the landmark systematic work (Harvestmen of the World) in 1923, with descriptions of all species known to that time. Other important taxonomists in this field include: *
Pierre André Latreille Pierre André Latreille (; 29 November 1762 – 6 February 1833) was a French zoology, zoologist, specialising in arthropods. Having trained as a Roman Catholic priest before the French Revolution, Latreille was imprisoned, and only regained hi ...
(18th century) *
Carl Ludwig Koch Carl Ludwig Koch (21 September 1778 – 23 August 1857) was a German entomologist and arachnologist. He was responsible for classifying a great number of spiders, including the Brazilian whiteknee tarantula and common house spider. He was born ...
, Maximilian Perty (1830s–1850s) * L. Koch, Tord Tamerlan Teodor Thorell (1860s–1870s) *
Eugène Simon Eugène Louis Simon (; 30 April 1848 – 17 November 1924) was a French naturalist who worked particularly on insects and spiders, but also on birds and plants. He is by far the most prolific spider Taxonomy (biology), taxonomist in history, ...
, William Sørensen (1880s–1890s) *James C. Cokendolpher, Raymond Forster, Clarence and Marie Goodnight, Jürgen Gruber, Reginald Frederick Lawrence, Jochen Martens,
Cândido Firmino de Mello-Leitão Cândido Firmino de Mello-Leitão (July 17, 1886 – December 14, 1948) was a Brazilian zoologist who is considered the founder of Arachnology in South America, publishing 198 papers on the Taxonomy (biology), taxonomy of Arachnida. He was als ...
(20th century) * Gonzalo Giribet, Adriano Brilhante Kury, Tone Novak (21st century) Since the 1990s, study of the biology and ecology of harvestmen has intensified, especially in
South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a considerably smaller portion in the Northern Hemisphere. It can also be described as the southern Subregion#Americas, subregion o ...
. Early work on the developmental biology of Opiliones from the mid-20th century was resurrected by Prashant P. Sharma, who established '' Phalangium opilio'' as a model system for the study of arachnid comparative genomics and evolutionary-developmental biology.


Phylogeny

Harvestmen are ancient
arachnid Arachnids are arthropods in the Class (biology), class Arachnida () of the subphylum Chelicerata. Arachnida includes, among others, spiders, scorpions, ticks, mites, pseudoscorpions, opiliones, harvestmen, Solifugae, camel spiders, Amblypygi, wh ...
s. Fossils from the
Devonian The Devonian ( ) is a period (geology), geologic period and system (stratigraphy), system of the Paleozoic era (geology), era during the Phanerozoic eon (geology), eon, spanning 60.3 million years from the end of the preceding Silurian per ...
Rhynie chert The Rhynie chert is a Lower Devonian Sedimentary rock, sedimentary deposit exhibiting extraordinary fossil detail or completeness (a Lagerstätte). It is exposed near the village of Rhynie, Aberdeenshire, Scotland; a second unit, the Windyfield ...
, 410 million years ago, already show characteristics like tracheae and sexual organs, indicating that the group has lived on land since that time. Despite being similar in appearance to, and often confused with, spiders, they are probably closely related to the
scorpion Scorpions are predatory arachnids of the Order (biology), order Scorpiones. They have eight legs and are easily recognized by a pair of Chela (organ), grasping pincers and a narrow, segmented tail, often carried in a characteristic forward cur ...
s,
pseudoscorpion Pseudoscorpions, also known as false scorpions or book scorpions, are small, scorpion-like arachnids belonging to the order Pseudoscorpiones, also known as Pseudoscorpionida or Chelonethida. Pseudoscorpions are generally beneficial to humans bec ...
s, and solifuges; these four orders form the clade Dromopoda. The Opiliones have remained almost unchanged morphologically over a long period. Indeed, one species discovered in China, ''Mesobunus martensi'', fossilized by fine-grained volcanic ash around 165 million years ago, is hardly discernible from modern-day harvestmen and has been placed in the extant family
Sclerosomatidae The Sclerosomatidae are a family (taxonomy), family of Opiliones, harvestmen with about 1,300 known species. One former subfamily has been recently removed to form a new family, Globipedidae.Kury, A.B. & J.C. Cokendolpher (2020) Chapter 9. A new ...
.


