Limnodrilus
hoffmeisteri is one of many species of aquatic
worms, also called "oligochaetes." Aquatic worms are close
relatives of earthworms, but they live in water instead of
the ground. Aquatic worms can be found anywhere there is
fresh water, including lakes, ponds, marshes,
and streams. They prefer shallow water.
Limnodrilus
hoffmeisteri grows up to five centimeters long, and its
body is about one millimeter wide. They have reddish bodies,
which are split into segments. Just like earthworms, the
ends of their bodies are pointed; but the body wall of these
worms is so thin, you can see through it to the animal's
organs. Though you might not normally notice them, these
aquatic worms are probably the most common animal in the
water!
Cluster of
Limnodrilus hoffmeisteri
Environmental Cleanup
& Restoration: CASE STUDY Foundry Cove in the Hudson
River, New York
Aquatic worms crawl around on top
of, or inside, the mud at the bottom. They eat the mud and any small
bits of plant or animal matter
they find. This worm often arranges itself head downward by building
a small tube in the mud and letting its butt stick out into the
water. Many aquatic worms can be found together; and their bodies,
sticking out of their tubes, wave back and forth with the currents of
the water.
Aquatic worms, like Limnodrilus
hoffmeisteri, are "bioturbators." This means they move the soil.
As the worm eats mud with its head down below, the dirt comes out the
back end of the worm. This soil-moving is very important to keep the
stream or lake healthy. Aquatic worms also break down pollutants
which settle to the bottom and poison the water.
Aquatic worms, just like
earthworms, are hermaphrodites.
This means there's not really a male or female. When aquatic worms
mate, each worm is then able to lay eggs. Aquatic worms lay eggs
inside small cocoons
in the mud, on rocks, or on plants. Eggs are usually laid in late
Summer or early Fall.
Juvenile aquatic worm from the
Tubificidae Family Tom
Bird, Biologica Environmental Services Ltd.
Aquatic worms have many
predators.
They are a favorite food for young fish, aquatic insects, leeches,
and crayfish. They are also eaten by tadpoles,
turtles, and ducks. These worms coil up when they feel
threatened.
Aquatic worms breathe through
their body walls. They can also regenerate,
or grow back, body segments which are damaged or lost.
Worms and cocoons are often
transported to new places when the mud they are in sticks to birds'
feet. Wading birds, like herons and egrets, drop them off in a new
lake or stream. Because of this, many species, such as Limnodrilus
hoffmeisteri, are found worldwide.
Aquatic worms are an important
food source for most young fish, many of which we eat when they grow
bigger. Aquatic worms also help break down pollutants in the mud at
the bottom of lakes, marshes, and streams. Aquatic worms sometimes
are hosts
for dangerous parasites,
such as The Big Red Worm.
