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Facts About Seashells

The diagrams below depict the basic anatomy of univalve and bivalve sea shells. Univalves are shells made up of one single structure such as conchs, murex and volutes. Bivalves which include clams, scallops and oysters consist of two separate halves.

Basic anotomy of univalve sea shells.

1. Apex:  The tip or smallest point where the growth of the juvenile mollusk began.
2. Suture:  Where each completed spiral meets or connects.
3. Body whorl:  The last and largest spiral of which most of the animal resides.
4. Inner lip:  The inside edge of the opening.
5. Spire:  Whorls above the body whorl where the younger body of the mollusk previously inhabited.
6. Outer lip:  The outside edge of the opening.
7. Aperture:  The opening surrounded by the inner and outer lip.
8. Canal:  This houses the siphon, a soft tube of the animal used for feeding or expelling waste.

Basic anotomy of bivalve seashells.

1. Growth lines:  These lines characterize a transitory suspension in growth.
2. Left valve:  The entire left half of a bivalve. This is not determined simply by the position of the shell. The left valve of a clam can be identified as follows. Place the valve flat in front of you opening side down with the umbo pointing away. The lunule or indented side will be on the left.
3. Umbo:   (aka beak) The curved protrusions at the base of each valve representing the initial growth of the bivalve.
4. Right valve:  The entire right half of a bivalve. (opposite of left valve)
5. Lunule:  The oval or heart shaped indentation located in the front of the umbones or beaks.

We'll be adding more facts about seashells soon so visit us again to learn more.

Author: Amy Ferguson