From ReefPedia

[edit] Black Longspine Urchin Scientific Name Echinoidea Diadema Max. Size: Up to seven inches including spines (3" carapace+spines). Commonly seen approx. three inches with spines Tank Size: Min 30 gallons Aggression: Moderate, may eat path through coral polyps Poisonous: Yes Hardiness: Very sensitive to nitrate and alkaline levels Reef-Safe: Modified yes Available as captive-bred: Unknown Hitchhiker? No

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Physical Description

Small urchin body with unusually long spines that on close inspection are individually and symetrically banded dark gray and brown/black. Overall impression is black. Small white nodule with red highlight at top of shell ends the digestive tract. Five small white highlighs may be seen syetrically around perimeter of carapace.

Distribution

Collected in Indonesia

Taxonomic Stuff you know you Care About

Keep water quality high (SG 1.023 - 1.025, pH 8.1 - 8.4, Temp. 72 - 78° F) Spines are mildly venomous and may be painful. Also emits poisons upon death

Loss of spines indicate an excessive nitrate level in the tank. (Anecdotaly this has been seen with nitrate levels higher than 20 ppm.)

• Genus: Diadema

• Species: savignyi

Behavior

The longspine urchin uses its lower spines to locomote on live rock, substrate and glass surfaces of the tank. It is generally nocturnal. It likes to eat green filamentous algae and corraline algae

Feeding

Omnivore, self-feeding. This animal also benefits from supplemental feedings (pieces of squid, fish, or scallop)

Breeding

Can be made to release gamites with mild electrical stimulation.

Social Structure

Solitary, generally unperturbed by tankmates.

Additional Notes

An aggressive algae eater. A die-off of black longspine urchins on the western Atlantic Ocean several years ago seems to have resulted in an exponential increase of algae which in turn severely damaged coral structures from Florida to South America.

WARNING: The longspine urchin is poisonous! Care should be taken when handling.