''Percnon gibbesi'' is a species of

crab Crabs are decapod crustaceans of the infraorder Brachyura, which typically have a very short projecting "tail" (abdomen) ( el, βραχύς , translit=brachys = short, / = tail), usually hidden entirely under the thorax. They live in all the ...

. It is one of at least two species commonly called "Sally Lightfoot" (the other being the semi-terrestrial '' Grapsus grapsus'' from the Pacific coast of the Americas), and is also referred to as the ''nimble spray crab'' or ''urchin crab''. It has been described as "the most invasive decapod species to enter the Mediterranean".

Description

Adults have a

carapace A carapace is a Dorsum (biology), 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 tor ...

wide, and

legs A leg is a weight-bearing and locomotive anatomical structure, usually having a columnar shape. During locomotion, legs function as "extensible struts". The combination of movements at all joints can be modeled as a single, linear element ...

with yellow rings at the joints. Each of the five pairs of walking legs has a row of spines along the leading edge. Females carrying eggs have been caught off West Africa between February and April and August; the larvae which hatch from them are planktonic and long-lived, which may contribute to the species'

invasiveness Minimally invasive procedures (also known as minimally invasive surgeries) encompass surgical techniques that limit the size of incisions needed, thereby reducing wound healing time, associated pain, and risk of infection. Surgery by definition ...

Taxonomy

The genus ''

Percnon ''Percnon'' is a genus of crabs. It is "doubtfully placed" in the family Plagusiidae, and it has also been included in the family Grapsidae. Species Seven species are recognised: *''Percnon abbreviatum'' (Dana, 1851) *''Percnon affine'' (Henri ...

'' is currently "doubtfully placed" in the family Plagusiidae, and it has also been included in the family

Grapsidae The Grapsidae are a family of crabs known variously as marsh crabs, shore crabs, or talon crabs. The family has not been confirmed to form a monophyletic group and some taxa may belong in other families. They are found along the shore among rocks ...

Distribution

''P. gibbesi'' is one of the most widespread grapsid crabs, being found on both sides of the Atlantic Ocean and on the Pacific coast of

North America North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and the Car ...

. There, its range extends from California to Chile, while in the Atlantic, it occurs natively from Florida to Brazil and from

Madeira ) , anthem = ( en, "Anthem of the Autonomous Region of Madeira") , song_type = Regional anthem , image_map=EU-Portugal_with_Madeira_circled.svg , map_alt=Location of Madeira , map_caption=Location of Madeira , subdivision_type=Sovereign st ...

to the Gulf of Guinea. It has recently invaded the Mediterranean Sea, having first been discovered at Linosa, Sicily in 1999. It has subsequently been found on the

Balearic Islands The Balearic Islands ( es, Islas Baleares ; or ca, Illes Balears ) are an archipelago in the Balearic Sea, near the eastern coast of the Iberian Peninsula. The archipelago is an autonomous community and a province of Spain; its capital is ...

, in Greece, in Libya in Malta and in Israel.

Ecology

Unusually among temperate crabs, ''P. gibbesi'' is strictly herbivorous. In the Caribbean Sea, ''P. gibbesi'' is associated with the

sea urchin Sea urchins () are spiny, globular echinoderms in the class Echinoidea. About 950 species of sea urchin live on the seabed of every ocean and inhabit every depth zone from the intertidal seashore down to . The spherical, hard shells (tests) of ...

'' Diadema antillarum''. In the Mediterranean Sea, ''P. gibbesi'' lives almost exclusively among boulders, and is out-competed by the native species '' Pachygrapsus marmoratus''. ''P. gibbesi'' is preyed upon by fish and invertebrates.

References

External links

* * {{Taxonbar, from=Q1439666 Grapsoidea Crustaceans of the Atlantic Ocean Crustaceans of the eastern Pacific Ocean Crustaceans described in 1853 Taxa named by Henri Milne-Edwards