Systematics

The interfamilial relationships within Opiliones are not yet fully resolved, although significant strides have been made in recent years to determine these relationships. The following list is a compilation of interfamilial relationships recovered from several recent phylogenetic studies, although the placement and even monophyly of several taxa are still in question. * Suborder
Cyphophthalmi Cyphophthalmi is a suborder of harvestmen, colloquially known as mite harvestmen. Cyphophthalmi comprises 36 genera, and more than two hundred described species. The six families are currently grouped into three infraorders: the Boreophthalmi, S ...
Simon, 1879 (about 200 species) ** Infraorder Boreophthalmi Giribet, 2012 *** Family Sironidae Simon, 1879 *** Family Stylocellidae Hansen & Sørensen, 1904 ** Infraorder Scopulophthalmi Giribet, 2012 *** Family Pettalidae Shear, 1980 ** Infraorder Sternophthalmi Giribet, 2012 *** Family Troglosironidae Shear, 1993 ** Superfamily Ogoveoidea Shear, 1980 *** Family Neogoveidae Shear, 1980 *** Family Ogoveidae Shear, 1980 ** Infraorder (indet). *** Family Parasironidae Karaman, Mitov & Snegovaya, 2024 * Suborder
Eupnoi The Eupnoi are a suborder of harvestmen, with more than 200 genera, and about 1,700 described species. They consist of two superfamilies, the Phalangioidea with many long-legged species common to northern temperate regions, and the small group ...
Hansen & Sørensen, 1904 (about 1,800 species) ** Superfamily Caddoidea Banks, 1892 *** Family Caddidae Banks, 1892 ** Superfamily Phalangioidea Latreille, 1802 *** Family Globipedidae Kury & Cokendolpher, 2020 *** Family Neopilionidae Lawrence, 1931 *** Family Phalangiidae Latreille, 1802 *** Family Protolophidae Banks, 1893 *** Family
Sclerosomatidae The Sclerosomatidae are a family (taxonomy), family of Opiliones, harvestmen with about 1,300 known species. One former subfamily has been recently removed to form a new family, Globipedidae.Kury, A.B. & J.C. Cokendolpher (2020) Chapter 9. A new ...
Simon, 1879 * Suborder
Dyspnoi Dyspnoi is a suborder of harvestmen, currently comprising 43 extant genera and 356 extant species, although more species are expected to be described in the future. The eight families are currently grouped into three superfamilies: the Acropsopil ...
Hansen & Sørensen, 1904 (about 400 species) ** Superfamily Acropsopilionoidea Roewer, 1923 *** Family Acropsopilionidae Roewer, 1923 ** Superfamily Ischyropsalidoidea Simon, 1879 *** Family Ischyropsalididae Simon, 1879 *** Family Sabaconidae Dresco, 1970 *** Family Taracidae Schönhofer, 2013 ** Superfamily
Troguloidea Troguloidea is a superfamily of harvestman, harvestmen with 4 genera (2 extinct), found mostly in Europe, Asia, and North America (as of 2023). Description The superfamily Troguloidea was described by Carl Jakob Sundevall, Sundevall, with the ty ...
Sundevall, 1833 *** Family Dicranolasmatidae Simon, 1879 *** Family Nemastomatidae Simon, 1872 *** Family
Nipponopsalididae Nipponopsalididae is a family of harvestmen with three described species in one genus, ''Nipponopsalis'', which is found in East Asia. Name The genus name ''Nipponopsalis'' is a combination of ''Nippon'', meaning Japan, where the genus was first ...
Martens, 1976 *** Family Trogulidae Sundevall, 1833 * Suborder
Laniatores Laniatores is the largest suborder of the arachnid order Opiliones with over 4,200 described species worldwide. The majority of the species are highly dependent on humid environments and usually correlated with tropical and temperate forest habit ...
