''Libinia spinosa'' is a majoid

crab Crabs are decapod crustaceans of the infraorder Brachyura (meaning "short tailed" in Greek language, Greek), which typically have a very short projecting tail-like abdomen#Arthropoda, abdomen, usually hidden entirely under the Thorax (arthropo ...

found in mud and sand bottoms of the Southwestern

Atlantic The Atlantic Ocean is the second largest of the world's five oceanic divisions, with an area of about . It covers approximately 17% of Earth's surface and about 24% of its water surface area. During the Age of Discovery, it was known for se ...

and

Pacific The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean, or, depending on the definition, to Antarctica in the south, and is bounded by the cont ...

oceans. It is a generalist feeder on organisms such as

algae Algae ( , ; : alga ) is an informal term for any organisms of a large and diverse group of photosynthesis, photosynthetic organisms that are not plants, and includes species from multiple distinct clades. Such organisms range from unicellular ...

sponge Sponges or sea sponges are primarily marine invertebrates of the animal phylum Porifera (; meaning 'pore bearer'), a basal clade and a sister taxon of the diploblasts. They are sessile filter feeders that are bound to the seabed, and a ...

cnidarian Cnidaria ( ) is a phylum under kingdom Animalia containing over 11,000 species of aquatic invertebrates found both in fresh water, freshwater and marine environments (predominantly the latter), including jellyfish, hydroid (zoology), hydroids, ...

mollusk Mollusca is a phylum of protostomic invertebrate animals, whose members are known as molluscs or mollusks (). Around 76,000 extant species of molluscs are recognized, making it the second-largest animal phylum after Arthropoda. The ...

polychaete Polychaeta () is a paraphyletic class of generally marine Annelid, annelid worms, common name, commonly called bristle worms or polychaetes (). Each body segment has a pair of fleshy protrusions called parapodia that bear many bristles, called c ...

crustacean Crustaceans (from Latin meaning: "those with shells" or "crusted ones") are invertebrate animals that constitute one group of arthropods that are traditionally a part of the subphylum Crustacea (), a large, diverse group of mainly aquatic arthrop ...

s, and small fish. It commonly engages in a

symbiotic Symbiosis (Ancient Greek : living with, companionship < : together; and ''bíōsis'': living) is any type of a close and long-term biolo ...

relationship with the medusa ''

Lychnorhiza lucerna ''Lychnorhiza lucerna'' or Marbled Jelly is a species of jellyfish in the order Rhizostomeae. It is found off the Atlantic coasts of South America. Description When small, ''Lychnorhiza lucerna'' has a hemispherical bell, but this becomes flatt ...

''.

Description

''Libinia spinosa'' is a member of the

superfamily

Majoidea The Majoidea are a Superfamily (taxonomy), superfamily of crabs which includes the various spider crabs. Taxonomy In "''A classification of living and fossil genera of decapod crustaceans''" De Grave and colleagues divided Majoidea into six fam ...

which are commonly known as the spider crabs. 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 ...

s of this organism can measure up to 89 mm and its leg span can be up to 568 mm. The number of median spines of ''Libinia spinosa'' can vary, with 7 being the most common number, but ''Libinia spinosa'' with 5, 8, and 10 median spines are also seen commonly. Testes are visibly flat, transparent structures that are coiled anteriorly.

Range and habitat

''Libinia spinosa'' is commonly found at both mud and sand bottoms in the Southwestern

and

oceans. It inhabits Southwestern

waters ranging from

Nova Scotia Nova Scotia is a Provinces and territories of Canada, province of Canada, located on its east coast. It is one of the three Maritime Canada, Maritime provinces and Population of Canada by province and territory, most populous province in Atlan ...

Argentina Argentina, officially the Argentine Republic, is a country in the southern half of South America. It covers an area of , making it the List of South American countries by area, second-largest country in South America after Brazil, the fourt ...

. In the

Ocean, it is found off the coasts of the

United States The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 U.S. state, states and a federal capital district, Washington, D.C. The 48 ...

Baja California Baja California, officially the Free and Sovereign State of Baja California, is a state in Mexico. It is the northwesternmost of the 32 federal entities of Mexico. Before becoming a state in 1952, the area was known as the North Territory of B ...

