Sand dollars are sea creatures. They go by different names too. It is known as the sea cookie or snapper biscuit in New Zealand and pansy shell in south Africa. To put it simply they are flat burrowing sea urchins.
They are also known as sand cakes or cake urchins. They are related to sea urchins and sea cucumbers and starfish too. It is purple and hairy in its prime. It belongs to the order Clypeastroida. They are mostly found in tropical temperate waters.
What are Sand Dollars?
Sand dollars are flat, burrowing sea urchins belonging to the order Clypeasteroida. They are distinguished by their hard skeleton called a test, which is often what beachgoers find.
Living sand dollars are covered in tiny, velvet-like spines that aid in their mobility and feeding. These creatures are found in ocean beds worldwide, primarily in shallow temperate and tropical waters.
Scientific Name
The real name of a sand dollar is Echinoidea, a class that includes sea urchins and their relatives.
Lifestyle and Habitat of Sand Dollar
They reside beneath the low waterline. They can be found beneath sandy and muddy areas. It burrows and creeps through the sediment of the soil. They have spines and on their spines they have cilia.
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It is also seem in these creatures that they have a mouth opening in the center of the star shaped grooves. The mouth is present on the oval surface of the creature.
They can be found in groups in the ocean bottom. This area is preferred by them because it is soft and fit for their reproduction. The sex of these creatures are different. They reproduce through external fertilization.
This means that the gametes are released in water. This process can seem a bit bizarre to us but many animals reproduce through external fertilization. It is common in the animal world.
There are also signs of asexual reproduction among them. This was found in 2008 by the scientists. However they clone themselves because of self defence. This might sound a lot like some sci-fi movie but it is true. This phenomena actually occurs.
If you want to know about this more in detail then you can keep on reading this article. When the sand dollars grow up they do not have much natural predators but sunflower starfish and ocean pouts are some animals that will eat the sand dollars.
The spines on their bodies help them move around in the ocean and protect themselves from the predators. They are fascinating creatures. Let’s learn a bit more about them. This is probably going to be a long article so buckle up your seat belts guys. Here we go.
9 Things You Didn’t Know About Sand Dollars
There are some things that you probably don’t know about the sand dollars but you must. This will make for a very interesting read so make sure that you go through all the 9 points mentioned here in this article.
We have selected good facts for you. So now pay attention as we begin the 9 things you didn’t know about sand dollars. The First fact that you probably didn’t know about the sand dollar is –
1. Sand Dollars Aren’t White When They’re Alive
You might have seen a white skeleton of the sand dollar on the beach. Most people only see the sand dollars after they are dead so they assume they are white in colour but that’s not the case.
The sand dollar is actually reddish brown to purple in colour due to pigments when they are alive. Living sand dollars have spines all over their body. When the sand dollar dies, its skeleton is revealed and it gets bleached by the sunlight.
Its star shape is also revealed due to the falling off of the spines. Thus now you know how the sand dollars actually look when they are alive.
2. Live Sand Dollars Can’t Survive for Long Out of Water
You can not remove a live sand dollar from the beach. It is highly illegal. But the cases obviously differ when it comes to dead organisms.
If you are certain that the sand dollar is dead then you can take it but if you are not then it is better to leave them alone. A sans dollar can’t survive in the sand for long without any water.
They cant breath because of their signature petals which are also known as petaloids can not work outside of the water.
3. They’re Related to Sea Stars and Sea Urchins
We have mentioned in the beginning of the article itself that sand dollars are associated with sea urchins and sea stars. They are kind of like cousins. The sand dollars are also sometimes referred to as irregular sea urchins.
That’s very rude of them if you ask us. The sand dollar is its own animal, they have their own identity! However they are also related to sea cucumbers and starfish.
Sea lilies might also be a distant cousin of the sand dollar. To put it simply they are all related to each other. They are one big happy family if you look at that in a positive way.
4. They Have Many Nicknames
Yes, it is true that the sand dollars have a lot of different nicknames in different regions. However, we are going to state a few of them. We might not be able to state all of them though.
They are known as eccentric sand dollar or sand dollar in the United States Of America. In New Zealand, it is known as sand cake, cake urchin or even sometimes sea biscuit. Those are some weird nicknames to be honest.