Thorell, 1876 (about 4,200 species) ** Infraorder Insidiatores Loman, 1900 *** Superfamily Travunioidea Absolon & Kratochvil, 1932 **** Family Cladonychiidae Hadži, 1935 **** Family Cryptomastridae Derkarabetian & Hedin, 2018 **** Family
Paranonychidae Paranonychidae is a family of armoured harvestmen in the order Opiliones The Opiliones (formerly Phalangida) are an Order (biology), order of arachnids, Common name, colloquially known as harvestmen, harvesters, harvest spiders, or daddy long ...
Briggs, 1971 **** Family
Travuniidae The Travuniidae are a small family of harvestman with little more than ten described species, within the suborder Laniatores. Description Travuniidae are at the most three millimeters long, with slender, unarmed legs and robust, strongly spined ...
Absolon & Kratochvil, 1932 *** Superfamily Triaenonychoidea Sørensen, 1886 **** Family Buemarinoidae Karaman, 2019 **** Family Lomanellidae Mendes & Derkarabetian, 2021 **** Family Synthetonychiidae Forster, 1954 **** Family Triaenonychidae Sørensen, 1886 ** Infraorder Grassatores Kury, 2002 *** Superfamily Assamioidea Sørensen, 1884 **** Family Assamiidae Sørensen, 1884 **** Family Pyramidopidae Sharma and Giribet, 2011 **** Family Suthepiidae Martens, 2020 **** Family Trionyxellidae Roewer, 1912 *** Superfamily Epedanoidea Sørensen, 1886 **** Family Epedanidae Sørensen, 1886 **** Family Petrobunidae Sharma and Giribet, 2011 **** Family Podoctidae Roewer, 1912 **** Family Tithaeidae Sharma and Giribet, 2011 *** Superfamily Gonyleptoidea Sundevall, 1833 **** Family Agoristenidae Šilhavý, 1973 **** Family Ampycidae Kury, 2003 **** Family Askawachidae Kury & Carvalho, 2020 **** Family Cosmetidae Koch, 1839 **** Family Cranaidae Roewer, 1913 **** Family Cryptogeobiidae Kury, 2014 **** Family Gerdesiidae Bragagnolo, 2015 **** Family Gonyleptidae Sundevall, 1833 **** Family Manaosbiidae Roewer, 1943 **** Family Metasarcidae Kury, 1994 **** Family Nomoclastidae Roewer, 1943 **** Family Otilioleptidae Acosta, 2019 **** Family Prostygnidae Roewer, 1913 **** Family Stygnidae Simon, 1879 **** Family Stygnopsidae Sørensen, 1932 *** Superfamily Phalangodoidea Simon, 1879 **** Family Phalangodidae Simon, 1879 *** Superfamily Samooidea Sørensen, 1886 **** Family Biantidae Thorell, 1889 **** Family Samoidae Sørensen, 1886 **** Family Stygnommatidae Roewer, 1923 *** Superfamily Sandokanoidea Özdikmen & Kury, 2007 **** Family Sandokanidae Özdikmen & Kury, 2007 *** Superfamily Zalmoxoidea Sørensen, 1886 **** Family Escadabiidae Kury & Pérez, 2003 **** Family Fissiphalliidae Martens, 1988 **** Family Guasiniidae Gonzalez-Sponga, 1997 **** Family Icaleptidae Kury & Pérez, 2002 **** Family
Kimulidae Kimulidae is a small neotropical family of the Opiliones, harvestman infraorder Grassatores with about thirty described species. (2007): Kimulidae. Kury & Pérez in Kury, 2003. In: Pinto-da-Rocha ''et al.'' 2007: 207ff Description These brown ha ...
Pérez González, Kury & Alonso-Zarazaga, 2007 **** Family Zalmoxidae Sørensen, 1886 The family Stygophalangiidae (one species, '' Stygophalangium karamani'') from underground waters in
North Macedonia North Macedonia, officially the Republic of North Macedonia, is a landlocked country in Southeast Europe. It shares land borders with Greece to the south, Albania to the west, Bulgaria to the east, Kosovo to the northwest and Serbia to the n ...
is sometimes misplaced in the Phalangioidea. It is not a harvestman.


