Summary
Physical Description
Ecology
Life History & Behaviour
Anatomy & Physiology
Evolution & Systematics
Biogeographic Distribution
Conservation & Threats
References & Links | Anatomy & Physiology
Digestive System
The gut of a hermit crab consists of the foregut, migut and hindgut. Food is passed down the oesophagus and into the stomach where it is ground down into fine particles (Poore & Museum 2007). The particles move through to the midgut where absorption of the nutrients occur, once all the nutrients have been absorbed the remains move through to the hindgut where they are passed out through the anus, which is located near the telson (Poore & Museum 2007).
Respiration
Hermit crabs respire through gills that are located and protected under the carapace, these gills branch of into two chambers; the inhalant and exhalant chamber (O'mahoney & Full 1984). Respiration happens via water entering into the inhalant chamber and exiting through the exhalant chamber. Gas exchange occurs in the inhalant chamber (O'mahoney & Full 1984).
Exoskeleton
The exoskeleton of crustaceans is made up of a mineralised fibrous chitin-based tissue (Raabe et al. 2005). Hermit crabs, however lack this exoskeleton on their abdomen, instead they are protected by their shell. The exoskeleton is made up of three layers of calcified cuticle; the epicuticle, exocuticle and endocuticle (Roer & Dillaman 1984). Hermit crabs moult their exoskeleton periodically in order to grow (Roer & Dillaman 1984). Moulting is a sensitive time for hermit crabs as this is when they are most vulnerable to environmental factors and predation. |
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