Species group · Sea urchins

Urchins

WAnimals has 4 species of urchin, spread across 4 families (Diadematidae, Echinidae, Spatangidae, Strongylocentrotidae).

4 species
4 families
146 countries
77 parks
Length
5 cm – 17.6 cm
Lifespan
8 – 20 years

Ranges calculated from the entries that record the figure, not from all 4.

All 4 species of urchins on WAnimals

Each one has its own full entry. This group does not replace them: it brings them together.

Conservation status

3 Not Evaluated1 Near Threatened

No species documented in this group is genuinely at risk according to the IUCN, with the data available today.

See the global conservation status

Where they live

Recorded in 146 countries. The ones with the most species in the group:

Where to see them

Did you know…

  • It scrapes algae off rocks with its Aristotle's lantern, made up of five calcareous teeth.

    From Edible Sea Urchin

  • A large female can release as many as 20 million eggs.

    From Edible Sea Urchin

  • It is the only sea urchin listed as Near Threatened by the IUCN.

    From Edible Sea Urchin

  • Its long hollow spines break off easily inside the skin on contact and release a toxin that causes intense, lasting pain.

    From Long-spined Urchin

  • In 1983 and 1984 a disease of unknown origin killed more than 95 % of the Caribbean population in little over a year, and without its grazing many reefs shifted from being dominated by coral to being dominated by algae, a change they have still not recovered from.

    From Long-spined Urchin

  • In 2022 a further mass mortality, attributed to a ciliate protozoan, struck the recovering populations again.

    From Long-spined Urchin

  • It has lost the radial symmetry typical of echinoderms and regained a bilateral one, with a front and a back, an adaptation to a buried and mobile life.

    From Purple Heart Urchin

  • It maintains a clean-water shaft to the surface using specialised tube feet that build and clean the tunnel.

    From Purple Heart Urchin

Ecosystems

See every species group · Explore the species one by one