Long-spined Sea Urchin

Although its test is only 7–9 cm, the long-spined sea urchin covers an area of 25–30 cm with its thin, black and very long spines. The orange ring and five small white dots on top of its body make it easy to identify. Its spines are hollow, brittle and mildly venomous; they easily pierce the skin, break off and stay inside, and remain painful for a long time. It has been seen as an invasive species along Türkiye's Mediterranean coast since the 2000s; individuals from the aquarium must never be released into the sea.

• 300 liters or more; large caves to hide in during the day and enough open space.
• Salinity specific gravity 1.024–1.026, pH 8.1–8.4, temperature 24–27°C; salinity should be stable.
• Reef safe with caution: it does not attack corals, but it grazes coralline algae and can knock over loose pieces with its spines.
• Wear gloves when putting your hands in the aquarium; when moving it, catch it with a water-filled container rather than bare hands.
• It should be acclimated by the drip method for at least 2 hours; copper-based medications are lethal.

Herbivorous; it eats algae film, filamentous algae and coralline algae. When algae run low, nori or seaweed sheets should be offered.

Active at night; during the day it waits in caves with its spines spread outward. When a shadow falls on it, it quickly turns its spines in that direction.

Good companions: tangs, cardinalfish, clownfish; large shrimp and snails.

Avoid: triggerfish, pufferfish and large wrasses; small, cramped aquariums that require frequent reaching in.