Fossil record

Despite their long history, few harvestman fossils are known. This is mainly due to their delicate body structure and terrestrial habitat, making them unlikely to be found in sediments. As a consequence, most known fossils have been preserved within
amber Amber is fossilized tree resin. Examples of it have been appreciated for its color and natural beauty since the Neolithic times, and worked as a gemstone since antiquity."Amber" (2004). In Maxine N. Lurie and Marc Mappen (eds.) ''Encyclopedia ...
. The oldest known harvestman, from the 410-million-year-old Devonian Rhynie chert, displayed almost all the characteristics of modern species, placing the origin of harvestmen in the
Silurian The Silurian ( ) is a geologic period and system spanning 23.5 million years from the end of the Ordovician Period, at million years ago ( Mya), to the beginning of the Devonian Period, Mya. The Silurian is the third and shortest period of t ...
, or even earlier. A recent molecular study of Opiliones, however, dated the origin of the order at about 473 million years ago (Mya), during the Ordovician. No fossils of the
Cyphophthalmi Cyphophthalmi is a suborder of harvestmen, colloquially known as mite harvestmen. Cyphophthalmi comprises 36 genera, and more than two hundred described species. The six families are currently grouped into three infraorders: the Boreophthalmi, S ...
or
Laniatores Laniatores is the largest suborder of the arachnid order Opiliones with over 4,200 described species worldwide. The majority of the species are highly dependent on humid environments and usually correlated with tropical and temperate forest habit ...
much older than 50 million years are known, despite the former presenting a basal clade, and the latter having probably diverged from the Dyspnoi more than 300 Mya. Naturally, most finds are from comparatively recent times. More than 20 fossil species are known from the
Cenozoic The Cenozoic Era ( ; ) is Earth's current geological era, representing the last 66million years of Earth's history. It is characterized by the dominance of mammals, insects, birds and angiosperms (flowering plants). It is the latest of three g ...
, three from the
Mesozoic The Mesozoic Era is the Era (geology), era of Earth's Geologic time scale, geological history, lasting from about , comprising the Triassic, Jurassic and Cretaceous Period (geology), Periods. It is characterized by the dominance of archosaurian r ...
, and at least seven from the
Paleozoic The Paleozoic ( , , ; or Palaeozoic) Era is the first of three Era (geology), geological eras of the Phanerozoic Eon. Beginning 538.8 million years ago (Ma), it succeeds the Neoproterozoic (the last era of the Proterozoic Eon) and ends 251.9 Ma a ...
.


Paleozoic

The 410-million-year-old ''Eophalangium sheari'' is known from two specimens, one a female, the other a male. The female bears an
ovipositor The ovipositor is a tube-like organ used by some animals, especially insects, for the laying of eggs. In insects, an ovipositor consists of a maximum of three pairs of appendages. The details and morphology of the ovipositor vary, but typica ...
and is about long, whilst the male had a discernable penis. Whether both specimens belong to the same species is not definitely known. They have long legs, tracheae, and no median eyes. Together with the 305-million-year-old ''Hastocularis argus'', it forms the suborder
Tetrophthalmi Tetrophthalmi is an extinct suborder of Opiliones (commonly known as harvestmen or daddy-longlegs) that had both median and lateral eyes. First described in 2014, it is known from two extinct species. Phylogenetic analysis suggests that this e ...
, which was though to form the sister group to Cyphophthalmi. However, recent reanalysis of harvestman phylogeny has shown that ''E. sheari'' and ''H. argus'' are in fact members of the suborder
Eupnoi The Eupnoi are a suborder of harvestmen, with more than 200 genera, and about 1,700 described species. They consist of two superfamilies, the Phalangioidea with many long-legged species common to northern temperate regions, and the small group ...
, after it was discovered that living daddy-longlegs have the same arrangement of eyes as the fossils. ''Brigantibunum listoni'' from East Kirkton near
Edinburgh Edinburgh is the capital city of Scotland and one of its 32 Council areas of Scotland, council areas. The city is located in southeast Scotland and is bounded to the north by the Firth of Forth and to the south by the Pentland Hills. Edinburgh ...
in Scotland is almost 340 million years old. Its placement is rather uncertain, apart from it being a harvestman. From about 300 Mya, several finds are from the Coal Measures of North America and Europe. While the two described ''Nemastomoides'' species are currently grouped as Dyspnoi, they look more like Eupnoi. ''Kustarachne tenuipes'' was shown in 2004 to be a harvestman, after residing for almost one hundred years in its own arachnid order, the "Kustarachnida". Some fossils from the
Permian The Permian ( ) is a geologic period and System (stratigraphy), stratigraphic system which spans 47 million years, from the end of the Carboniferous Period million years ago (Mya), to the beginning of the Triassic Period 251.902 Mya. It is the s ...
are possibly harvestmen, but these are not well preserved.


