Zooplankton (zoo meaning animal, and plankton meaning free floating) are free floating animals and can range in size from 1/10 of a millimeter to a few centimeters. Although zooplankton are present in all of the Great Lakes, you may have never seen them before. They use small arms and legs to push themselves through the water, usually at night, to feed on algae in the upper waters of a lake.

Copepod (co-pe-pod)

There are many species of copepods, but all have antennae and a fan tail. The one in the picture is carrying a sac of eggs on her fan tail.

Mysis (my-sis)

One of the largest zooplankton, mysis can move very fast through the water when threatened. They are very good food for young fish.

Holopedium (holo-peed-e-um)

These creatures form a clear, gooey envelope around themselves, in which the females carry eggs. Holopedium can wash up on beaches in large amounts.

Rotifer (row-ti-fur)

Using small hair-like fibers, rotifers swirl water by their mouths to gather food for themselves. Once the food is caught, they close their mouths and digest it.