Diadema antillarum Breeding Guide: Caribbean Urchin & Restoration
The Caribbean long-spine urchin is a prolific broadcast spawner, key to reef health after its 1983 die-off. Not home-bred, but cultured for reef restoration.
Overview
Diadema antillarum, the Caribbean long-spined sea urchin, belongs to the family Diadematidae. It inhabits the tropical Western Atlantic, including the Caribbean Sea, Gulf of Mexico and South American coasts to Brazil, with populations in the East Atlantic and Indian Ocean. Spines are typically 10-12 cm and can reach 30 cm in large individuals. It is the primary herbivore on Caribbean reefs, grazing algae that would otherwise smother corals.
Reproductive Mode
The species is a highly fecund broadcast spawner, with individuals producing over a million eggs per spawning event. Spawning relies on chemical signalling between males and females to synchronise gamete release.
Sexual Reproduction
Gametes are released into the water for external fertilisation, and the embryos develop into planktonic larvae that drift before settling on the reef and metamorphosing into juveniles. Dedicated nurseries in Jamaica and Puerto Rico now culture juveniles for relocation, with promising reef-recovery results in some regions, but this is aquaculture for restoration rather than home breeding.
Common Challenges
More than 97% of urchins died in the 1983 Caribbean mass die-off from an unknown disease, causing macroalgal overgrowth that inhibited coral recovery and reduced reef resilience; populations are recovering slowly. The planktonic larval cycle cannot be completed in home aquaria, and urchins do not reproduce asexually.