Described species

* '' Eophalangium sheari'' Dunlop, 2004 (Tetrophthalmi) —
Early Devonian The Early Devonian is the first of three Epoch (geology), epochs comprising the Devonian period, corresponding to the Lower Devonian Series (stratigraphy), series. It lasted from and began with the Lochkovian Stage , which was followed by the Pr ...
( Rhynie,
Scotland Scotland is a Countries of the United Kingdom, country that is part of the United Kingdom. It contains nearly one-third of the United Kingdom's land area, consisting of the northern part of the island of Great Britain and more than 790 adjac ...
) * '' Brigantibunum listoni'' Dunlop, 2005 (Eupnoi?) —
Early Carboniferous Early may refer to: Places in the United States * Early, Iowa, a city * Early, Texas, a city * Early Branch, a stream in Missouri * Early County, Georgia * Fort Early, Georgia, an early 19th century fort Music * Early B, stage name of Jamaican d ...
( East Kirkton, Scotland) * '' Echinopustulus samuelnelsoni'' Dunlop, 2004 (Dyspnoi?) —
Upper Carboniferous Upper may refer to: * Shoe upper or ''vamp'', the part of a shoe on the top of the foot * Stimulant, drugs which induce temporary improvements in either mental or physical function or both * ''Upper'', the original film title for the 2013 found f ...
(Western
Missouri Missouri (''see #Etymology and pronunciation, pronunciation'') is a U.S. state, state in the Midwestern United States, Midwestern region of the United States. Ranking List of U.S. states and territories by area, 21st in land area, it border ...
, U.S.) * '' Eotrogulus fayoli'' Thevenin, 1901 (Dyspnoi: † Eotrogulidae) — Upper Carboniferous ( Commentry,
France France, officially the French Republic, is a country located primarily in Western Europe. Overseas France, Its overseas regions and territories include French Guiana in South America, Saint Pierre and Miquelon in the Atlantic Ocean#North Atlan ...
) * '' Hastocularis argus'' Garwood, 2014 (Tetrophthalmi) — Upper Carboniferous (
Montceau-les-Mines Montceau-les-Mines () is a Communes of France, commune in the Saône-et-Loire Departments of France, department in the Regions of France, region of Bourgogne-Franche-Comté in eastern France. It is the second-largest commune of the metropolitan C ...
, France) * '' Kustarachne longipes'' (Petrunkevitch, 1913) (Eupnoi) — Upper Carboniferous ( Mazon Creek, U.S.) * '' Kustarachne tenuipes'' Scudder, 1890 (Eupnoi) — Upper Carboniferous ( Mazon Creek, U.S.) * '' Nemastomoides elaveris'' Thevenin, 1901 (Dyspnoi: † Nemastomoididae) — Upper Carboniferous (Commentary, France) * '' Nemastomoides longipes'' Petrunkevitch, 1913 (Dyspnoi: † Nemastomoididae) — Upper Carboniferous (Mazon Creek, U.S.)


