Collector Urchin

About

The pincushion urchin (Tripneustes gratilla) is one of those invertebrates that earns its keep in a saltwater tank almost immediately. Found across the Indo-Pacific on shallow reef flats and seagrass beds, it spends its days methodically grazing on algae, making it a genuinely useful addition to any cleanup crew. What sets it apart from other urchins is its habit of decorating itself with bits of rubble, shell, and debris, which it holds in place with its tube feet. In the wild this behavior may offer camouflage or UV protection, but in the aquarium it just looks charming and a little eccentric. The spines are shorter and less sharp than those of some other urchins, which makes accidental encounters with your hand a little less dramatic. It is considered a solid choice for beginners, provided the tank has established algae growth to keep it fed and enough rock and open substrate to roam. Like all echinoderms, it is sensitive to sudden shifts in salinity and will not tolerate copper-based medications, so acclimate it carefully and keep tank chemistry stable. This is a low-drama, high-function resident that suits a wide range of reef setups.