Collector Urchin

Overview

The Collector Urchin (Tripneustes gratilla) is a widespread sea urchin species found throughout tropical and subtropical waters of the Indo-Pacific. It plays a vital role in coral reef ecosystems by grazing on algae and seagrass, which helps maintain the balance of benthic communities.

Appearance

This species is characterized by a round body covered in relatively short, dense spines. It is well-known for its "covering" behavior, where it uses its tube feet to attach various materials—such as shell fragments, pebbles, and bits of algae—to its dorsal surface. This habit serves as protection against predators, intense sunlight, and strong water currents.

Biology & behavior

Collector Urchins are primarily active grazers that feed both day and night. While they are often found in groups, they are not strictly social and may also be encountered individually. They move slowly across the substrate, typically covering about a meter per day. As members of the family Toxopneustidae, they possess spines that can be toxic, providing an additional layer of defense against predators like pufferfish and octopuses.

Feeding

As an omnivorous grazer, this urchin consumes a wide variety of macroalgae, periphyton, and seagrasses. Its feeding activity is ecologically significant, as it can effectively control algal overgrowth on reefs. When presented with a diverse selection of food, these urchins often show specific preferences, though they are highly adaptable and will readily consume whatever algal resources are most available in their immediate environment.