Mussels on the Kaw Lecture

This lecture was developed by Craig Thompson, Biologist EPA Region 7

You can access resources to accompany this lecture by clicking on the links:

Illustrations can be downloaded from the attachment section on the bottom of this page or from the Illustrations and Handouts page

Lecture notes

What is mussel?

A mussel is an animal with two shells that are held together by elastic ligaments. Inside the shell they have soft bodies with two pairs of gills, a single foot for moving short distances and muscles for keeping their shells tightly closed

Where do they live?

Mussels live buried in silt, sand, gravel and rock substrates in the bottom of streams, rivers and lakes. They need fresh, flowing water to survive.

Mussels vs. snails (show photographs of both animals)
Mussels have 2 shells, have no distinct head, and no tentacles or eyes
Snails have one shell, have a prominent head, and tentacles

Parts of a mussel shell (show photograph of mussel)

There are 4 parts of a mussel shell (show photograph of mussel)

Anterior -This is the part of the shell where the mussel extends its foot (bottom of shell and in front).
Posterior - This is the part of the shell where the mussel uses tube-like siphons to bring water in and out of the shell (on top of shell and at the rear)
Dorsal margin (top of shell – like dorsal fin of fish, dolphin)
Ventral margin (bottom of shell)

Periostracum outer layer of the shell (or the skin) (show mussel shells with the following skin)

Some mussels have skin that has:

small, round raised bumps – Pimpleback, Mapleleaf, Threehorn wartyback
wrinkles – Threeridge, Washboard
smooth – Pocketbook

Skin color can be Brown, Black, or Tan

Inside of a mussel shell (show examples)

Color - Purple, pink, white (inside color of shell called Mother of pearl)
Teeth – teeth or no teeth (teeth used to hold the 2 shells together)
Muscle scars – where the animal attaches itself to the shell

All mussels and clams are filter feeders (show photograph with tube-like siphons)

Tube-like siphons bring water in and out of the shell.
The mussel uses its foot to bury itself in place then sticks its tube-like siphons out of the shell to feed and breathe.
One of the tubular siphons brings in water and then the other siphon brings it out.
The water that comes into the shell is filtered for food. The food that is filtered is microscopic algae, bacteria and detritus.

And mussels rely on dissolved oxygen from the water to breathe. Mussels have 2 gills to obtain this oxygen to breathe.

Life history of mussels

Mussels are parasitic in the early stages of life. They rely on a fish to survive the first couple of weeks of their life.

Young mussel larvae are called glochidia. Young mussels become attached to a fish’s gills, skin or fins after being released from their mother.

The young mussel remains attached to the fish for 1-10 weeks and does little harm to the fish.

When the young mussel leaves the fish, it drops to the bottom of the stream, river and begins growing and developing into an adult.

Introduced mussel species

Asiatic clam (show examples)

Occurs in most streams, rivers and lakes throughout the state

Zebra mussel (show examples)

Started showing up in lakes in the state. Now populating El Dorado Lake and Walnut River in south central Kansas (near Wichita)

Both species are filter feeders. They do not use fish in their early life stages, but use the current to carry the young larvae downstream. Zebra mussels are able to attach themselves to solid objects like rocks.

Mussel Species List

Mussel Lecture Illustrations

Back to Mussel Lesson Plan