Sand dollar
The sand dollar or Dendraster excentricus is one animal that continues to surprise me every time I see it. Long before I started learning about the ocean and marine life, I remember seeing faded-white sand dollar shells (former sand dollar endoskeletons) and not thinking much of them. Now I find sand dollars fascinating because they are just so strange. Drum roll please…here are seven swinging sand dollar facts:
1. Sand dollars live in…you guessed it! The sand. Typically, the species Dendraster excentricus is found close to shore in the low intertidal zone to as deep as 30 feet from Alaska to Baja California. (The low intertidal zone is the area close to shore that is usually covered with water except at very low tides.)
2. For sand dollars, living right next to each other in very large groups or beds is the way to go. Sometimes there are neighborhoods of sand dollars that are several square feet (suburban dwelling) and others stretch for miles across the sandy ocean floor (urban dwelling). (Here’s a good photo of sand dollars hanging out together.)
3.There are many species of sand dollars living around the world with a variety of common names including sea cookie and sand cake. Sand dollars also come in a variety of colors such as green, blue or black; the local California species, Dendraster excentricus, is purple.
4. Sand dollars are members of the phylum Echinodermata, which means they are echinoderms and closely related to sea stars, sea urchins and sea cucumbers.
5. It’s hard to believe, but this flat and round-shaped creature is designed for burrowing in the sand. Their bodies are covered with tiny spines (similar to a sea urchin’s spines but super small) that they use to dig. Once they’ve burrowed into a good position (see above photo) sand dollars keep their butt end above the sand’s surface to capture food.
6. The feeding strategy of sand dollars is fascinating. Their bodies are covered with tiny appendages to capture food particles small and large. Tiny cilia (extra small hairs) on the sand dollar’s spines sweep up small bits of food and tiny tube feet adeptly collect larger food pieces. Once food is caught the tiny appendages on the sand dollar work together to sweep food towards the mouth, which is located at the center of the five-petal flower pattern on bottom. The mouth has a five-toothed set-up called Aristotle’s lantern for chomping food. (Five pattern symmetry is a characteristic of echinoderms, sea stars have five arms, etc.)
7. Sand dollars reproduce by spawning; male sand dollars release sperm and female sand dollars release eggs into the water during spring. Reproduction is assisted by sand dollars living so close together. In fact, this post is very timely since it’s May 1st, coinciding with the beginning of sand dollar spawning season that continues through July. Sand dollars begin their lives as larvae and go through several larval stages before developing skeletons and settling on the ocean floor as the first step to adulthood. An adult sand dollar is about three inches in diameter and lives approximately eight years.
(Note: The above sand dollar facts are for the species Dendraster excentricus, other sand dollar species may have slightly different adaptations depending on where they live in the world.)
These sand dollars are indeed swinging! I love how they live in gated communities, and any day with a reference to cilia is a good day! Thanks, OWT.
I stay in a small village on the west coast of Scotland and spend many days with my daughter at the beach looking for marine life in small rock pools but most of the beach is sand and a few weeks ago i found one of these sand dollars which was shaped as round and it was floating in shallow water at the edge. im pretty sure it was a sand dollar but when ive googled it all it says is that they are from Calirfonia. Do you get these creatures in the sea’s of Scotland, UK and why was it floating?
Hello RMillan,
There are many different species of sand dollars found throughout the world and I’m guessing you found a species local to Scotland’s coast. There may be more information available on the California species because it has been studied more, but it’s definitely not the only species out there. I recommend contacting the National Aquarium in Devon and ask them what species of sand dollars live along the UK coast.
A floating sand dollar usually means a sand dollar close to the end of its life cycle. It’s possible that a strong wave or predator knocked the sand dollar loose and it floated off or it died and was washed ashore, most likely it was the later scenario. I hope this answer helps!
OMG THIS SO HELPED ME WITH MY PROJECT THANKS SO MUCH
THX U HELPED ME A LOT WITH MY PROJECT
Me too!!!!
thx!
