By Blane Perun
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Strongylocentrotus purpuratus, more commonly known as the purple sea urchin, is a sea urchin that is quite small. Sea urchins are small and round with spines all over their body. These sea animals live on the sea floor, mostly in rocky areas, and may be found in very shallow and very deep water.
Sea urchins are found worldwide, however the purple sea urchin is found from the Baja Peninsula to Canada, in the Pacific Ocean and off North America’s west coast. The purple sea urchin is an invertebrate and it travels at very slow speeds along the sea floor.
The purple sea urchin measures approximately 3 and ¼ inches across when mature. The spine is not even half an inch long. When young, the purple sea urchin is actually green. However, as it matures it turns to a lilac color or even a darker, deep red purple. Interestingly, their "shell", which is rally plates on their hard skin, is known as a test. Along their body sea urchins have spines, very much like a porcupine.
These spines have multiple functions including trapping algae to moving as well as for protection. Additionally, the purple sea urchin as well as all other urchins have tubular feet. They are transparent and sticky so they can easily grip the ocean floor. Many people assume that sea urchins have a brain, but they do not and neither do any of the echinoderms. The sea urchin’s mouth is underneath its round body while the genitals and anus are on the sea urchins top part.
Some of the foods the sea urchins eat include dead fish, algae, plants, animal and decaying matter, barnacles, mussels, sponges, and the like. Crabs, sea otters, people, fish, birds, snails, and even sunflower stars are all predators of the sea urchin. When it comes to the purple sea urchin and reproduction the process is not intimate in the least. Instead, external fertilization occurs by the female releasing millions of small eggs. The tiny eggs begin to develop and become larvae. They swim through the water with zooplankton and it takes months before they actually become juvenile sea urchins. Sea urchins are not capable of reproduction until they are at least two years old and in many cases up to five.
It is fascinating to see pictures of the purple sea urchin because they really range in color from light purple to a dark red purple. Many people mistakenly believe sea urchins are only black or brown, but they can actually be a wide range of colors including purple. They are part of the class and order of Echinoidea as well as the family and genus strongylocentrotidae. The sea urchin was named more than 150 years ago.