What water parameters does the Long-Spined Sea Urchin need?

The Long-Spined Sea Urchin does best with a temperature of 72–82°F, a pH of 8–8.4.

Is the Long-Spined Sea Urchin aggressive?

The Long-Spined Sea Urchin is generally peaceful and suits a community tank with similarly calm tankmates.

What does the Long-Spined Sea Urchin eat?

The Long-Spined Sea Urchin is a herbivore. It needs a plant-based diet such as algae, blanched vegetables, or spirulina-based foods.

Is the Long-Spined Sea Urchin reef safe?

The Long-Spined Sea Urchin is generally considered reef safe.

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InvertebrateSaltwaterIntermediatePeaceful

Long-Spined Sea Urchin

Diadema antillarum

Also known as: Long-spined Urchin

A bold, spiny reef grazer that keeps algae in check around Caribbean reefs.

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About

The long-spined sea urchin (Diadema antillarum) is one of the most recognizable invertebrates associated with Caribbean and Atlantic reef systems, instantly identified by its dramatically elongated black spines that can extend several times the diameter of its body. Those spines are no decoration. They serve as serious defense, and anyone who has accidentally brushed one knows they break off easily and cause irritation. In the wild, this species is considered a keystone grazer, keeping algae cropped short and allowing corals to compete for space on the reef. Its ecological importance became sharply clear after a massive die-off swept through Caribbean populations in the early 1980s, after which algae quickly smothered many reef areas. In a reef aquarium, this urchin performs much the same role, working over rockwork and substrate in search of algae, particularly at night when it tends to be most active. Despite being listed here as a freshwater invertebrate, Diadema antillarum is exclusively a marine species and will only thrive in a well-maintained saltwater setup. Care is considered intermediate, largely due to its sensitivity to water quality and the practical challenge of cohabiting with its formidable spines.

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At a glance

Type: Invertebrate
Water: Saltwater
Diet: Herbivore
Temperament: Peaceful
Reef safe: Yes

Water parameters

Temperature: 72–82°F
pH: 8–8.4

Care guide

Provide a mature reef aquarium with excellent water quality and stable parameters. This species is sensitive to fluctuations and poor conditions. House in tanks of at least 75 gallons with plenty of live rock for grazing. Feed opportunistically on algae naturally present in the tank; supplement with dried seaweed or algae sheets if grazing opportunities are limited. Avoid copper-based medications entirely, as they are highly toxic. Handle with extreme care or use tools when necessary. Spines are fragile, break easily, and cause painful irritation. Keep compatible with peaceful fish and invertebrates; aggressive feeders or curious tankmates may harass it. Nocturnal by nature, so expect most activity after lights dim. Position rockwork carefully to prevent collapse from burrowing behavior.

Similar species

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Long-Spined Urchin

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Good tank mates

Species that tend to coexist peacefully with Long-Spined Sea Urchin

Golden Head Sleeper Goby

Fish

Valenciennea strigata

Indian Sea Star

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Fromia indica

Frequently asked questions

What water parameters does the Long-Spined Sea Urchin need?: The Long-Spined Sea Urchin does best with a temperature of 72–82°F, a pH of 8–8.4.
Is the Long-Spined Sea Urchin aggressive?: The Long-Spined Sea Urchin is generally peaceful and suits a community tank with similarly calm tankmates.
What does the Long-Spined Sea Urchin eat?: The Long-Spined Sea Urchin is a herbivore. It needs a plant-based diet such as algae, blanched vegetables, or spirulina-based foods.
Is the Long-Spined Sea Urchin reef safe?: The Long-Spined Sea Urchin is generally considered reef safe.