Galápagos Islands The Galápagos Islands () are an archipelago of volcanic islands in the Eastern Pacific, located around the equator, west of the mainland of South America. They form the Galápagos Province of the Republic of Ecuador, with a population of sli ...

Hawaii Hawaii ( ; ) is an island U.S. state, state of the United States, in the Pacific Ocean about southwest of the U.S. mainland. One of the two Non-contiguous United States, non-contiguous U.S. states (along with Alaska), it is the only sta ...

Peru Peru, officially the Republic of Peru, is a country in western South America. It is bordered in the north by Ecuador and Colombia, in the east by Brazil, in the southeast by Bolivia, in the south by Chile, and in the south and west by the Pac ...

, and

Chile Chile, officially the Republic of Chile, is a country in western South America. It is the southernmost country in the world and the closest to Antarctica, stretching along a narrow strip of land between the Andes, Andes Mountains and the Paci ...

. The depths at which this organism is found at range from the

intertidal zone The intertidal zone or foreshore is the area above water level at low tide and underwater at high tide; in other words, it is the part of the littoral zone within the tidal range. This area can include several types of habitats with various ...

to 170 m. It prefers sediment that contains both

silt Silt is granular material of a size between sand and clay and composed mostly of broken grains of quartz. Silt may occur as a soil (often mixed with sand or clay) or as sediment mixed in suspension (chemistry), suspension with water. Silt usually ...

and

clay Clay is a type of fine-grained natural soil material containing clay minerals (hydrous aluminium phyllosilicates, e.g. kaolinite, ). Most pure clay minerals are white or light-coloured, but natural clays show a variety of colours from impuriti ...

Reproduction

''Libinia spinosa'' engage in precopulatory courting using both olfactory and tactile cues, indirect sperm transfer is common. Females have been shown to exhibit sexual selection with their preference for larger males. The trait that has been shown to be most highly correlated with mate acquisition for males is large

cheliped A chela ()also called a claw, nipper, or pinceris a pincer-shaped organ at the end of certain limbs of some arthropods. The name comes from Ancient Greek , through Neo-Latin '. The plural form is chelae. Legs bearing a chela are called chelipeds ...

size. Males have been shown to exhibit mate guarding where they will maneuver their chelipeds around the female and fight off other males. Precopulatory mate guarding is exhibited significantly longer than postcopulatory mate guarding. Males breed with females by turning the female upside down and below them and subsequently inserting their

gonopod Gonopods are specialized appendages of various arthropods used in reproduction or egg-laying. In males, they facilitate the transfer of sperm from male to female during mating, and thus are a type of intromittent organ. In crustaceans and millipe ...

s into the female's gonophores. Male copulatory organs consist of a long first

and a short stout second

. Females produce 1-3 offspring for each breeding season.

Life cycle

Prezoeal phase

''Libinia Spinosa's'' total length in this phase is 0.8 mm and the

larva A larva (; : larvae ) is a distinct juvenile form many animals undergo before metamorphosis into their next life stage. Animals with indirect development such as insects, some arachnids, amphibians, or cnidarians typically have a larval phase ...

is encased in a

cuticle A cuticle (), or cuticula, is any of a variety of tough but flexible, non-mineral outer coverings of an organism, or parts of an organism, that provide protection. Various types of "cuticle" are non- homologous, differing in their origin, structu ...

. Its rostrum and dorsal spine are folded. The maxillipeds have terminal, retracted

seta In biology, setae (; seta ; ) are any of a number of different bristle- or hair-like structures on living organisms. Animal setae Protostomes Depending partly on their form and function, protostome setae may be called macrotrichia, chaetae, ...

e. This stage lasts 3 to 5 minutes.

Zoeal phase

''Libinia spinosa'' has 2 stages in the zoeal phase of its

l cycle. In the zoeal phase, ''Libinia spinosa'' contains a

with one rostral and one dorsal spine, seven

e are present. The abdominal

somite The somites (outdated term: primitive segments) are a set of bilaterally paired blocks of paraxial mesoderm that form in the embryogenesis, embryonic stage of somitogenesis, along the head-to-tail axis in segmentation (biology), segmented animals. ...

