copepod - minute marine or fresh-water crustaceans usually having six pairs of limbs on the thorax; some abundant in plankton and others parasitic on fishplankton - the aggregate of small plant and animal organisms that float or drift in great numbers in fresh or salt water crustacean - any mainly aquatic arthropod usually having a segmented body and chitinous exoskeleton britt, brit - minute crustaceans forming food for right whales water flea, cyclops - minute free-swimming freshwater copepod having a large median eye and pear-shaped body and long antennae used in swimming; important in some food chains and as intermediate hosts of parasitic worms that affect man e.g. Guinea worms |