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Fact Sheet





Life History & Behaviour

Life Cycle



Anatomy & Physiology

Dromiidae vs. Carpiliidae



Biogeographic Distribution

Conservation & Threat

References & Links

Having a biphasic life style, means that various behaviours are vastly different at different life stages of the sponge crab.


Zoea Stage -  mainly feed on planktonic organisms, preys are captured by lashing the abdomen back and forth, they then direct the preys to the mandibles for ingestion (Williamson, 1982).

Megalopa Stage -  capture and manipulate preys with chelae, and then direct preys to mouth for ingestion (Williamson, 1982).

Adult Stage -  Predominantly herbivorous, they feed mainly on algae by scraping algae from hard substrates by alternate movement of their two spoon-tipped chelipeds, and deliver food (a combination of algae, detritus and rocky fragments) into mouth (Warner, 1977).


Females become receptive to mating after moulting, and their shells become soft.  

Courtship is induced by pheromone which is released by the females in urine (Ingle, 1997).  During copulation, male embraces the female with chelipeds and pereiopods, and holds her in position.  The ventral surface of the crabs are opposed.  The male inserts its pleopods into the female's genital opening as the abdomens of both crabs enfold.  

The duration of copulation can last from a minute to close to 6 minutes ( Warner, 1977).


Zoea Stage - swimming by anteriorly directed beating of maxillipeds, head is held downwards with dorsal spine foremost and abdomen trailing.  Direction of swimming and dispersal of larvae are directly influenced by light, gravity and water circulation at different depths (Williamson, 1982).

Megalopa Stage -  swimming by pleopods borne on the extended abdomen, body is streamlined by tucking in the first two pairs of walking legs (Williamson, 1982).

Adult Stage -  sideway walking with first two pairs of pereiopeds (Warner, 1977).


Perhaps this is one of the most important biological processes of the crustaceans.  It enables them to grow larger in size and it is controlled by the endocrine system of the crustaceans ( the release of the steroid hormone: ecdysone).

Moulting is an energetically expensive process, the crab's normal behaviour is temporarily suspended for a short period of time just before and after moulting.  There are four basic stages of moulting: Intermoult, Proecdysis, Ecdysis and Postecdysis  (Warner, 1977).

The following diagram shows the series of moulting in Arthopoda.

Adapted from Ruppert et al, 2004.

After moulting, the crab is left with a soft exoskeleton.  As mentioned above in the Reproduction section, moulting also contributes to the reproductive cycle of the crabs.  The sponge or ascidian cap is also replaced after each moult.