🙂
My family visited Pacific Beach, Wa. recently. We have often found sand dollars on our Pacific Coast. This trip we saw what appeared to be the impression of the underside of the Sand dollar on the surface of the sand. Can you tell us what this is??????Thanks
thanks so much needed that very much
My ever curious nephew got a couple of sand dollars from the Easter Bunny & asked me if it was a shell or what. So thank you for these facts so I can sound smart!!
Glad I could help Elizabeth!
I’ve never found a reference to what I’m about to tell you, but I saw it with my own eyes so I know it’s true.
I was scuba diving alone at the south end of La Jolla Shores trying out a new wet suit (No lectures, please.). It was December 26, 1990, according to my log book. Not sure of the exact spot, but it was somewhere in front of the country club. The water was extremely calm. Almost no swells, and the “waves” amounted to nothing more than a single four inch pipe breaking onto the sand. I was a hundred yards or so from the shore and depth was maybe 10-15 feet. I didn’t have a camera, unfortunately. What I saw was sand dollars, probably a couple hundred of them, all up on edge with grooves in the sand behind each one. It appeared as if they were all rolling toward the shore. They were not moving fast enough for me to remain interested in timing them, but the evidence seemed pretty clear that they had made the grooves themselves. There was no one else out there with me and, being early in the morning, there were few people on shore, so I have no witnesses.
I’d be curious to know if anyone else has seen something like this. So far I’m the only one.
What a great sighting Steve! I’m sure you’re right, it only makes sense that sand dollars would leave grooves in the sand as they move along. I’ll ask around to see if other scuba divers have seen this. In the meantime, if there are any scuba divers who have seen something similar please weigh in!
We live near the Gulf Coast in Alabama and have seen and collected various sand dollars. My granddaughter was visiting and came home with two that were black. We had never seem any black ones in the gulf before. Are they native to this area too or is this rare?
Hi Helen, Yes, the sand dollar is common to Gulf Coast area. Based on the research I did, it looks like it’s commonly referred to as the keyhole sand dollar and its scientific name is Mellita tenuis. I hope that helps!
We just came back from the Destin area of Florida. While there, we watched a man and his son “hunting” sand dollars. They had a large bag of them. Maybe a hundred or so. Are there that many sand dollars that “hunting” them is okay?
Hi Patty, I’m not familiar with what the conservation status of sand dollars is in Florida, but do you know if they were live sand dollars or just shells? Either way, I will do more research and try to find more information on the Florida Fish and Wildlife
Conservation Commission website. Thanks!
When is the best time to find a sand dollar in the golf ocean off padre island?
Hi Tammie, There’s the potential to find sand dollars any time of the year on Padre Island, but the best chance for beachcombers is after big storm events. Please visit this website for more information: http://onpadreisland.com/north_padre_island_sea_shells.aspx
March 18,2015 I walked my beach locate east side Harstine island, southern Puget Sound on Case Inlet, Washington state. I was searching for the white dead sand dollars which I never have problems finding.Except this time I only found 8. Normally I can bring home buckets. Is there a time of year more prevalent for the white ones. Lots of live black purple ones out about a two foot above tide.I haven’t searched for them this early in the year, mainly summer months. Reading your information, I wonder if the hotter summer months make a big difference for the white dead ones, but if the case why only 8 on my entire beach?
I think it is extremely ignorant of people to “hunt “or collect sand dollars or any other living creature they find @ the beach, NO MATTER WHAT THE STATUS! They have a right to live. LEAVE ONLY FOOTPRINTS, TAKE ONLY PICTURES!
Majority of people I’ve ever seen only take the shells of the sand dollars.
Hi Lisa, It’s tricky with sand dollars, the sand dollar and its shell are one. Live sand dollars are usually a color, here in California they’re purple. A white sand dollar shell usually indicates a dead animal, but in general it’s still better to leave ocean areas as you find them, unless you are picking up trash – then that’s always a good thing.
Wrong, wrong, wrong Lisa. I am a West Coast Florida native and I can personally testify that many, many, many idiots (mostly ignorant tourists) help themselves to hundreds of these delicate and awesome LIVING creatures just so they can take them home and show them off to family and friends. It’s not long before the sand dollars end up in the garbage. It’s truly sickening. On our local beaches (Clearwater, Treasure Island, St. Pete Beach, etc) you used to be able to see Starfish too but because of ignorant, selfish morons, it is now extremely rare to spot one. The bottom line? Look and enjoy the wildlife and sea creatures but leave them where they belong…..in nature, not in a curio or sold on E-Bay , or in a garbage can. At this rate, due to our greedy nature, there won’t be any Sand Dollars left in the distant future.
