Copepods: The fastest animal in the world!

Sham S. Misri

The Copepods are a tiny cousin of crabs and lobsters. The copepod is for its size the fastest animal on earth.

Copepods are tiny crustaceans, so they are cousins of crayfish and water fleas. They can be seen with naked eyes. There are many species of copepods that live in our freshwater ponds, marshes, and streams, including damp soil and ditches. They live near the surface or in shallow water with lots of plants.

They have ten legs, which they use for swimming. The abdomen is like a rudder and helps the copepod steer. Copepods eat other tiny plankton organisms, including: bacteria, protozoan’s, (amoeba, paramecium, euglena, etc.), tiny insect larvae (including mosquitoes), and other crustaceans. They will even eat other copepods! Copepods also eat tiny bits of plant and animal matter floating in the current.

A speeding copepod looks like it is being shot out of a canon! If a cheetah (the fastest animal on the land) and a copepod were the same size , a cheetah running at 70 miles per hour (mph) would compare to a copepod moving at 2000 mph. The most distinctive feature of copepod is its long, antennae which help the animal sense the vibrations from approaching food or enemies. A copepod in search of meal stretches out its antennae like radar, waiting for signals from the sea. If it senses danger, it slaps its antennae against its body and darts away. It can propel itself up to 500 times its body length in less than a second

Copepods, besides being fast, are so numerous, so common that they are called the “insects of the sea.” Chances are they are the most abundant animals in the ocean, possibly on earth, with an estimated population of one quintillion (count the zeros-1,000,000,000,000,000,000!). If all the copepods in the world were divided equally among the entire human population , there would be enough for every person on earth to have one billion copepods. What would we do with them all?

We would feed almost all the creatures in the ocean, of course. Copepods are the key animals in the ocean food web. They are the main food for many larger animals in the sea, including shrimp, baby cod, and sea birds and others. A whale can eat millions of copepods every day. There are nearly 12,000 different kinds of copepods swimming through the ocean and living in the deepest ocean trenches. Some burrow into the mud. Most are of the size of grain of rice, but some inch-long isopods , called “whale lice” even make their homes on whales, and others live in the mouths and gills of fish.

Female copepods are much larger than males. After mating, the females carry clusters of eggs, called "ovisacs." The eggs can hatch between 12 hours to 5 days.

Each tiny larva, swims away from its mother after it hatches. The larva will eat and grow, going through nearly 11 stages before it becomes an adult copepod. When it is born, the larva doesn't look at all like the adult; for instance, it doesn't have all its legs and is much smaller. With each new stage, the copepod gains legs, other body parts, and size. The entire life cycle can last from 1 week to 6 months, depending on the temperature and environment. If it gets too cold, the copepods will rest on the bottom and become inactive until the temperature rises.