Coenobita compressus(EN)

Image©Pablo Cervantes

Common name

Ecuadorian land hermit crab, E-Crab, E, Pacific hermit crab.

Size

Carapace length can reach 18mm.

Distribution

Zone of the Lower California to Chile, e.g. Mexico, Costa Rica, Panama, Colombia, Ecuador, Peru etc. Only species known from American West Coast and restricted to this coast. Records from the Indo West Pacific are misidentifications. Also present in the Galapagos Islands.

Habitat

Most found in area which are devoid of dense undergrowth. They can also be found under ledges, in small rocky caves, under driftwood or dug into the sand. In humid vegetated areas, they remain active during the day. Live close to the shore, and enter either the sea or brackish water regularly to replenish the water in their shells. They seem to need regular access to water of high salinity.

Larval stages

Four to Five zoeal stages.

Characteristics

Adult
Body colour is vary form pale grey to brown, light brown, tan, orange-brown and dark grey and the colouration may be uniform or show considerable variation. There are light and dark brown granules on the whole body.

Black diagonal (/) stripe behind the bases of antenna, on lateral borders of shield. Not obvious on individuals with dark body colour.

Eyestalks
Eyestalks are compressed in shape. The eyes like a ‘，’(comma).

The eyes of some individuals are brown.

Antenna
Flagellum of antennule (1st antennal) and antenna are dark brown.

Cheliped
Left cheliped is bigger than right cheliped. There is series of 4-5 ridges (////) on upper outer surface of palm of left cheliped.

Upper margins of both cheliped with brush of setae.

Both cheliped with light and dark brown granules.

Walking legs
Colour of dactylus of left 2nd walking legs is always darker than other parts of the legs.

Both 2nd and 3rd walking legs with light and dark brown granules.

Colour of Dactylus, propodus of left 3rd walking leg is different with carpus of same leg.

Abdomen
The abdomen is short.

Male coxae of 5th legs
Below image is from the specimen I collected.

Juvenile
Body colour range from blue-green to gray-brown and their colouration is generally uniform.

Remark

1. Coenobita compressus will modify the inside of marine shells to increase internal volume.

2. Coenobita compressus use six-legged locomotion. They use their chelipeds as support levers, while the two pair of walking legs are used for thrust. They move forward using a tripod gait similar to that observed in insects.

3. Coenobita compressus has usually been misidentified as Coenobita rugosus.

Gallery

Reference links

coenobita.e-monsite.com
coenobitaspecies.com

Reference articles

Ball E. E., 1972. Observations on the biology of the hermit crab, Coenobita compressus H. Milne Edwards (Decapoda; Anomura) on the west coast of the Americas
Boone L., 1931. ANOMURAN, MACRURAN CRUSTACEA FROM PANAMA AND CANAL ZONE
Brodie R., Harvey A. W., 2001. Larval Development of the Land Hermit Crab Coenobita compressus H. Milne Edwards Reared in the Laboratory
Brodie R. J., 1999. Ontogeny of shell-related behaviors and transition to land in the terrestrial hermit crab Coenobita compressus H. Milne Edwards
Bright D. B., 1966. The Land Crabs of Costa Rica
Burggren W. W., McMahon B. R., 2009. Biology of the Land Crabs, Cambridge University Press
Contreras-Garduno J., Osorno J. L., Cordoba-Aguilar A., 2007. Male-Male Competition and Female Behavior as Determinants of Male Mating Success in the Semi-Terrestrial Hermit Crab Coenobita Compressus (H. Milne Edwards)
Contreras-Garduno J., Osorno J. L., Macias-Garcia C., 2005. Long-term costs of using heaving shells in terrestrial hermit crabs (Coenobita compressus) and the limits of shell preference
Contreras-Garduno J., Osorno J. L., Macias-Garcia C., 2009. Weight difference threshold during shell selection relates to growth rate in the semi-terrestrial hermit crab Coenobita compressus
Herreid C. F., Full R. J., 1985. Locomotion of Hermit crabs (Coenobita compressus) on Beach and Treadmill
Hung-Li Yuan, 2008. Morphological and Molecular Evidence for a Stepwise Terrestrial Evolution and Species Delimitation on the Coenobita Phylogeny
Kurta A., 1982. Social facilitation of foraging behavior by the hermit crab, Coenobita compressus, in Costa Rica
McLaughlin P. A., Komai T., Lemaitre R., Rahayu D. L., 2010. Annotated checklist of anomuran decapod crustaceans of the world (exclusive of the Kiwaoidea and families Chirostylidae and Galatheidae of the Galatheoidea) Part I. Lithodoidea, Lomisoidea and Paguroidea
Thacker R. W., 1996. Food choices of land hermit crabs (Coenobita compressus H. Milne Edwards) depend on past experience
Thacker R. W., 1998. Avoidance of recently eaten foods by land hermit crabs, Coenobita compressus
仲宗根幸男, 2015. 沖縄の天然記念物シリーズ講演12　オカヤドカリたち

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