They also called them sea cookie or snapper biscuit. In South Africa, they are Known as pansy shell.
5. They Use Their Spines To Eat
What do these sand dollars eat? Well they feast on debris, diatoms, crustacean larvae, small copepods and microscopic algae. They eat through their spines. Their spines are covered with hair-like projections called cilia.
The move the food particles from the sand along their body using the cilia. They move the food to their mouth that is located in the center.
The mouth is on the under side of the sand dollar as we have already mentioned. It takes 15 minutes to grind its food and can take up to two days to digest their food. Talk about a slow eater!
6. Their Holes Serve a Purpose
The holes on the body of this creature serves a purpose. You must know that every part of an organism is there to perform a specific function. They can be seen as a body art on the sand dollars too but they have a much more important purpose than just decoration.
They act as pressure drainage canals. They have a particular name – lunules. It helps the sand dollars to not get washed away in the waves. They can also be used for food harvesting. These are pretty important organs for the sand dollars if you think about it.
7. Their Living Spaces Are Crowded
They are not picky about the living situation. They have the entire ocean floor where they can roam about or even live. But no they choose to stick to each other. It is funny to see how a large number of sand dollars can live in a tiny area. Hundreds and hundreds of sand dollars live in a small space.
This helps then with their reproduction process. Maybe that’s the reason why they all stick together. Since they reproduce by external fertilization, having a lot of them in the same area can increase the success rate of the reproduction.
8. They Have Few Predators
Sand dollars are very lucky because not many animals eat them. They have hard skeletons and very few soft edible parts and that’s the reason why other animals steer clear of them. Well. Almost all the other animals. They do have a few predators in the ocean though.
Some of the predators of sand dollars are as mentioned – ocean pouts, California sheepheads, large pink sea stars and starry flounders. They have the ability to actually digest the sand dollars. This is very unique among the creatures because like we said, the sand dollars have very strong and hard skeletons.
9. You Can Tell a Sand Dollar’s Age by Its Rings
This is kind of similar to telling the age of a tree by counting the number of rings in its trunk. You can also tell the age of the sand dollars by counting its rings. It’s quite fascinating.
Nature is quite fascinating, to be honest. The number of rings increases as they age, which in turn increases their body size. This is a proven fact by the researchers.
Anatomy and Adaptation
The anatomy of a sand dollar is specifically adapted for its burrowing lifestyle. The test is composed of calcium carbonate and exhibits a distinctive pattern that resembles a coin.
Sand dollars have a mouth located on the bottom side of their body, which they use to feed on microorganisms in the sand. They move using tiny tube feet and spines, which also assist in funneling food particles to their mouth.
Habitat and Distribution
Sand dollars inhabit sandy or muddy ocean floors, often in colonies. They prefer shallow coastal waters, usually not deeper than 30 feet.
These creatures are predominantly found in the Northern Hemisphere, in both the Atlantic and Pacific Oceans. They thrive in areas with moderate currents, which help in food availability.
Lifecycle and Reproduction
The lifecycle of a sand dollar involves several stages. They reproduce by releasing eggs and sperm into the water. After fertilization, the larvae develop and undergo metamorphosis before settling on the ocean floor as juvenile sand dollars. They can live for about six to ten years in the wild.
Ecological Importance
Sand dollars play a significant role in their ecosystems. As filter feeders, they help maintain the balance of microorganisms in their habitat. Their presence indicates healthy ocean conditions. Moreover, sand dollars themselves are a food source for various fish and other marine animals.
Threats and Conservation
While sand dollars are not currently endangered, they face threats from habitat destruction, pollution, and climate change. Conservation efforts focus on protecting coastal habitats and maintaining healthy ocean ecosystems.
Characteristics of Sand Dollars
- Appearance: Sand dollars have a flat, round shape with a star-shaped pattern on their upper surface.
- Texture: They are covered in tiny, velvety spines when alive.
- Color: Living sand dollars are typically dark, ranging from purple to brown, while dead sand dollars are white or pale due to sun bleaching.
- Size: Sand dollars generally range from 2 to 4 inches in diameter.
