FAO Species Identification Guide for Fishery Purposes Western

1154 Crabs
Infraorder Anomura - Coenobitidae Infraorder ANOMURA
COENOBITIDAE
Land hermit crabs and coconut crabs
Diagnostic characters: Carapace relatively well calcified; eyestalk laterally flattened; eyes usually
held subparallel to each other. Antennae laterally flattened. Coxae of third maxillipeds close
to each other, without distinct gap between them. Chelipeds short, stocky, equal or unequal; when
unequal, left chela larger. First 2 pairs walking legs, last 2 pairs reduced, chelate. Abdomen bilaterally
asymmetrical, not clearly divided into segments. Either hermit crabs or distinctly crab-like animals with
abdomen tucked under carapace; uropods modified into a “rasp” used for clinging interior of
gastropod shells (except in adult Birgus latro).
antenna
laterally
flattened
eye
laterally
flattened
last leg strongly
reduced
carapace
pyriform
3 rd leg with
chela
Habitat, biology, and fisheries: All members of the Coenobitidae are fully terrestrial, but they must return
to the sea to release their larvae. Most species live in gastropod shells. None of the species, other than
the “coconut crab” Birgus latro, have any fishery value, although many species of land hermit crabs (genus
Coenobita) are regularly collected for the pet trade.
Similar families occurring in the area
Only the hermit crabs of the families Diogenidae and Paguridae may be confused with coenobitids, but
their habitats are exclusively aquatic, not terrestrial. In addition, the laterally flattened antennae are highly
diagnostic for the Coenobitidae.
References
Brown, I. W. and D. R. Fielder (eds). 1991. The coconut crab: aspects of Birgus latro biology and ecology in Vanuatu.
Canberra, Australian Centre for International Agricultural Research (ACIAR), Monograph Number 8:i-x, 128 p.
Miyake, S. 1965. The Crustacea Anomura of Sagami Bay. Tokyo, Biological Laboratory of the Imperial Household, 161 p.