They are the most abundant plankton (organisms that "drift") and have a central role in the marine food chain. Copepods eat the smaller diatoms, which derive their energy from the sun. In turn copepods are the food for the larger plankton, the juvenile forms of the all the animals that live in and on the bottom of the ocean.

The two long appendages at the front of the animal provide most of the propulsion, although there are several pairs of smaller legs under the animal that are not visible in this image. There is one eye at the very front of the copepod.

This copepod was collected in a net (mesh size 0.1 mm) by skimming the surface of the water along a dock in Sausalito (a little town just North of San Francisco). The image was formed with a 4x objective on a cheap "toy" microscope. It was captured using an inexpensive video unit attached to my personal computer.