Long-spined Sea Urchin
Diadema antillarumAlso known as Lime Urchin, Black Sea Urchin
Long-spined sea urchins act as vital lawnmowers of the Caribbean, grazing night and day on turf algae that would otherwise smother fragile coral reefs. Their exceptionally long, needle-sharp spines pivot in all directions to deter predators while providing a safe nursery habitat for tiny juvenile fish. During the day, they squeeze into dark reef crevices, emerging at sunset to forage across the seafloor.
- diet
- Herbivore (primarily turf algae and seagrass)
- family
- Diadematidae
- threats
- Water pollution, climate change, and epidemic diseases
- life Span
- 4 to 6 years
NE
Long, brittle spines easily puncture skin and inject mild venom; avoid touching or stepping on them.
The long, hollow spines easily pierce wetsuits and skin, breaking off inside the wound and releasing a mild toxin that causes burning pain and swelling.
Never attempt to touch or handle this animal, and maintain careful buoyancy control when swimming near reef structures.Mass mortality events caused by waterborne pathogens have devastated populations, triggering severe algal overgrowth on coral reefs.
Avoid disturbing surviving individuals and report any sightings of sick or bald urchins to local marine conservationists.- Observe from a distance: Maintain neutral buoyancy to avoid drifting into reef crevices where they hide.
- Watch for spine movement: Notice how the spines actively pivot toward shadows or nearby movement as a defensive reflex.
- Look for companions: Search the spine canopy for tiny, commensal shrimp or juvenile fish seeking shelter.