Identification: an oval body 10 to 20 cm long, in variable colours (often red, violet, blue, yellow), with rows of tube feet; a crown of branched, feathery tentacles rings the mouth. The genus Pseudocolochirus has at least two species in the trade, and sources disagree on their names: LiveAquaria sells P. violaceus as the 'Philippine' sea apple (yellow feet, blue-violet oral region) and P. axiologus as the 'Australian' sea apple (blue body, red feet), while Rob Toonen has it the other way round. Check with your supplier.
In the wild it is an obligate filter feeder of the Indo-Pacific: anchored by its tube feet in a well-flushed spot, it spreads its tentacles, mostly at night, to catch plankton, then brings them to its mouth one by one. When stressed it can shrink to a minimum or, on the contrary, swell with water to double its size and drift on the current: a fully inflated animal in a shop is often stressed, not healthy.
Defence and reproduction: when disturbed it can expel its viscera and release a toxic saponin, holothurin, into the water; its death can also release a lot of ammonia. As in other sea cucumbers, the sexes are separate and fertilisation is external; none of the sources consulted documents breeding in aquaria. Few aquarists have kept one alive for more than three years.
Status: the species has not been evaluated by the IUCN. It is not CITES-listed.
