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What is a Sand Dollar?

Sand dollars are closely related to starfish.
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  • Written By: R. Kayne
  • Edited By: O. Wallace
  • Last Modified Date: 11 October 2014
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A sand dollar is a marine animal named after its flattish, round shape that resembles a large coin. This type of animal belongs to a class of animals known as Echinoids and are close relatives of the sea urchin and starfish. Many people are familiar with sand dollars that have washed up on the beach, becoming bleached by the sun to a light sandy color. When this animal is alive however, it is darker in color and covered by tiny, mobile spines.

A sand dollar has a characteristic 5-petal design on its back produced by sets of large pores. When it is alive, rows of tiny tubular feet extend up through the pores. These respiratory stalks or podia act as gills by flushing water through the sand dollar to keep it oxygenated.

Most species of sand dollars live on or just under the seabed in muddy or sandy areas at depths of about 30–40 feet (9-12 meters). The tiny spines covering their exoskeletons are covered with minute hairs, or cilia. On the underside of the animal, these spines and hairs relay food particles along grooved lines in the hardened skin that lead to a central hole where the mouth is located. The spines and hairs also aid in movement along the sea floor.

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The small, circular opening in the underside of the sand dollar hardly seems sufficient for a mouth, but this animal does have teeth. If you shake the bleached skeleton of a sand dollar (called a test) you’ll likely hear something rattling inside. Break open the test and you’ll find several small white pieces that served as teeth.

Sand dollars are usually found in large groups and have limited enemies due to the tough outer shell along with negligible inner meat. Some predators of these animals include starfish, snails and certain fish. The animal gives birth by releasing larvae through the top pores of the exoskeleton. The young are carried along ocean currents for miles, and those that survive go through many stages before developing the outer calcium-hardened shell of the adult sand dollar.

Sand dollars are found in coastal waters all over the world. People often collect them for their beauty, and the shells are also commonly found in decorative sea-themed art.

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FirstBase
Post 5

The legend of the sand dollar is as unique as its counterpart in Christian culture.

With its five slits, you can find the correlating nail holes on Christ's body as he hung from the cross.

When you break open the sand dollar's center, you'll find five white doves flying free, expressing good will and peace to all.

I don't know of any other natural living being with such a strong, spiritual story.

SarahG
Post 4

I was on a southwestern Florida island last weekend and was stepping on what felt like hundreds of sand dollars while in the ocean.

We weren't in more than 3-5 feet of water (not 30-40 feet as the article mentions) and the sand dollars literally covered the sandy bottom. Could it be that sand dollar facts may be different depending on the ocean you are swimming in?

When I bent to pick up a few of them, I could see they were all slightly grey or dark beige and very alive. It's illegal in Florida to collect sand dollars while they are alive.

chicada
Post 3

We live in Portland Oregon, so we get very little snow during the wintertime. To liven up the holidays, we go crab fishing around thanksgiving and Christmas, and we make sand dollar Christmas ornaments. I let my kids paint the sand dollars they have been collecting throughout the year so we can hang them on the tree. It is the perfect indoor activity for the normally wet and dreary holiday season.

parmnparsley
Post 2

@submariner- Sand dollars live just below the average low tide line. I used to dig for clams in Inverness with my grandfather and I would often find the sand dollars creeping slowly towards the ocean at low tide. From what I have seen, they prefer sandy areas because they burrow under the sand where they are safe.

They are neat little creatures, and I have seen them as pets in salt-water aquariums. Taking your daughter out during low tide to see all of the unique creatures that are stranded in the tide pools and on the beach would be a fun way to teach her about the ecosystem of the intertidal zone. It is much more fun than buying sand dollars at a souvenir shop.

submariner
Post 1

When I was a kid, I used to pick sand dollars from the beaches in California. How deep do sand dollars normally live? Are they something that I could take my daughter to find in tide pools or do they live in deeper water? This was a great article...it brought back memories and gave me something to teach my daughter about.

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