Green Sea Urchin

Geographical Origin and Habitat: Western Atlantic Ocean, from North Carolina to Brazil, including the Caribbean Sea. Found in shallow seagrass beds and sandy reef flats.

Taxonomy: Family Toxopneustidae, genus Lytechinus. Rounded body covered in short spines. Reaches a diameter of about 11 cm.

Social Behavior: Peaceful herbivore. Exhibits 'covering behavior,' using its tube feet to carry shells and stones on its back for UV protection.

Coloration and Sexual Dimorphism: Body ranges from light green to white or light purple, with matching short spines. No distinct visual differences between sexes.

Tank Setup: An aquarium of at least 100 liters with firmly secured rockwork is required. High levels of natural algae growth will sustain it.

Diet and Feeding: Primarily herbivorous. Consumes large quantities of nuisance hair algae and film algae. Supplement with dried nori sheets if algae runs low.

Water Quality: Stable reef parameters. Keep temperature at 22-27 °C, pH at 8.1-8.4, and specific gravity at 1.023-1.025. Monitor calcium levels (400-450 ppm).

Compatibility and Tankmates: Great for reef tanks. However, unsecured corals may be bulldozed and knocked over as the urchin moves.

Aquarium Breeding: Captive breeding is not documented. Spawns sexually by releasing gametes directly into the water column.

Risks and Diseases: Highly sensitive to copper. Spine loss is a key indicator of poor water quality, starvation, or osmotic shock.