The Sand Dollar

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The sand dollar is a marine invertebrate, a living animal, closely related to the starfish, sea lily, the sea cucumber and the sea urchin. Sand dollars come from the Echinoids class, which means "spiny skinned creature."

Sand Dollar, invertebrate having a flat, circular outer shell. The common sand dollar of the northeastern United States is found on sandy bottoms in comparatively shallow water.

The size of the adult shell is about 8 cm (or 3 inches) in diameter on the average and has many small perforations that form a symmetrical petal-like design. You can find larger ones, and tiny little baby ones as well as any size in between.

The entire shell is penetrated by many small, brown spines that give the shell a velvety appearance and enable the animal to move about.

By the time a sand dollar washes up on a beach, it is usually no longer living, and only its shell remains.

Sand dollars obtain food by using their spines and tube feet to engulf sand from which they extract minute plants and animals.

Sand dollars belong to a phylum (family) of marine animals known as echinoderms, which inhabit all the world's oceans and can live in both the shallow and deep-ocean floor.

Scientific classification: Sand dollars belong to the order Clypeasteroida of the class Echinoidea. The common sand dollar of the northeastern United States is classified as Echinarachnius parma.

I believe the Western Sand Dollar to differ from the "Keyhole Sand Dollar" found on the Eastern shores. It tends to not have the five "keyholes" in the shell, and is round, rathers than having those decorative little indentations around the edges.

Though each one has it's own beauty.

The Legend of the Sand Dollar

There's a lovely little legend
That I would like to tell,
Of the birth and death of Jesus
Found in this lowly shell.

If you examine closely
You'll see that you find here,
Four nail holes and a fifth one
Made by a Roman's spear.

On one side the Easter Lily,
Its center is the star,
That appeared unto the shepherds
And led them from afar.

The Christmas Poinsettia
Etched on the other side,
Reminds us of His birthday
Our happy Christmastide.

Now break the center open
And here you will release,
The five white doves awaiting
To spread Good Will and Peace.

This simple little symbol
Christ left for you and me,
To help us spread His Gospel
Through all Eternity

Another Legend of the Sand Dollar

The legend of the sand dollar first began in Maine, where children were taught to believe that sand dollars are pressed sand.

Another legend is that they were money for mermaids to use.

Many think that finding a Whole Sand Dollar as a very, rare and lucky thing to do.

There are some that think of them as a gift from God, or a sign from the Heavens above.

They are found along the beach, usually at low tide, in the wet sand.

And they will look like the picture below, when still in the sand.

There is a Myth or misconception, that picking up a sand dollar and keeping it, is wrong because it is a "live animal".

This is not entirely true, you will definately be able to tell a live Sand Dollar from one that has been dead for a while.

A "live Sand Dollar" will have a very fuzzy look to the top of it, and tiny little spines on the bottom.

I like to throw these back to sea, thinking I am saving them, but most likely they are already dying if they end up on the beach. But I would recommend not picking them up or taking them home.

A "dead Sand Dollar" will be smooth on both sides, and usually a lot whiter in color.

Most beaches and state parks have strict rules against taking any live sea life from their home, so please honor those laws.

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Preserving Sand Dollars

In order to preserve a sand dollar you must first soak it in fresh water. You can follow the steps below to keep your sand dollars to be treasured:

1. Place your sand dollars into a bucket of fresh water. This water will turn a brown-red color & after a short time begin to smell thus it is important to change the water frequently. If time is of the essence just continually flush them in water until the water remains fairly clear.

2. Your next step is to soak them in a solution of chlorine bleach & water. Mix the solution in the following ratio: 3 parts water to 1 part bleach. Soak them for 15-20 mins. only.

3. Rinse the sand dollars off under running water for at least 2 mins.

You must not soak them overly long in the bleach-water because it will make them become brittle & they will begin to crumble apart. They can also turn yellow from too much bleach.

Each soaking in bleach weakens the sand dollar's exoskeleton a little more so it is not recommended you do this more then once.

If this process does not whiten your sand dollars then it is best to allow the sun to bleach them the rest of the way or you may simply spray them with white paint or lacquer.

Another way to clean & sun-bleach sand dollars is to place them on an ant mound. The ants will clean them & the sun will bleach them. This method takes as long as a week so if you are in a hurry this is not the method for you.

Now you may harden these treasures by mixing a white glue & water in equal parts. Use a sponge brush & completely coat each sand dollar with this mixture. Allow them to dry completely. Once your sand dollars are dry you may use them in a wide variety of craft projects or in displays.

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The Sand Dollar is considered a suspension feeder and feeds on suspended organic particulate matter in the water currents.

Various specialized spines, tube feet, mucus-secreting glands and the pedicellariae - small pincher-like organs with moveable jaws, are involved in feeding.

The spines on the aboral side are club-shaped and covered with cilia. When small organic particles and organisms flow onto this surface, little eddies are created and particles become trapped by mucus secreted on the spines.

They are directed by these club-shaped spines and cilia to the margins and around to the oral side to the food grooves, where they move in mucus streams that lead to the mouth in the center.

Larger suspended particles may be held by sucker-tipped podia and transported to the food grooves. For living prey such as crustacean larvae and small copepods, the spines on the oral side converge and enclose it into a little tent-like cone, where it is passed to a food groove by the jaws of the pedicellariae. Sand is ingested with the food and it is thought that this is deliberately done to use for weight, for their stability in the sand.

The Western Sand Dollar is able to feed in this manner because of its eccentricity, which allows it to bury itself "standing up" obliquely in the sand. This is their feeding position, parallel to the surge current with the anterior end buried (Lawrence 1987). By positioning themselves closely together, they may exploit their hydrodynamic shape and influence the current flow past their bodies. It is likely that this is the reason they form densely packed beds of several hundred individuals per square meter. In light currents, they may stand perpendicular, lay flat, or even bury themselves (Jangoux and Lawrence 1983).

Reproduction

Reproduction is sexual and the Western Sand Dollar reaches sexual maturity between 1 and 4 years of age.

The swelling of the gonads in May marks the beginning of the major spawning period, which lasts through July or August.

The female Dendraster discharges the eggs already ripe (meiosis already occurred) through her gonopores and are fertilized externally by the male, who protrudes his genital papilla from his body wall to increase the distance that the sperm can reach the eggs.

Within 2-4 days, four-armed pluteus larvae develop and become a part of the floating zooplankton. Adult Sand Dollars will eat their own larvae but not their eggs, due to a protective jelly coating. Individuals probably spawn multiple times. Females can produce over 350,000 eggs per year.

Brooding, or the association of the juvenile with the female parent, is not common in echinoderms because it would decrease reproductive productivity.

The larvae may travel quite a distance with the currents and do not necessarily stay near the parent bed group.

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If you look at the front of a Sand Dollar, which is called the aboral side, you will see the five petals of the flower and those tiny little holes on the front, called gonopores.



A flower-like pattern is composed of pore pairs where specialized tube feet perform gas exchange.



At the center is the madreporite - a perforated platelike structure that forms the intake for their water-vascular system, and adjacent to this on the interambulacra, the genital pores. Radiating out from the genital pores are the five flower petals, which represents the ambulacral radii.

On the back of the Sand Dollar, which is called the "Oral Side" is the mouth in the center, the hole in the middle.



And the tiny hole at the bottom, is well...the sand dollars bottom, where wasted is excreted.

The groves are food groves.

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