Sea urchins move slowly by crawling with their tube feet or by pushing themselves with their spines
I was snorkeling off the northeast coast of Grand Cayman in the Cayman Islands when I took this photo of a West Indian sea egg. At the time it didn't seem like much, but through the years, I have enjoyed gathering a collection of urchin photos. I find them to be a most interesting class of animals. Echinoidea have a wide range of characteristics across the 950 identified species. Their bodies are typically one to four inches in diameter. Sea urchins move slowly by crawling with their tube feet or by pushing themselves with their spines.
The West Indian sea egg is also known as the white sea urchin. Its scientific name is Tripneustes ventricosus. It is a common sea urchin of the Caribbean Sea, the Bahamas, and the waters of Florida. To increase your chances of seeing this sea urchin, stay in water shallower than 33 feet. Look for seagrass meadows, rubble areas, and shallow rocky reefs, like the one seen in this photo. Smaller West Indian sea eggs will hide in crevices and under rocks during the day.
West Indian sea eggs have a black, dark purple, or reddish brown test that is covered in small white spines that are less than one inch long. The test can grow to be as large as 6 inches in diameter. What is a test, you might ask. A test is a shell-like structure that is found in some spherical aquatic animals. The sea urchin is the most notable, but it is also used to describe the shell of some microorganisms, including testate amoebae and foraminiferans.
The word urchin is an old word for hedgehog, which they resemble. At one point, they were referred to as sea hedgehogs (a name which I think should return!). Sea urchins have a top and a bottom. The mouth is at the base, which is also where its feet are. The anus is at the top of the urchin.
Urchin is an old word for hedgehog
Did you know?
- Sand dollars are a species of sea urchin. They belong to the Irregularia infraclass of urchins.
- The West Indian sea egg feeds on algae.
- The gonads of the West Indian sea egg are a traditional food of the West Indies. In Barbados there is a fishery to harvest the gonads of this sea urchin.
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