|Terrestrial adaptations in the Anomura (Crustacea: Decapoda)|
Greenaway, P. (2003). Terrestrial adaptations in the Anomura (Crustacea: Decapoda). Mem. Mus. Vic. 60(1): 13-26
In: Memoirs of the Museum of Victoria. Museum of Victoria: Melbourne. ISSN 0814-1827, more
In this review, morphological, physiological and behavioural adaptations to life on land by anomurans are considered. The most terrestrial group are the Coenobitidae and these have developed terrestrial adaptations broadly similar to those of the terrestrial brachyurans. The coenobitids have developed two evolutionary, terrestrial lines. Coenobita spp. retain the protective gastropod shell and this has placed a set of constraints on morphological, physiological and behavioural development particularly in regard to gas exchange, osmoregulation and excretion. Birgus do not carry molluscan shells after the juvenile stages and, freed from its constraints, reach larger size and have developed terrestrial adaptations that closely parallel those of the brachyuran land crabs. Shell retention by Coenobita has resulted in development of novel abdominal gas exchange organs whilst purine excretion by B. latro seems to be unique amongst land crabs. Crabs of both genera are well adapted to life on land in terms of sensory, respiratory, excretory and osmoregulatory functions and they can also moult, mate and lay eggs effectively on land. Several species have the functional ability to live in a range of habitats from rainforest to arid scrubland but their penetration of these habitats is limited to small islands or to a narrow coastal strip. This is probably due to the retention of pelagic larval stages and to the lack of molluscan shells of suitable dimensions and strength in inland situations, which restrict the range to a manageable distance from the sea.