Copepod

Macrocyclops albidus

Copyright, Max-Planck-Institut fur Limnologie

Copepods are tiny crustaceans, so they are cousins of crayfish and water fleas. You can see them with your eyes, but they don't get much bigger than 2 millimeters. There are many species of copepods that live in our freshwater ponds, marshes, and streams; all the pictures on this page are of the species Macrocyclops albidus. Macrocyclops albidus is one of our most common species.

Copepods live just about everywhere there is fresh water, including damp soil and ditches. Macrocyclops albidus lives near the surface or in shallow water with lots of plants, but they also sometimes hang out on the bottom.

Department of Evolutionary Ecology, Max Planck Society

Copyright, Dr. Ralf Wagner

Like their crustacean cousins, copepods have two main body parts: cephalothorax and abdomen. They have ten legs, which they use for swimming. The abdomen is like a rudder and helps the copepod steer.

Macrocyclops albidus and other copepods eat other tiny plankton organisms, including: bacteria, protozoans, (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. Sometimes they attack the fins of fry (baby fish) or other small fish. When there are large numbers of copepods, they can even kill fish.

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

Department of Evolutionary Ecology, Max Planck Society

Department of Evolutionary Ecology, Max Planck Society

Each tiny larva, called a "nauplius," swims away from its mother after it hatches. The naupilus will eat and grow, going through 11 stages before it becomes an adult copepod. When it is born, the nauplius 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 anywhere from 1 week to 6 months, depending on the temperature and environment.

Macrocyclops albidus, and other copepods, slow down when the weather gets cooler. If it gets too cold, the copepods will rest on the bottom and become inactive until the temperature goes back up.

Copepods can occur in huge numbers. Sometimes over 1,000 copepods have been found in one liter of water. Numbers peak in September and October.

Copyright, Dr. Ralf Wagner

Predators of copepods include other plankton eaters; such as fish, amphibians (tadpoles and newts), water fleas, rotifers, and aquatic insects.

Copepods can be hosts for parasites, including tapeworms and flukes, which later end up inside fish, frogs, birds, or other animals.

Copepods are frequently transported by birds to new places. When swimming or wading birds, like ducks or herons, leave the water, copepods and other small organisms stick to their feet. When a bird lands in a new pond or stream, the copepods have a new home.

Copepods often live inside crayfish burrows.

Relationships in Nature:

FOOD/PREY
PREDATORS
SHELTER
OTHER

Green Algae

Creek Chub

Greater Bladderwort

Crayfish SP

Amoeba

Eastern Mosquitofish

Long-leaf Pondweed

Great Blue Heron D

Euglena

Eastern Lamp Mussel

Common Duckweed

Mallard D

Paramecium

Rotifer

Lizard's Tail

Wood Duck D

Water Flea

Ebony Jewelwing

Common Cattail

Canada Goose D

Asian Tiger Mosquito

Green Darner

Common Reed

Copepod

Golden Shiner

Pickerelweed

Eastern Mosquitofish

Greater Bladderwort

Tussock Sedge

Creek Chub

Largemouth Bass

Buttonbush

Rotifer

Three-lined Salamander

Arrow Arum

Predatory Nematode

Southern Leopard Frog

Yellow Pond Lily

Brainworm Nematode

American Toad

Flatworm

Eastern Newt

Green Hydra

Spring Peeper

Northern Hog Sucker

Copepod

Flatworm

Green Hydra

American Eel

Fragile Forktail

Relationship to Humans:

Copepods help humans since they are an important food source for baby fish. The fish that people catch and eat can't grow big if they don't have copepods for meals when they are very young. Copepods eat tiny insect larvae, such as mosquitoes. Copepods are also studied by scientists to see how clean water is.

KINGDOM
Animal
PHYLUM
Arthropod
CLASS
CrustaceanIsopoda
ORDER
Cyclopoida
FAMILY
Cyclopidae
GENUS
Macrocyclops
SPECIES
Macrocyclops albidus

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