The Machilidae are a family of

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 belonging to the order

Archaeognatha The Archaeognatha are an order of apterygotes, known by various common names such as jumping bristletails. Among extant insect taxa they are some of the most evolutionarily primitive; they appeared in the Middle Devonian period at about the sa ...

(the bristletails). There are around 450 described species worldwide. These insects are wingless, elongated and more or less cylindrical with a distinctive humped

thorax The thorax (: thoraces or thoraxes) or chest is a part of the anatomy of mammals and other tetrapod animals located between the neck and the abdomen. In insects, crustaceans, and the extinct trilobites, the thorax is one of the three main di ...

and covered with tiny, close-fitting

scales Scale or scales may refer to: Mathematics * Scale (descriptive set theory), an object defined on a set of points * Scale (ratio), the ratio of a linear dimension of a model to the corresponding dimension of the original * Scale factor, a number ...

. The colour is usually grey or brown, sometimes intricately patterned. There are three "tails" at the rear of the

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 ...

: two cerci and a long central epiproct. They have large

compound eye A compound eye is a Eye, visual organ found in arthropods such as insects and crustaceans. It may consist of thousands of ommatidium, ommatidia, which are tiny independent photoreception units that consist of a cornea, lens (anatomy), lens, and p ...

s, often meeting at a central point. They resemble the

silverfish The silverfish (''Lepisma saccharinum'') is a species of small, primitive, wingless insect in the order Zygentoma (formerly Thysanura). Its common name derives from the insect's silvery light grey colour, combined with the fish-like appearanc ...

and the firebrat, which are from a different order,

Zygentoma Zygentoma are an order in the class Insecta, and consist of about 550 known species. The Zygentoma include the so-called silverfish or fishmoths, and the firebrats. A conspicuous feature of the order are the three long caudal filaments. The t ...

. Machilids undergo virtually no

metamorphosis Metamorphosis is a biological process by which an animal physically develops including birth transformation or hatching, involving a conspicuous and relatively abrupt change in the animal's body structure through cell growth and different ...

during their life cycles, and both

nymphs A nymph (; ; sometimes spelled nymphe) is a minor female nature deity in ancient Greek folklore. Distinct from other Greek goddesses, nymphs are generally regarded as personifications of nature; they are typically tied to a specific place, land ...

and adults are generally inconspicuous

herbivore A herbivore is an animal anatomically and physiologically evolved to feed on plants, especially upon vascular tissues such as foliage, fruits or seeds, as the main component of its diet. These more broadly also encompass animals that eat ...

s and

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. Many species are restricted to rocky

shore A coast (coastline, shoreline, seashore) is the land next to the sea or the line that forms the boundary between the land and the ocean or a lake. Coasts are influenced by the topography of the surrounding landscape and by aquatic erosion, su ...

lines, but some are found in well-vegetated habitats inland. They can move very fast and often escape by jumping considerable distances when disturbed. Like all Archaeognatha, machilids transfer sperm indirectly from male to female. Some species can spin silken threads that lead the female to the spermatophore. Other species can produce silken stalks on which they place droplets of sperm. There are no aquatic species, but some

littoral The littoral zone, also called litoral or nearshore, is the part of a sea, lake, or river that is close to the shore. In coastal ecology, the littoral zone includes the intertidal zone extending from the high water mark (which is rarely i ...

forms, such as '' Parapetrobius'' and '' Petrobius'', can swim. Their fossil records extends back into the Triassic with the genus '' Gigamachilis'' from the Middle Triassic of Italy and Switzerland, around 240 million years old.

Genera

Source: *'' Afrochilis'' Sturm, 2002 *'' Afromachilis'' Mendes, 1981 *'' Allopsontus'' Silvestri, 1911 *'' Bachilis'' Mendes, 1977 *'' Catamachilis'' Silvestri, 1923 *'' Charimachilis'' Wygodzinsky, 1939 *'' Coreamachilis'' Mendes, 1993 *'' Corethromachilis'' Carpenter, 1916 *'' Dilta'' Strand, 1911 *'' Graphitarsus'' Silvestri, 1908 *'' Haslundichilis'' Wygodzinsky, 1950 *'' Haslundiella'' Janetschek, 1954 *'' Heteropsontus'' Mendes, 1990 *'' Himalayachilis'' Wygodzinsky, 1952 *'' Janetschekilis'' Wygodzinsky, 1958 *'' Lepismachilis'' Verhoeff, 1910 *'' Leptomachilis'' Sturm, 1991 *'' Machilis'' Latrielle, 1832 *'' Machilopsis'' Olfers, 1907 *'' Mendeschilis'' Gaju, Mora, Molero & Bach, 2000 *'' Mesomachilis'' Silvestri, 1911 *'' Metagraphitarsus'' Paclt, 1969 *'' Metamachilis'' Silvestri, 1936 *'' Meximachilis'' Wygodzinsky, 1945 *'' Neomachilis'' Silvestri, 1911 *''† Onychomachilis'' Pierce, 1951 *'' Paramachilis'' Wygodzinsky, 1941 *'' Parapetrobius'' Mendes, 1980 *'' Parateutonia'' Verhoeff, 1910 *'' Pedetontinus'' Silvestri, 1943 *'' Pedetontoides'' Mendes, 1981 *'' Pedetontus'' Silvestri, 1911 *'' Petridiobius'' Paclt, 1970 *'' Petrobiellus'' Silvestri, 1943 *'' Petrobius'' Leach, 1817 *''Petromachilis'' Reilly, 1915 *''† Praemachilis'' Silvestri, 1904 *'' Praemachiloides'' Janetschek, 1954 *'' Praetrigoniophthalmus'' Janetschek, 1954 *'' Promesomachilis'' Silvestri, 1923 *'' Pseudocatamachilis'' Gaju & Bach, 1991 *'' Pseudomachilanus'' Paclt, 1969 *'' Silvestrichilis'' Wygodzinsky, 1950 *'' Silvestrichiloides'' Mendes, 1990 *'' Stachilis'' Janetschek, 1957 *'' Trigoniomachilis'' Stach, 1937 *'' Trigoniophthalmus'' Verhoeff, 1910 *'' Wygodzinskilis'' Janetschek, 1954

Gallery

File:Machilidae - Machilis species.jpg, ''Machilis'' species File:Machilidae Alfara.jpg, Machilidae species File:Petrobius maritimus 2010-06-02.jpg, ''Petrobius maritimus'' File:Petrobius brevistylis.jpg, ''Petrobius brevistylis''

References

*Chinery, Michael, ''Collins Guide to the Insects of Britain and Western Europe'' 1986 (Reprinted 1991) *McGavin, George C., ''Insects and Spiders'' 2004
Fauna Europaea
Archaeognatha Insect families {{Archaeognatha-stub