Collector Urchin

The collector urchin gets its name from the way it gathers pieces of shell, stone and algae on top of itself with its tube feet. Its test reaches 10–12 cm; its dark purple body is densely covered with short spines in white and orange tones. It is one of the most effective animals for fighting stubborn filamentous algae, but its appetite and size make it unsuitable for small aquariums. Echinoderms are very sensitive to changes in salinity. Those on the market are wild-collected.

• A mature aquarium of 200 liters or more; live rock with plenty of algae.
• Salinity specific gravity 1.024–1.026, pH 8.1–8.4, temperature 24–27°C; salinity should be stable.
• Reef safe with caution: it does not attack corals, but it knocks over unsecured frags or picks them up onto itself, and it grazes coralline algae.
• In aquariums with a macroalgae compartment (Chaetomorpha, Caulerpa) it also eats these algae.
• It should be acclimated by the drip method for at least 2 hours; copper-based medications are lethal.

Herbivorous; it eats filamentous algae, algae film, coralline algae and macroalgae. When algae run low, nori or seaweed sheets should be offered secured to a stone; when it goes hungry it sheds its spines.

Peaceful; it grazes day and night as it moves slowly around. Advancing over the rocks like a bulldozer, it can dislodge loose pieces.

Good companions: tangs, clownfish, cardinalfish; shrimp, snails.

Avoid: triggerfish, pufferfish, large wrasses; compartments where macroalgae are grown and unsecured coral frags.