Common name: collector urchin

General information

The Collector Urchin, scientifically known as Tripneustes gratilla, is a tropical sea urchin that is popular among reef aquarium hobbyists. This species is known for its distinctive test (shell) covered with variable colored spines that can range from white to green or purple. It is often found in shallow waters and is known for its role in controlling algae within the reef ecosystem.

Care

Collector Urchins require an established aquarium with plenty of live rock and algae for grazing. They are excellent algae eaters and can help keep the tank clean. However, they may topple corals or move small rocks as they forage, so it's important to secure corals well. They are sensitive to high nitrate levels and require stable water conditions.

Reproduction

In the wild, Tripneustes gratilla reproduces by releasing gametes into the water column in a process known as broadcast spawning. In the aquarium, breeding is less common but can occur if conditions are ideal. The larvae are planktonic before settling and metamorphosing into juvenile urchins.

Symbiosis

Collector Urchins sometimes have a symbiotic relationship with small fish or shrimps that seek refuge among their spines. This relationship provides protection for the smaller creatures while the urchin benefits from the cleaning and removal of parasites by its symbionts.

Habitat

This species is commonly found in the Indo-Pacific region, from the Red Sea and East Africa to the tropical waters of the western Pacific. They inhabit a variety of environments including seagrass beds, coral reefs, and rocky substrates, typically in shallow waters.