Green Rock Urchin

Geographical Origin and Habitat: Native to the Caribbean Sea, the Bahamas, and Florida. Inhabits shallow coral reefs, often boring into soft limestone rock for protection.

Taxonomy: Belongs to the Echinometridae family. Features a globose test covered with thin, sharp spines of greenish to olive coloration.

Social Behavior: Solitary and nocturnal. Stays wedged in rocky crevices during daylight hours to avoid predators and emerges at night to forage.

Coloration and Sexual Dimorphism: Spines are green or reddish-green, often with lighter rings near the base. No visible external dimorphism between males and females.

Tank Setup: Needs a mature tank of 50-70 gallons or more. Live rocks must be securely stacked, as their heavy grazing and movement can dislodge unstable structures.

Diet and Feeding: Herbivore. Primarily grazes on film algae, hair algae, and macroalgae. Supplement with dried seaweed (nori) if natural algae levels are low.

Water Quality: Requires clean, stable marine parameters: temperature 24-27°C, pH 8.1-8.4, SG 1.023-1.026. Keep nitrates below 10 ppm.

Compatibility and Tankmates: Safe with most fish and large invertebrates. Use caution with small corals or frags, as the urchin may knock them over or graze on them.

Aquarium Breeding: Broadcast spawners releasing gametes directly into the water column. Raising the planktonic larvae in home aquaria is currently not achieved.

Risks and Diseases: Highly sensitive to copper treatments and sudden salinity drops. Dropping spines is a major warning sign of stress or poor water parameters.