Lower Classifications
Sand dollars belong to the class Echinoidea within the phylum Echinodermata. Some well-known genera include:
- Dendraster: Commonly found on the Pacific coast.
- Clypeaster: Found in tropical and subtropical waters.
- Mellita: Known as keyhole sand dollars, found along the Atlantic coast.
Diet of Sand Dollars
Sand dollars are filter feeders. They consume:
- Plankton
- Detritus
- Algae
- Tiny organic particles
They use their spines to move food towards their mouth, located on the bottom side of their body.
Habitat and Feeding
Where Do Sand Dollars Live?
Sand dollars are commonly found in sandy or muddy coastal areas, typically in shallow waters. They prefer calm, low-energy environments where they can burrow into the sand.
Where Do Sand Dollars Eat?
Sand dollars feed while partially buried in the sand, using their spines to trap food particles from the water column.
What Happens When a Sand Dollar is Opened?
Opening a sand dollar reveals its internal structure, which includes:
- Gonads: Reproductive organs.
- Digestive Tract: Used for processing food.
- Aristotle’s Lantern: A complex jaw apparatus used for grinding food.
Inside a dried sand dollar, you might find five jaw components that resemble doves or stars.
Medical Conditions and Sensitivity
Can Sand Dollars Feel Pain?
There is no conclusive evidence that sand dollars feel pain in the same way humans do. However, like all animals, they have some form of response to harmful stimuli.
Are Sand Dollars Harmless?
Yes, sand dollars are harmless to humans. They pose no threat and are safe to handle gently.
Why is it Called a Sand Dollar?
The name “sand dollar” comes from their flat, coin-like appearance. Historically, people thought they resembled old Spanish or American dollar coins.
Why are Sand Dollars So Special?
Sand dollars are special due to their unique shape, intricate patterns, and the symbolic significance they hold. Many people believe they bring good luck and are considered treasures when found on the beach.
How Much is a Sand Dollar Worth?
While sand dollars can hold sentimental and decorative value, they generally have no significant monetary value. Their worth lies more in their beauty and the joy of finding them.
What Happens if You Find a Sand Dollar?
If you find a sand dollar, it’s important to determine if it’s alive or dead:
- Alive: If it’s dark in color and covered in tiny spines, it’s likely alive. It’s best to leave it in its natural habitat.
- Dead: If it’s white and brittle, it’s dead and can be collected as a keepsake.
Why Are Sand Dollars Dark?
Living sand dollars are dark because of their dense covering of tiny spines and cilia, which help them move and feed.
What’s Inside a Sand Dollar?
Inside a sand dollar are its internal organs, including:
- Gonads
- Digestive tract
- Aristotle’s Lantern
The doves or stars found in dried sand dollars are the remnants of their jaw apparatus.
Can We Touch a Live Sand Dollar?
It’s best not to touch live sand dollars, as handling can harm them. If you do handle one, be gentle and return it to the water promptly.
Is a Sand Dollar Lucky?
Many cultures consider finding a sand dollar to be a symbol of good luck and a sign of good fortune.
Is a Sand Dollar Dead?
Determining if a sand dollar is dead involves checking its color and texture:
- Alive: Dark and covered in tiny, moving spines.
- Dead: White, brittle, and devoid of spines.
Other Interesting Details
Reproduction
Sand dollars reproduce by releasing eggs and sperm into the water column, where fertilization occurs externally.
Predators
Sand dollars are preyed upon by fish, crabs, and sea stars.
Ecological Role
Sand dollars play a crucial role in the marine ecosystem by recycling nutrients and helping to aerate the sediment.
Conservation
While not currently endangered, sand dollars are affected by habitat destruction and water pollution. It’s essential to handle them responsibly and support conservation efforts.
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Conclusion
Thank you so much for giving this article your precious time. It is always fun to know more about different kinds of creatures that exist with us in our ecosystem. Some of you might not have even heard of sandy dollars before today.
The world is full of unique and interesting creatures. We still need to find many species and many creatures. It’s true that nature will never cease to surprise us.
So if you liked the article be sure to tell us about it. Do share it with your fellow friends. Thank you and have a nice day. We enjoyed spending time with this article. Hope you did too.
