Tag: mollusks

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.

Classifying Seashells

seashells
Marine mollusk variety

I am not in love with science.  I call my shells by their common names and pay little attention to the Latin names and don’t really care which “family” they belong to, but I realize that some people might.

So this is my attempt to explain the classification of seashells, beginning with the “Class”.

The variety of sea shells is amazingly huge.  I can’t imagine having to organize shells into groups and since the same types can look very different depending on their colors, size and age, but each type has been assigned a “class”.

The class is fairly simple to figure out since each has it’s obvious differences.

Gastropods : Snail type shells that curl around and are all in one piece (univalves).
Bivalves: Shells that come in two parts, such as a clams and oysters.
Cephalopods: Mollusks without shells (mostly – the nautilus is a cephalopod), such as the squid and octopus.
Tusk Shells or Scaphopods: tusk or tooth looking shells.
Chitons: Flattened and plated, very primitive looking.

Sand dollars, sea urchins and sea cucumbers are Echinoderms and not mollusks or seashells.

Worm Shell Cluster

worm shells
Worm Shell Cluster

I picked this up this little grouping of shells on a Florida beach somewhere.   A lot of my nature finds such as shells and pretty stones are used to decorate the dirt in my potted plants.  

It’s an unusual looking thing, with lots of ridges and holes.  Finding this bit of shell prompted me to learn more about the creatures who made it.

 

worm shell cluster
Many Worm Shells

Worm shells are made by snails, not worms, and are given the name only because their coiled shells resemble worms.  This group is called a variable worm shell and lives attached to rocks or other shells in colonies.  When they are living, the color is brown to purplish brown, but once the cluster is washed up on shore, the sun bleaches it.

Worm shell cluster tube openings
Openings in the cluster

My piece is small, only about 2.5 inches long, but large specimens, measuring 2 feet across, have been found living off the western Florida coast.