I read somewhere the sand dollar stand vertical to feed and is flat for locomotion
What a fascinating post. Just home from a walk to Sand Dollar Beach here in Nova Scotia. Cold Spring day. We saw some white Sand Dollar shells (do I call them “shells” ?) but what was fascinating was we spotted several of them along the shore. Live ones ! It was low tide. They were brown with feathery edges, lying flat on the wet sand. They seemed to be pushing themselves along flat on the sand.
Hi Sybil, Yes, you can call them white sand dollar shells. That’s awesome you were able to see live sand dollars as well, they sound beautiful! Ocean animals are amazing.
sorry. I should add that I am in Nova Scotia.
Hi just got back from our favorite sand dollar cove…in the beautiful northwest puget sound area…it used to be that we would go betting who would find the largest sand dollar now we go betting on who will find the smallest…well today we found sand dollars 1/2 of a millimeter maybe even smaller…it was amazing…
Funny I went my whole life never having found a single sand dollar and now that I found this cove your completely surrounded by them to the point where every step you take is planned as to not step on them..
For as far as the eye can see..what a magical place ,,,,, and it’s minutes away from where I live…
Hi Jessi, Sounds amazing! You are lucky to live close to such a beautiful place.
Yesterday 7/30/16 I was on Sanibel Island Florida & found starfish & hundreds of brownish sand dollars on a sand reef about 20 yards off shore. Up north we call reefs sandbars. Anyway, I couldn’t see them because of murky water, but as I sat on the reef I could pick up several without moving. They were all alive with tiny cellia on its underside. I tried to avoid stepping on them & let them be. The only sand dollars I had previously seen were deceased. I hope this is helpful for your research. E mail me if I can be of further assistance.
Hi Ben, Apologies for the delayed response, I was out of town when you posted your comment. Thanks so much for the sand dollar information and thanks for being so careful around them, appreciate it!
We live in Ma.and swim at beaches in New England. The only place we have find Sand Dollars is at Hampton Beach, NH. They are anyehere from 1″ to 3″ in diameter. They are mostly a light grey or white, but lately we are finding a lot of black ones. I understand the black ones are still alive and shoukd not be picked, but do the lighter colors mean they are dead?
Hi Linda, Apologies for the delayed response, I was out of town when you posted your comment. Usually any color besides white means it’s a live sand dollar. That said, there are living white sand dollars so you really can’t just go by color. You have to get really close to the sand dollar and take a good look, do you see any velvety texture? A live sand dollar has a skin over the shell with small hairs called cilia, these are things you can definitely see if you get close enough. But as I’ve said in other comments, when it doubt leave it. You may want to contact one of the local Fish and Game Departments or Fish and Wildlife Departments (the names vary in each state), they might be able to tell you the color of the sand dollars in your area. I hope that helps!
Hi, all. I tried to read everything here thoroughly before posting. Forgive me if this is a repeat question. This morning I discovered a spot where, at low tide when it’s veryveryvery early, before the birds and the beachcombers show up, you can find tons of sand dollars, both living and dead, in the shallow water and also, surprisingly high up on the sand; almost to the dry sand! I didn’t know any better about the live ones and, delighted by their colors, brought home a handful to give as gifts. Now that I understand the difference, I won’t make that mistake again, poor things. Meanwhile, my house smells like a bait shop! Aside from burying them, how do I deal with the dead tissue (without bleaching them- I like the way they look.) I soaked them in water and scrubbed off the spines and that helped a little but the smell is persistent even in their absence. I have them drying outside now but I may end up swapping places with them and let them keep the house.
My other question is about the travelers. The birds are drawn to this spot because they know it means a feast. Should I give the ones that have wandered onto the beach a ride back to the water or should I just let nature take its course? Where do they think they’re going? Do they crawl away from the water because it’s time for them to die or are they just really bad with directions?
