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
Most widely used name for this species
The name of the animal in science
The area where the animal first came from
How long (L) or tall (H) the animal is
Either freshwater, brakish or salt
|Optimum pH Level:|
The perfect acidity conditions for the animal
How long the animal lives for
The likelihood of the animal becoming extinct
The colour of the animal's coat or markings
The protective layer of the animal
The preferred food of this animal
The specific area where the animal lives
|Rocky ocean floor and coral reefs|
|Average Clutch Size:|
The average number of eggs laid at once
The food that the animal gains energy from
|Algae, Fish, Barnacles|
Other animals that hunt and eat the animal
|Fish, Birds, Crabs, Sea Otter|
Characteristics unique to this animal
|Small stinging structures and claw-like mouth|
Sea Urchin Location
The sea urchin is 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 and 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.
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First Published: 21st December 2009, Last Updated: 8th November 2019
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