Pen Shells

I have always called these shells sea fans or fan shells, but they are called pen shells. Pen shells are actually a type of clam and they live in soft and sandy mud.
This is usually about the time of year you find tons of these on the beach, but, so far, I'm only finding the normal amount.
However, in all the years that I have seen pen shells on the beach, I've never seen one closed with the clam still inside. The first picture is a typical pen shell picture with rough spines along the shell. The inside of this shell is creamy with a beautiful iridescent purple. The second picture is of an intact pen shell with clam visible inside(click on the picture to enlarge and you can see the clam easily.)
Pen shells have a tiny foot which sends out "threads" to wrap around buried shells and rocks. The threads, called byssus, are so strong that it is said they were used in woven garments for Roman Emperors.
When alive, the ponted end of the shell is down in the sand and the "fan" end extends into the water above the sand, making barefoot walking hazardous around a bed of these shells.
The shell is thin when the clam is alive and the shell is closed by flexing, unlike other bivalves.
Two small creatures live inside the shell - a crab ad a shrimp. these feed off the excess that the pen shell pumps inside.

Pen Shell

Pen Shell

Sunday Afternoon Beach Walk

We have had rain for the past 3 days, but today the clouds disappeared and we had a sunny, beautiful day. It was so warm at the house, I expected the beach to have a lot of walkers and joggers. But the wind at Isle of Palms was very chilly and strong and there were few people on the beach this afternoon.
Most of the starfish have been swept out in the ocean, just a few left for the birds to feast on. The sea gulls are plentiful, but sluggish and not in a hurry to get away from this human.
The beach was not as full of neat shells today, but I did find another sea urchin test and then found this dead sea urchin with spines still attached. ( To get a closer look, just click on the picture.)
Although a sea urchin is an invertibrate, they have developed "bones." inside the body, around the mouth, is a stucture called Aristotle's lantern. It provides attachments for muscles thaat move 5 shiny white teeth to scrape rocks, as they eat the algae from the rocks.
If this sea urchin were turned over, you would see a hole about half the size of the test and the teeth would be around that hole.
Pen shells are starting to show up on the beach. Last February they were all over the sand, just like the starfish in January. It will be fun to see if that occurs again.

Clams

As I've said, this must be the season for many shells of the same kind to wash on shore. There are piles of these clams - I've always called them Razor Clams, but they may be Jack-Knife Clams. They are almost transparent. Clams are bivalves with both a front and back shell which hinge together. They have a foot which sticks out between the two shells and is used for burrowing into the sand and/or mud and for scooting sideways. They have 2 tube-like siphons on the opposite end which protrude. The siphons go to the surface and take in water full of planktons to "eat" and oxygen for its gills which are located by the foot.
These clams prefer to stay beneath the sand or mud, but can be uncovered by rough surf where starfish, snails, and crabs encounter a feast.
This picture is not large enough for you to see all of the other shells in and around these clams, but there are baby whelks, cockles, and coquina along with other various and sundry shells.

Sea Urchin Tests

Among all of the thousands of starfish on the beach are several Sea Urchin tests. The test is the shell-like portion of the urchin left when it dies. This one is, I think, a Purple Sea Urchin, even though the spines look black when you find one whole on the beach. The purple spine is a very dark purple. This dead starfish had it clasped tightly and I had to work to free it.
I'm assuming that the reason I found several of the tests is that the starfish had eaten them - a final meal, so to speak.
When alive, the urchin has neele-tipped spines covering the test.Most of the space inside the test of a sea urchin is devoted to storing unfertilized eggs. When the eggs are ripe, the female will shed hundreds of thousands of eggs. These are considered a delicacy in Japan and Greece, and are sold like ice cream in the Barbados.
The test is very, very fragile and so it is always fun to find an unbroken one.

Sand Dollars

Sand Dollars (the true name for these is "Keyhole Urchin") are fairly plentiful on the Isle of Palms, but are basically clustered in 2 places: around 52nd Ave in front of a hot pink house and further up towards the end of the island.. The ones at 52nd are typically already whitish and can usually only be found at low tide. If you're willing to walk in the water, you can often find 10-15 in one walk. The ones found further north, almost at the end of the island, tend to be alive. It is against the law to take a live sand dollar in SC, so when one is found, you need to turn it over and check to see if spines are moving. If not, it is dead and can be taken from the beach.

Sand Dollars are wedged/buried beneath the sand in beds which are parallel to the beach. The green-brown spines on the underneath are used for digging and are very short and the 5 petals on the top are hollow and used for breathing. The enemies of the Sand Dollar are starfish and flounder and so they burrow face first to escape these enemies and storms.

To get the white Sand Dollars that are found in stores, soak in 50% Clorox and 50% water and then set in the sun to finish the process.