Long-spined sea urchin

Diadema antillarum

The long-spined sea urchin is a dark tropical reef grazer with exceptionally long, delicate spines. By eating algae, it creates bare surfaces where corals can settle.

Not a fish · an aquatic neighbor

Water

Saltwater

Shallow tropical coral reefs, reef flats, lagoons, and rocky coastal bottoms.

Temperature

Range not established

A dependable species-specific wild temperature range was not established from the reviewed sources.

Size

Body usually about 5–10 cm (2–4 in) wide; spines can be several times longer

The body is about the size of a small orange.

Lifespan

Not established in the wild

Life expectancy varies with place, conditions, and what scientists have been able to observe.

01 · Signature adaptation

What does it do?

It moves mostly at night or under shelter, using tube feet and spines. It is a keystone herbivore whose historic Caribbean die-offs allowed algae to spread across reefs.

Its superpowerIts long spines deter predators while its mouth scrapes algae from reef rock.

02 · Home coordinates

Where does it live?

Caribbean Sea and adjacent western Atlantic tropical reefs.

Regions: Caribbean Sea · Bahamas · Florida · western Atlantic

03 · The menu

What does it eat?

It grazes algae from hard reef surfaces and helps prevent algae from overgrowing corals.

Herbivore: macroalgae, turf algae, coralline algae.

04 · Remember this

Two wow facts

Reef lawnmower

Its grazing removes algae and opens clean surfaces for coral larvae.

Sources [1] [2]

Massive die-off

A disease event in the early 1980s eliminated up to 95–99 percent of individuals in many Caribbean locations.

Sources [1]