2 of the zoeal phase has 2 dorsolateral projections while the abdominal

3 lacks dorsolateral projections. The abdominal

s 3 and 4 of the zoeal phase have postero-lateral processes. There are 10 marginal

e and 1 apical

e on the scaphognathite.

Megalopa phase

The megalopal phase of ''Libinia spinosa'' contains 1 stage. The rostrum in this phase is deflected ventrally and

s contains spines/tuberance. There are 2 maxillule

endopod The arthropod leg is a form of jointed appendage of arthropods, usually used for walking. Many of the terms used for arthropod leg segments (called podomeres) are of Latin origin, and may be confused with terms for bones: ''coxa'' (meaning hip, : ...

e, 0 maxilla

e, 4 first maxilliped epipod

e, and 6 third maxilliped

Ecology

''Libinia spinosa'' can be classified as a generalist species when it comes to diet. It consumes both mobile and nonmobile prey. It feeds on organisms such as

, poriferans,

cnidaria Cnidaria ( ) is a phylum under kingdom Animalia containing over 11,000 species of aquatic invertebrates found both in fresh water, freshwater and marine environments (predominantly the latter), including jellyfish, hydroid (zoology), hydroids, ...

ns,

mollusks Mollusca is a phylum of protostomic invertebrate animals, whose members are known as molluscs or mollusks (). Around 76,000 extant species of molluscs are recognized, making it the second-largest animal phylum after Arthropoda. The num ...

s, and small

fish A fish (: fish or fishes) is an aquatic animal, aquatic, Anamniotes, anamniotic, gill-bearing vertebrate animal with swimming fish fin, fins and craniate, a hard skull, but lacking limb (anatomy), limbs with digit (anatomy), digits. Fish can ...

.''Libinia spinos''a does not have commercial value but is unintentionally caught in

prawn Prawn is a common name for small aquatic crustaceans with an exoskeleton An exoskeleton () . is a skeleton that is on the exterior of an animal in the form of hardened integument, which both supports the body's shape and protects the intern ...

trawls, an activity which has led to a decline in its population. ''Libinia spinosa'' carries

epibiont An epibiont (from the Ancient Greek meaning "living on top of") is an organism that lives on the surface of another living organism, called the basibiont ("living underneath"). The interaction between the two organisms is called epibiosis. An ep ...

s such as

sea anemone Sea anemones ( ) are a group of predation, predatory marine invertebrates constituting the order (biology), order Actiniaria. Because of their colourful appearance, they are named after the ''Anemone'', a terrestrial flowering plant. Sea anemone ...

s on top of its

Symbiotic relationship with ''Lychnorhiza lucerna''

''Libinia spinosa'' has been shown to engage in a

symbiotic Symbiosis (Ancient Greek : living with, companionship < : together; and ''bíōsis'': living) is any type of a close and long-term biolo ...

relationship with the medusa ''

'', mainly during its juvenile stages. ''Libinia spinosa'' burrows itself in the subgenital pockets of ''

''.''Libinia spinosa'' is protected from predators by the stinging

cnidocyte A cnidocyte (also known as a cnidoblast) is a type of cell containing a large secretory organelle called a ''cnidocyst'', that can deliver a sting to other organisms as a way to capture prey and defend against predators. A cnidocyte explosively ...

s of ''

'' and also ingests food particles collected by ''

''. Additionally, this relationship allows ''Libinia spinosa'' to move through the environment while conserving its own energy. There is no clear benefit to ''

'' hosting ''Libinia spinosa'' so their

symbiotic Symbiosis (Ancient Greek : living with, companionship < : together; and ''bíōsis'': living) is any type of a close and long-term biolo ...

relationship is likely a form of

commensalism Commensalism is a long-term biological interaction (symbiosis) in which members of one species gain benefits while those of the other species neither benefit nor are harmed. This is in contrast with mutualism, in which both organisms benefit fr ...

References

{{wikispecies Majoidea Crustaceans of Brazil Crustaceans described in 1834