Mesozoic

* '' Burmalomanius circularis'' Bartel et al, 2023 (Podoctidae) —
Myanmar Myanmar, officially the Republic of the Union of Myanmar; and also referred to as Burma (the official English name until 1989), is a country in northwest Southeast Asia. It is the largest country by area in Mainland Southeast Asia and has ...
,
Burmese amber Burmese amber, also known as Burmite or Kachin amber, is amber from the Hukawng Valley in northern Myanmar. The amber is dated to around 100 million years ago, during the latest Albian to earliest Cenomanian ages of the mid-Cretaceous period. Th ...
(Cenomanian) * '' Petroburma tarsomeria'' Bartel et al, 2023 (Petrobunidae) —
Myanmar Myanmar, officially the Republic of the Union of Myanmar; and also referred to as Burma (the official English name until 1989), is a country in northwest Southeast Asia. It is the largest country by area in Mainland Southeast Asia and has ...
,
Burmese amber Burmese amber, also known as Burmite or Kachin amber, is amber from the Hukawng Valley in northern Myanmar. The amber is dated to around 100 million years ago, during the latest Albian to earliest Cenomanian ages of the mid-Cretaceous period. Th ...
(Cenomanian) * '' Mesodibunus tourinhoae'' Bartel et al, 2023 (Epedanidae) —
Myanmar Myanmar, officially the Republic of the Union of Myanmar; and also referred to as Burma (the official English name until 1989), is a country in northwest Southeast Asia. It is the largest country by area in Mainland Southeast Asia and has ...
,
Burmese amber Burmese amber, also known as Burmite or Kachin amber, is amber from the Hukawng Valley in northern Myanmar. The amber is dated to around 100 million years ago, during the latest Albian to earliest Cenomanian ages of the mid-Cretaceous period. Th ...
(Cenomanian) * '' indet'' Bartel et al, 2023 (Insidiatores indet.) —
Myanmar Myanmar, officially the Republic of the Union of Myanmar; and also referred to as Burma (the official English name until 1989), is a country in northwest Southeast Asia. It is the largest country by area in Mainland Southeast Asia and has ...
,
Burmese amber Burmese amber, also known as Burmite or Kachin amber, is amber from the Hukawng Valley in northern Myanmar. The amber is dated to around 100 million years ago, during the latest Albian to earliest Cenomanian ages of the mid-Cretaceous period. Th ...
(Cenomanian) etc. Bartel et al, 2023 report "These new records bring the total number of Burmese amber laniatorean species to ten" * '' Halitherses grimaldii'', a long-legged Dyspnoi with large eyes, was found in
Burmese amber Burmese amber, also known as Burmite or Kachin amber, is amber from the Hukawng Valley in northern Myanmar. The amber is dated to around 100 million years ago, during the latest Albian to earliest Cenomanian ages of the mid-Cretaceous period. Th ...
dating from approximately 100 Mya. It has been suggested that this may be related to the Ortholasmatinae (Nemastomatidae). Currently, no fossil harvestmen are known from the
Triassic The Triassic ( ; sometimes symbolized 🝈) is a geologic period and system which spans 50.5 million years from the end of the Permian Period 251.902 million years ago ( Mya), to the beginning of the Jurassic Period 201.4 Mya. The Triassic is t ...
. So far, they are also absent from the
Lower Cretaceous Lower may refer to: * ''Lower'' (album), 2025 album by Benjamin Booker * Lower (surname) * Lower Township, New Jersey *Lower Receiver (firearms) * Lower Wick Gloucestershire, England See also * Nizhny {{Disambiguation ...
Crato Formation The Crato Formation is a geologic formation (stratigraphy), formation of Early Cretaceous (Aptian) age in northeastern Brazil's Araripe Basin. It is an important Lagerstätten, Lagerstätte (undisturbed fossil accumulation) for palaeontology, pa ...
of Brazil, a
Lagerstätte A Fossil-Lagerstätte (, from ''Lager'' 'storage, lair' '' Stätte'' 'place'; plural ''Lagerstätten'') is a sedimentary deposit that preserves an exceptionally high amount of palaeontological information. ''Konzentrat-Lagerstätten'' preserv ...
that has yielded many other terrestrial arachnids. An unnamed long-legged harvestman was reported from the Early Cretaceous of Koonwarra, Victoria, Australia, which may be a Eupnoi.


