Synapta maculata

Not recommended: Meerwasser-Lexikon rates it unsuitable for aquarium keeping. It is rarely kept because of its size, its sticky ossicles and its fragile body, which easily gets trapped in water circulation systems.

Handling: its skin can tear if it is lifted out of the water, and its ossicles hook in so firmly that the animal sometimes has to be torn to get free. Never lift it out of the water; move it in a submerged container, wearing gloves. Acclimation: sea cucumbers are sensitive to changes in salinity. Acclimate it slowly by drip in a separate container, then move it without pouring the shipping water into the tank. Handle it as little as possible and with gloves: handling or relocating it can by itself trigger the release of holothurin.

Its tiny anchor-shaped ossicles snag on everything they touch: when the animal suddenly retracts, they can tear or injure the tissue of a coral it was lying on and dislodge loosely fixed frags. Toxicity: synaptids have neither a respiratory tree nor Cuvierian tubules and are said to be relatively non-toxic, but their skin holds distasteful compounds and they are reported to be highly toxic to fish when seriously injured, for example shredded in a pump or against an overflow grate.

Fit every pump, powerhead and overflow intake with a large, securely fixed strainer: according to Rob Toonen, most 'cuke nukes' happen when a sea cucumber is sucked in and shredded. If it happens anyway, remove the animal at once, make a large water change, increase skimming and add activated carbon.

Like other invertebrates, it tolerates neither copper treatments nor high nitrate; never put it in a copper-treated tank, not even in quarantine.

It feeds on organic matter and biofilm that it collects from surfaces with its sticky tentacles, on sand, rubble and seagrass blades. Synaptids are the most active sea cucumbers and need a lot of food: their tentacles constantly dab the substrate, ingested particles pass through in about an hour, and they only really feed at night. A synaptid active in broad daylight in an aquarium is not necessarily eating, and may be starving.