''Xantho poressa'', the jaguar round crab, is a

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

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 ...

from the eastern

Atlantic Ocean The Atlantic Ocean is the second largest of the world's five borders of the oceans, oceanic divisions, with an area of about . It covers approximately 17% of Earth#Surface, Earth's surface and about 24% of its water surface area. During the ...

. It is one of four species in the genus ''

Xantho ''Xantho'' is a genus of crabs in the family Xanthidae, containing five extant species, all restricted to the north-east Atlantic Ocean and Mediterranean Sea, although ''Xantho granulicarpis'' is not universally recognised as a separate species f ...

''.

Description

The juveniles of ''X. poressa'' are cryptically coloured as camouflage among the

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 on the leaves of ''Posidonia'' with a variable carapace colour, which can be yellowish, reddish, brown, or dark grey with patches of another colour, usually white. The pereiopods are usually banded with dark brown or black bands alternating with white or translucent stripes or spots, although the fifth pereiopod is brighter and often unmarked. The adults are uniformly dark grey in colour and they leave the seagrass beds for more open, rocky substrates.

Distribution

''X. poressa'' is distributed throughout the

Black Sea The Black Sea is a marginal sea, marginal Mediterranean sea (oceanography), mediterranean sea lying between Europe and Asia, east of the Balkans, south of the East European Plain, west of the Caucasus, and north of Anatolia. It is bound ...

and the

Mediterranean Sea The Mediterranean Sea ( ) is a sea connected to the Atlantic Ocean, surrounded by the Mediterranean basin and almost completely enclosed by land: on the east by the Levant in West Asia, on the north by Anatolia in West Asia and Southern Eur ...

and into the warmer parts of the north eastern Atlantic to 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 ...

Biology

The larvae of ''X. poressa'' go through four

zoea Crustaceans may pass through a number of larval and immature stages between hatching from their eggs and reaching their adult form. Each of the stages is separated by a moult, in which the hard exoskeleton is shed to allow the animal to grow. The ...

l and one

megalopa Crustaceans may pass through a number of larval and immature stages between hatching from their eggs and reaching their adult form. Each of the stages is separated by a moult, in which the hard exoskeleton is shed to allow the animal to grow. The ...

l stages, which are typical of most of the related species of crabs in the subfamily Xanthinae. The duration of each zoeal stage is 2–4 days and the megalopa stage lasts an average of 10 days, with the first juvenile crab stage being reached after 23 days. Juveniles live in ''

Posidonia ''Posidonia'' is a genus of flowering plants. It contains nine species of marine plants ("seagrass"), found in the seas of the Mediterranean and around the south coast of Australia. The APG system (1998) and APG II system (2003) accept this ge ...

'' meadows until their last

moult In biology, moulting (British English), or molting (American English), also known as sloughing, shedding, or in many invertebrates, ecdysis, is a process by which an animal casts off parts of its body to serve some beneficial purpose, either at ...

, when they migrate to the nearest rocky

substrate Substrate may refer to: Physical layers *Substrate (biology), the natural environment in which an organism lives, or the surface or medium on which an organism grows or is attached ** Substrate (aquatic environment), the earthy material that exi ...

. In the Black Sea, ''X. poressa'' is common near the shoreline at depths less than 1 m; it is mainly found stones on substrates of pebble and crushed rock; it is rare on the other substrates and may occur down to 15 m in depth. Xantho poressa 2009 G1

References

External links

* * {{Portal bar, Crustaceans Xanthidae Crabs of the Atlantic Ocean Fauna of the Mediterranean Sea Fauna of the Black Sea Crustaceans described in 1792 Taxa named by Giuseppe Olivi