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Sea Urchin

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Sea Urchin Facts

Five groups that classify all living things
A group of animals within the animal kingdom
A group of animals within a pylum
A group of animals within a class
Common Name:
Most widely used name for the species
Sea Urchin
Scientific Name:
Comprised of the genus followed by the species
The area where the animal first came from
3-10cm (1.2-3.9in)
Water Type:
Either freshwater, brakish or salt
Optimum pH Level:
The perfect acidity conditions for the animal
Life Span:
How long the animal lives for
15-200 years
Conservation Status:
The likelihood of the animal becoming extinct
The colour of the animal's coat or markings
Skin Type:
The protective layer of the animal
Favourite Food:Algae
The specific area where the animal lives
Rocky ocean floor and coral reefs
Average Clutch Size:
The average number of eggs laif at once
Main Prey:Algae, Fish, Barnacles
Other animals that hunt and eat the animal
Fish, Birds, Crabs, Sea Otter
Special Features:Small stinging structures and claw-like mouth

Sea Urchin Location

Map of Sea Urchin Locations

Sea Urchin

The sea urchin in found across the ocean floors worldwide, but rarely in the colder, polar regions. Sea urchins are commonly found along the rocky ocean floor in both shallow and deeper water and sea urchins are also commonly found inhabiting coral reefs.

There are nearly 200 different species of recognised sea urchin, that come in all shapes and sizes. Some sea urchins are covered in long thin spikes where others have a hard shell that is made up of chalky plates. The red sea urchin is the longest living creature on earth, with some living more than 200 years.

Sea urchins are omnivorous animals and therefore eat both plant and animal matter. The sea urchin mainly feeds on algae on the coral and rocks, along with decomposing matter such as dead fish, mussels, sponges ans barnacles.

Sea urchins are preyed about by many predators that inhabit their marine environment, but also those animals that don't. The main predators of the sea urchin are crabs, large fish, sea otters, eels, birds and humans. In some countries, certain species of the sea urchin are hunted and served as a delicacy.

Sea urchins have a round shaped body and with long spines that come off it. The spines of the sea urchin are used for protection, to move about, and to trap food particles that are floating around in the water. Sea urchins have five paired rows of tiny tube feet which are found amongst the spines. The feet of the sea urchin have suckers which help the sea urchin to move about, capture food, and to hold onto the ocean floor.

Sea urchins also have little claw-like structure among their spines which the sea urchin uses for protection. These structures (known as pedicellarines) are small stinging structures that are not only used for defence and obtaining food, but are also vital in keeping the body of the sea urchin clean.

The mouth of the sea urchin (known as the Aristotle's lantern), is found in the middle on the underside of the sea urchin's body and has five tooth-like plates for feeding. The anus of the sea urchin is located on the top of the body. As with other echinoderms, sea urchins do not have a brain and instead rely on their water-vascular system which is like a circulatory system and comprises of water-filled channels that run through the body of the sea urchin.

Sea urchins spawn during the spring, and the female sea urchin releases millions of tiny, jelly-coated eggs into the water that are then fertilised by the sperm of the male sea urchin. The tiny sea urchin eggs become part of the plankton and the sea urchin babies (larvae) do not hatch for several months. The sea urchin young will not become large enough to retreat from the plankton and down to the ocean floor until they are between 2 and 5 years old.

Due to dredging on the ocean floor and pollution in the water, the sea urchin populations are declining and the sea urchin and today thought to be threatened with extinction.

Sea Urchin Comments

Gabby c
"I watched Taylor swift and Ellen talking about sea urchins so Taylor swift Is. terrified she hates them she says if you go to the corbinian I love Taylor swift "
"how do they communicate?"
Kris leach
"this is really cool . I love it !"
"where are they found ?"
"Who discovered them? When were they discovered?"
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First Published: 21st December 2009, Last Updated: 9th January 2017 [View Sources]

1. David Burnie, Dorling Kindersley (2008) Illustrated Encyclopedia Of Animals [Accessed at: 21 Dec 2009]
3. Dorling Kindersley (2006) Dorling Kindersley Encyclopedia Of Animals [Accessed at: 21 Dec 2009]
4. Richard Mackay, University of California Press (2009) The Atlas Of Endangered Species [Accessed at: 21 Dec 2009]
5. Tom Jackson, Lorenz Books (2007) The World Encyclopedia Of Animals [Accessed at: 21 Dec 2009]

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