Sea urchins identification page

A very common pin-cushion looking creature

Like sea stars, sea cucumbers and brittle stars, sea urchins are part of the Echinoderms phylum. With their spherical body covered moveable spines, they are among the most iconic inhabitants of the sea.

More than 900 species of sea urchins (or Echinoidea) inhabit the world’s seas and oceans, with variable coloration and shape. They are easily found when snorkeling, moving slowly on the bottom using their tube feet.

Caribbean white sea urchin
Collector urchins often cover themselves with fragments of shell, coral, and seagrass. Here, two Caribbean white sea urchins in Petite Terre, Guadeloupe.

Swimmers are often afraid of being stung by sea urchins, which can cause serious injuries when not treated.

Some tropical urchin species are also poisonous, like the fire urchins, collecting urchins, and the flower urchin, whose venom can cause serious reactions. Learn to identify it: its tube feet often cover its entire body, masking its spines.

Where to spot sea urchins when snorkeling?

Sea urchins are seen almost everywhere in snorkeling, including in tidal pools and at very shallow depths.

The red pencil urchin, with very thick and rounded spines, is very photogenic. It is found throughout the Indo-Pacific, where it is very common, especially on the reefs of Hawaii.

Red pencil urchin in Hawaii
The red pencil urchin is an awesome subject for underwater photography. Here, in Napili Bay, Hawaii.

Long-spined sea urchin, with their very small body (or “test”) and their very long spines (which can reach almost 30cm) are easy to identify. There are 3 species of long-spined sea urchin distributed in the different tropical seas.

Collector sea urchins (genus Tripneustes) have the ability to cover themselves with coral or algae fragments to better hide. In the Mediterranean, purple and black sea urchins are easy to see in rocky areas.

Caribbean & Western Atlantic sea urchins

Indian & Pacific Oceans sea urchins

Eastern Pacific Ocean sea urchins

Mediterranean and Eastern Atlantic Ocean sea urchins

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