Hi Kerry, Apologies for the delayed response, I was out of town when you posted your comment. As far as how to preserve sand dollars, that is beyond my range of expertise. But thanks for taking the time to learn more and understand what to do the next time you’re at the beach.
As far as what to do when you find live sand dollars further up on the beach, I think it’s fine to leave them and let nature take it’s course. In addition, some ocean animals have adapted to living along the shore and are fine to be out of water until the next high tide comes along and takes them back to the ocean. I’m not sure if this is the case with the sand dollar species you’re seeing, but it’s definitely a possibility. Also, sand dollars aren’t the fastest movers, so I’m guessing the ones you see further up the beach had some help from the ocean and then ended up staying as the tide receded. If you live really close you could start your own citizen science project. It would be fun to visit the same spot at high tide and low tide and compare what you see. If there is a marine biologist in your area, they may have some tips for doing this.
In Florida it is unlawful to take live shells.
In fact, it is unlawful in most places.
Even if one is careful to take only one or two so as not to deplete the population, thousands of people doing the same will deplete the population:(
Hi Doris, Thank you so much for weighing in with that answer about what’s legal in Florida, really appreciate it. You’re right, even taking one or two live sand dollars here and there by hundreds of people will quickly deplete the population. Thanks for being an advocate for marine life!
Where did you get all those facts
I thought sand dollars were something made up by the creators of animal crossing (on the nintemdo) going to have so see if there are any native to the UK as I have never seen one.
i live by jeykell island georgia and visit that island a lot..mainly when the tides are low sense this one area is a major tourist place for beach goers in the summer. so i can put the live sandollars out of human way.. you would not believe how many of people will pic up the small live ones and take them as gifts.. most visitors do not know that if they are not white and are small that they are most likely alive….and i have seen people take like 20 or 30 of them at a time:(….i wish beaches like that would post signs so folks would know witch ones are ok to take….
Hi Lavada, I’m so bummed to learn this! I know there is a turtle rescue center on Jeykell Island. I wonder if their staff might know who could help post a sign about the sand dollars? It’s such a bummer that people take live sand dollars. Thanks for doing what you can to help protect them!!
I found a tiny sand dollar, the size of a dime today in the Gulf of Mexico, Destin, FL.
Anyone know when they reach their mature size?
Please do not collect these guys! What a horrible death to be minding your own business, living your life and then dying slowly out of the ocean. My family and I saw hundreds of them recently this winter in Florida. I was worried to think what would happen to them once the tourists started coming in and stepping on them all. I’ve lived my whole life in Florida and saw one once in Destin then saw this many all in one visit near St. Augustine! Crazy! It lead me to research them and found this website. I wondered if they were spawning or what the reason for there to be this many all in one location. Please leave these poor things where they belong.
Wow! That’s cool!! I think that they live in North Carolina because I found lots of them at a sandbar. Can u make one for dolphins?😃😁😊😍😝😋🐬🐬🐬
Thank you for this wealth of information. I frequent Bodega Bay Ca. Often find sand dallars but didn’t know much about them except that they are beautiful. Thanks again
I snorkel for sand dollars. I give them people with the Legend of the Sand Dollar poems. They have been very plentiful this year in Panama City Beach this Spring Summer 2016. What is the best way to not destroy the population and still retrieve some to give for presents. Some of the ones I picked out were about 4 inchES in diameter. How old are the sand dollars that are smaller than dimes. The species in Northwest Florida have been the same since 1978 when I snorkeedl for them as a child in Fort Wallton Beach. Is there a certain size that the sand dollars are so old that they do not reproduce anymore. I usually pick a few up at each community to not destroy the whole family or colony. take care God Bless David
Hi David, Great question! Based on everything I’ve read, it’s always advised to avoid collecting live animals for their shells. Life in the ocean is too precious. I’m not familiar with the average age of a sand dollar in association to their size. If you can track down a marine biologist that studies sand dollars in Florida, that’s probably your best bet. Also, I would contact the Florida Department of Fish and Wildlife to find out what the the rules and regulations are for taking sand dollars. They also may have a good sense of the health of the population.