Safekipedia

Sea urchin

Adapted from Wikipedia · Explorer experience

A spiny sea urchin (Diadema setosum) swimming in the clear waters off Zanzibar, Tanzania.

Sea Urchins

Sea urchins are small, round sea creatures that live in oceans all around the world. They have a hard shell covered with sharp spines, which makes them look a bit like little hedgehogs. Sea urchins move slowly using tiny tube feet on their shells.

These creatures love to eat algae, which are like plants in the water. They are found on the ocean floor, from shallow areas where you can see them at low tide, to very deep waters. Sea urchins have been around for a very long time, with fossils dating back over 450 million years ago!

Sea urchins are part of a special group of animals called echinoderms. This group also includes starfish and sand dollars. Like these friends, sea urchins have a special balance called five-fold symmetry. This means their bodies have five equal parts coming from the center.

People sometimes keep sea urchins in aquariums because they help control algae. In some places, people also eat the soft parts inside sea urchins, called roe. Scientists study sea urchins to learn about how animals grow and develop, because their eggs are easy to see and observe.

Images

A close-up of a purple sea urchin, Paracentrotus lividus, found in the Mediterranean Sea near southern France.
A live sand dollar trying to bury itself in beach sand.
A close-up of pencil urchins, marine animals found in the Philippines, showcasing their spiny texture against a black background.
A detailed diagram showing the anatomy of a sea urchin, helping us learn about marine life.
A close-up of a sea urchin, showing its spiny exterior and unique anatomy.
A close-up view of Mediterranean sea urchins showing their intricate calcite structure under illumination.
A close-up view of a sea urchin named Echinus esculentus, showing its spiky exterior.
A close-up of a sea urchin from the north shore of Cuba, showing its spiny body and anatomical zones.
A close-up view of the inner surface of a black sea urchin's shell, showing its unique plate structure and tiny holes for tube feet.
A close-up view of Echinodiscus tenuissimus, a small sea urchin found in Bali, Indonesia.
The shell of an imperial sea urchin, a fascinating marine creature from New Caledonia.
A close-up pattern of a sea urchin shell, showing its spiky and textured surface.
A close-up of a beautiful sea urchin shell, showing its spiky and textured surface.

Related articles

Algae

This article is a child-friendly adaptation of the Wikipedia article on Sea urchin, available under CC BY-SA 4.0.

Images from Wikimedia Commons. Tap any image to view credits and license.