Tag Archives: mollusks

The Crown Shell is a Perfect Home for Hermit Crabs

IMG_0607 hermit crbThe crown shell, sometimes called king’s crown, is recognizable by it’s pointy ridges and horizontal stripes.  When cleaned up, it’s a beautiful specimen.  When found in the wild, it may only be recognized by the points along the top of the swirls.

While visiting the intracoastal waterway (Indian River) backwater area this summer, I saw many crown shells in a variety of sizes.  They were often inhabited, not by the mollusk that made them, but by a hermit crab.

Many years ago my kids had hermit crabs as pets. This was mostly due to the fact that my daughter wanted to have one of every kind of animal on earth as her pet. We had to buy gravel to put in a small container for the crab and we had to provide empty seashells for it to move into when it grew.

Now I wonder how the hermit crabs we had as pets lived at all, since the ones I saw in the wild stay completely under water. And it’s salt water. They are walking all over the shallows and could be in deeper water too I suspect.  Apparently, after learning more about hermit crabs, there are different types, including my run in with the Giant Red Hermit Crab.

I would have come home with quite a nice collection of shells if not for the fact that hermit crabs had taken up residence in every one available!

hermit crab
Besides the beautiful striped crown shell, I found pear whelks and lightning whelks. The unique round shark’s eye was another I couldn’t collect.

Then, I finally found a crown shell with it’s owner inside. I took it out of the water for a moment to snap a photo and then I put him back. One day his shell will most likely be a hermit crab home.
crown shell and mollusk inside

The Spotted Flamingo Tongue Mollusk

Flamingo Tongue Snail in Profile
Image by laszlo-photo via Flickr

Sometimes a shell, living in the wild, will look very different than when it’s washed up empty on the beach. In the case of the Flamingo Tongue (Cyphoma gibbosum) snail, the coloring belongs to the animal while it’s alive.  The mantle, or fleshy, cape-like covering, is what you are looking at in this picture, and it contains the pretty roundish spots that are yellow-orange, outlined in a darker color.

It is not a large shell, measuring at most about 1.5 inches and you will probably only see one living if you are snorkeling or swimming since they live on sea fans and feed off of coral in shallow ocean water.

Although this looks like a beautiful shell to add to your collection, the shell itself, which is hidden from view by the mantle, is mostly white with a bit of a yellowish tint.  The outstanding characteristic of the shell is the ridge that you can see crossing the center of the shell.

Don’t be fooled into thinking you have found an amazing spotted seashell, if you see this little guy.  Collecting it will kill the animal and the shell will not have spots.  You will both lose.

Seashell Speak

Shells קונכיות
Image via Wikipedia

In my Florida life, a seashell was a seashell.  Some were prettier than others, some were larger and I just called them shells and never knew they were actually mollusks.  In fact, when I found a nice shell, I never gave much thought to what had once lived inside.

Now I have learned to speak seashell. At least to the degree that I know the difference between a gastropod and a bivalve and that animals in the phylum mollusca inhabit most every area of the earth, although I write about the marine mollusks, the ocean-dwelling ones. (In England mollusk is spelled “mollusc”.)

Mollusks are invertebrate animals and I am mostly interested in the ones that live inside their shell homes, but some mollusks don’t have shells (squid, cuttlefish and octopus).  They consist of single shells that are all in one piece – gastropods or univalves, and shells that are hinged, or two pieces – bivalves.  They all live in ocean water or brackish water, which is less salty as it is combined with fresh water.

I mainly use the common names of the shells when describing them, but the scientific names are important and each shell will have two parts to it’s name and it is always italicized with the first part being capitalized and the second is not. I don’t know why, and forgive me if I sometimes don’t include the scientific name, but searching for information about a certain shell is easier when using it. That is when you will come across the more scientific sites – which this blog is not.

When reading the descriptions of a gastropod on a more scientific site, you will read about the spire (top part of the shell), whorl (the way it twists), aperture (opening), lips (edges of the opening), canal, and operculum which seals the “door” when the animal retreats inside it’s shell.  The bivalve descriptions could include describing the umbones, ligament and hinge teeth.  Most descriptions will include colors and characteristics unique to that shell and the inside color along with the size and where it can be found.

It is difficult to find a lot of information and good photos online, and if you really want to study seashells, I suggest buying a book about shells in the area you plan to be beachcombing.

Seashell Markings and Bore Holes

I have collected some shells and pieces of shells that are full of holes or have crazy lines etched in the top. Sometime a shell will have a perfect hole all the way through it, just as if it was meant to be hung on a wire to make a pretty necklace. I never knew what caused these phenomenons until I read about “Shell Wars” in my new reference book, “Florida’s Living Beaches, A Guide For the Curious Beachcomber” by Blair and Don Witherington. In the mollusk section of the book they explain how some gastropods will bore holes through the shells of others to feed on them. In doing so, they leave a hole, or sometimes lots of holes as in the case of boring sponges that use acid to digest shells and actually leave them looking like a sponge – full of holes.
Black and White Cockle Shells Postcard postcard Tropical Treasures New Address Postcards postcard
You can see in my picture on the left that one of the cockle shells has a hole at the top and in the photo on the right there are plenty of examples of shells that have been changed into porous looking shapes and no longer resemble seashells.

When you find a beautiful shell on the beach, do you ever think about the creature that used to live inside? If you are like me, probably not. At least, I never did until I began to study seashells. I will never look at shell collecting the same way now that I can imagine the snail like animal moving about the ocean floor carrying his shell along, searching for food.  Sometimes that food is another mollusk.

The Frog Shell

Granulate Frog Shell - Bursa granularis

The frog shell is not extremely pretty as it tends to be covered in “limy deposits”.  The St. Thomas Frog Shell (Bursa thomae) got it’s name because it was first discovered in St. Thomas in the Virgin Islands. It’s a small shell, growing only to a little over an inch long.

Another frog shell – the California Frog Shell (Bursa californica) is commonly found in Baja California where it is frequently pulled up in crab and lobster traps. This species is larger and can be up to 5 inches in length.
Info taken from National Audubon Society’s Field Guide to Shells

See another photo of a frog shell – The Yellow Mouthed – here.