Sea urchins can be many colors and sizes. They vary from purple, green, black, brown, white, or red. In size they range from two to four inches in diameter including the spines. Urchins are usually found at the bottom of the ocean, near the rocky shore. They are called "hedgehog of the sea".
Other than the spines on the sea urchin are pedicellariaes which are three-jawed pincers, some having poison glands. Pedicellariaes are used for defense and cleaning the body of the sea urchin. They also have movable spines, some solid or hollow. The hollow usually filled with poison, and used for locomotion and protection. Sea urchins also have tube feet which are hollow and muscular projections. They are very flexible and extend beyond spines. Tube feet are used to grip objects on the ocean floor. The tube feet pick up things like small rocks, bits of shell, and seaweeds for camouflage. The sea urchins arrange the objects around their body to hide from enemies.
Sea urchins also have teeth, they have an undersurface containing the mouth. They use their teeth to bore holes in rocks and use them as hiding spots. Their teeth and spine help make the rocks bigger for the sea urchin to squeeze into it. This means it is a big enough home for them, but it is small for visitors and enemies.
Sea urchins have the longest spine of any echinoderm. They have bony plates below their skin, and when they come together they form a skeleton called test. Not all of them have their spines attached, it sometimes has tiny holes to wiggle their tube feet through. This is a little research I did on sea urchins, I hope you learned something new about them.
I thought this blog helped me learn a lot more about sea urchins. I learned that they actually had teeth or even a mouth. It was amazing to see that there wasn't just one type of spine on the sea urchin. It is much more complex than it seems. Researching this has made me want to learn more about these amazing creatures.
"The Ocean." National Geographic. N.p., n.d. Web. 01 May 2013.
"Animal Planet." Animal Planet. N.p., n.d. Web. 01 May 2013.