Cenozoic

Unless otherwise noted, all species are from the
Eocene The Eocene ( ) is a geological epoch (geology), epoch that lasted from about 56 to 33.9 million years ago (Ma). It is the second epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), Era. The name ''Eocene'' comes ...
. * '' Trogulus longipes'' Haupt, 1956 (Dyspnoi: Trogulidae) — Geiseltal,
Germany Germany, officially the Federal Republic of Germany, is a country in Central Europe. It lies between the Baltic Sea and the North Sea to the north and the Alps to the south. Its sixteen States of Germany, constituent states have a total popu ...
* '' Philacarus hispaniolensis'' (Laniatores: Samoidae?) — Dominican amber * '' Kimula'' species (Laniatores:
Kimulidae Kimulidae is a small neotropical family of the Opiliones, harvestman infraorder Grassatores with about thirty described species. (2007): Kimulidae. Kury & Pérez in Kury, 2003. In: Pinto-da-Rocha ''et al.'' 2007: 207ff Description These brown ha ...
) — Dominican amber * '' Hummelinckiolus silhavyi'' Cokendolpher & Poinar, 1998 (Laniatores: Samoidae) — Dominican amber * ''
Caddo The Caddo people comprise the Caddo Nation of Oklahoma, a federally recognized tribe headquartered in Binger, Oklahoma. They speak the Caddo language. The Caddo Confederacy was a network of Indigenous peoples of the Southeastern Woodlands, who ...
dentipalpis'' (Eupnoi: Caddidae) —
Baltic amber Baltic amber or succinite is amber from the Baltic region, home of its largest known deposits. It was produced sometime during the Eocene epoch, but exactly when is controversial. It has been estimated that this forested region provided the re ...
* '' Dicranopalpus ramiger'' (Koch & Berendt, 1854) (Eupnoi: Phalangiidae) — Baltic amber * '' Opilio ovalis'' (Eupnoi: Phalangiidae?) — Baltic amber * '' Cheiromachus coriaceus'' Menge, 1854 (Eupnoi: Phalangiidae?) — Baltic amber * '' Leiobunum longipes'' (Eupnoi:
Sclerosomatidae The Sclerosomatidae are a family (taxonomy), family of Opiliones, harvestmen with about 1,300 known species. One former subfamily has been recently removed to form a new family, Globipedidae.Kury, A.B. & J.C. Cokendolpher (2020) Chapter 9. A new ...
) — Baltic amber * '' Histricostoma tuberculatum'' (Dyspnoi: Nemastomatidae) — Baltic amber * '' Mitostoma denticulatum'' (Dyspnoi: Nemastomatidae) — Baltic amber * '' Nemastoma incertum'' (Dyspnoi: Nemastomatidae) — Baltic amber * '' Sabacon claviger'' (Dyspnoi: Sabaconidae) — Baltic amber * '' Petrunkevitchiana oculata'' (Petrunkevitch, 1922) (Eupnoi: Phalangioidea) — Florissant Fossil Beds National Monument, USA (
Oligocene The Oligocene ( ) is a geologic epoch (geology), epoch of the Paleogene Geologic time scale, Period that extends from about 33.9 million to 23 million years before the present ( to ). As with other older geologic periods, the rock beds that defin ...
) * '' Proholoscotolemon nemastomoides'' (Laniatores: Cladonychiidae) — Baltic amber * '' Siro platypedibus'' (Cyphophthalmi: Sironidae) — Bitterfeld amber * '' Amauropilio atavus'' (Cockerell, 1907) (Eupnoi: Sclerosomatidae) — Florissant, USA (Oligocene) * '' Amauropilio lacoei'' (''A. lawei''?) (Petrunkevitch, 1922) — Florissant, USA (Oligocene) * '' Pellobunus proavus'' Cokendolpher, 1987 (Laniatores: Samoidae) — Dominican amber * '' Phalangium'' species (Eupnoi: Phalangiidae) — near
Rome Rome (Italian language, Italian and , ) is the capital city and most populated (municipality) of Italy. It is also the administrative centre of the Lazio Regions of Italy, region and of the Metropolitan City of Rome. A special named with 2, ...
,
Italy Italy, officially the Italian Republic, is a country in Southern Europe, Southern and Western Europe, Western Europe. It consists of Italian Peninsula, a peninsula that extends into the Mediterranean Sea, with the Alps on its northern land b ...
(
Quaternary The Quaternary ( ) is the current and most recent of the three periods of the Cenozoic Era in the geologic time scale of the International Commission on Stratigraphy (ICS), as well as the current and most recent of the twelve periods of the ...
)


