Long Spine Sea Urchin Care Guide
Diadema setosum is an Indo-Pacific urchin with very long, mildly venomous black spines. It is an effective algae grazer for large reef tanks.
Overview
Diadema setosum, the long-spine sea urchin, is an echinoid of the family Diadematidae from the Indo-Pacific. Its spines are extremely long and narrow in proportion to the body, hollow, and carry a mild venom; the test is black and marked by five white spots, with a bright orange ring around the periproctal cone. It is a prolific algae grazer and a useful, if hazardous, cleanup animal in large reef systems.
Taxonomy
- Class: Echinoidea
- Order: Diadematoida
- Family: Diadematidae
- Genus: Diadema
- Scientific name: Diadema setosum (Leske, 1778)
Habitat
The species ranges throughout the Indo-Pacific basin, from the Red Sea eastward to Australia, north to Japan and south to the east coast of Africa. It occupies coral reefs, sand flats and seagrass beds, where it can reach high local densities. Adults measure about 70 mm in test diameter and 40 mm in height.
Tank requirements
- Minimum tank volume: 200 L
- Temperature: 24–26 °C (75–79 °F)
- pH: 8.1–8.4
- Carbonate hardness (dKH): 8–11
- Specific gravity: 1.024–1.026
- Adult diameter including spines: large; allow ample open rockwork
- Lifespan: roughly 4–10 years
A large tank with abundant live rock and stable parameters suits this urchin; if grazeable algae runs low, offer dried algae sheets so it does not starve and turn to scraping coralline or coral.
Diet
Diadema setosum is a herbivore that grazes a wide variety of algae common on tropical reefs, including nuisance hair algae. It is largely nocturnal, hiding by day and emerging at night to forage.
Compatibility
It is generally considered reef compatible as an algae grazer, but its long, sharp spines can knock or abrade nearby corals, so it needs space. Avoid housing it with known urchin predators such as triggerfish and pufferfish.