Etymology

The Swedish naturalist and arachnologist
Carl Jakob Sundevall Carl Jakob Sundevall (22 October 1801 in Högestad – 2 February 1875) was a Sweden, Swedish zoologist. Sundevall studied at Lund University, where he received a Ph.D. in 1823. After traveling to East Asia, he studied medicine, graduating as a ...
(1801–1875) honored the naturalist
Martin Lister Martin Lister (12 April 1639 – 2 February 1712) was an English natural history, naturalist and physician. His daughters Anne Lister (illustrator), Anne and Susanna Lister, Susanna were two of his illustrators and engravers. J. D. Woodley, 'L ...
(1638–1712) by adopting Lister's term for this order, from Latin (“shepherd”), because these arachnids were known in Lister's days as ""; Lister characterized three species from England (although not formally describing them, being a pre-Linnaean work). In England, the Opiliones are often called "" or "". Folk-etymological explanations for this are numerous, such as that they appear during
harvest Harvesting is the process of collecting plants, animals, or fish (as well as fungi) as food, especially the process of gathering mature crops, and "the harvest" also refers to the collected crops. Reaping is the cutting of grain or pulses fo ...
season, or because of a superstitious belief that if one is killed there will be a bad harvest that year,Frank Cowan, ''Curious Facts in the History of Insects'', p.321 but these are unfounded. More likely, as in other European languages which call them a word meaning "cutter" or "scyther", the original explanation is that their oddly shaped legs look like tiny
sickle A sickle, bagging hook, reaping-hook or grasshook is a single-handed agricultural tool designed with variously curved blades and typically used for harvesting or reaping grain crops, or cutting Succulent plant, succulent forage chiefly for feedi ...
s or
scythe A scythe (, rhyming with ''writhe'') is an agriculture, agricultural hand-tool for mowing grass or Harvest, harvesting Crop, crops. It was historically used to cut down or reaping, reap edible grain, grains before they underwent the process of ...
s. The alternative name "shepherd spiders" is sometimes attributed to the assumption that Englishmen knew of the shepherds in the Landes region of France who traditionally used stilts to better observe their wandering flocks from a distance, and so were reminded of them by the long-legged arachnid, but is much more likely just an extension of this agricultural imagery, with the farmer's implement changed to a
shepherd's crook A shepherd's crook is a long and sturdy stick with a hook at one end, often with the point flared outwards, used by a shepherd to manage and sometimes catch sheep. In addition, the crook may aid in defending against attack by predators. Wh ...
rather than a reaping tool. Compare similar developments in the Dutch words for Opiliones: (literally meaning “ hay-wagon”) and in southern dialects (literally “cowherd”, one who herds cattle). English speakers may colloquially refer to species of Opiliones as "" or "granddaddy longlegs". However, this name is also used for two other distantly related groups of
arthropod Arthropods ( ) are invertebrates in the phylum Arthropoda. They possess an arthropod exoskeleton, exoskeleton with a cuticle made of chitin, often Mineralization (biology), mineralised with calcium carbonate, a body with differentiated (Metam ...
s: the crane flies of the superfamily
Tipuloidea A crane fly is any member of the dipteran superfamily Tipuloidea, which contains the living families Cylindrotomidae, Limoniidae, Pediciidae and Tipulidae, as well as several extinct families. "Winter crane flies", members of the family T ...
, as well as the cellar spiders of the family Pholcidae (which may be distinguished as ""), because of their similar appearance.


Further internal navigation links


References


External links

* * * Adriano Kury: National Museum of Rio de Janeir
Classification of Opiliones
A synoptic taxonomic arrangement of the order Opiliones, down to family-group level, including some photos of the families

Diagnostic photographs and information on North American harvestmen

Diagnostic photographs and information on European harvestmen * University of Aberdeen

(fossils)

{{Authority control Arachnid orders Extant Early Devonian first appearances Taxa named by Carl Jakob Sundevall