Physical Description
The earthworm is shaped exactly like any other worm, long, thin, and mostly
cylindrical. The bottom of the earthworm is rounded upwards and this is
where setae are located. The earthworm's body is segmented and has a mouth
covered by the prostomium, clitellum area (located one third of the way
down the worm, at the front end), and an anus. The skin of the earthworm
consists of a thin membrane through which the worm can breathe.
Roles of Features
Setae- soft, bristle-like hairs
Prostomium- a fleshy "lip" that covers the mouth
Clitellum- a band area that houses and protects the reproductive organs
Anus- opening for waste removal
Senses
The five senses are sight, taste, touch, hearing, and scent. The earthworm
can not see but can sense light with its front end, nor can it touch, but
it can feel when something touches it. When the earthworm is touched, it
moves itself away from the touch. It can not taste, hear, or smell.
Locomotion
The earthworm has two sets of muscles. Under its skin is a thin layer of
circular muscles running around the worm's body. Under these muscles is
a thicker layer of longitudinal muscles, running from end to end of the
worm's body. The circular muscles contract, making the earthworm longer
and thinner. When the longitudinal muscles contract the worm becomes shorter
and fatter.
Every segment on the earthworm's body has its own set of circular and longitudinal
muscles, along with four pairs of setae. The earthworm can stretch out
one part of its body while contracting the other. The alternate stretching
and contracting is how the earthworm moves.
Gathering Food
The earthworm eats its way through the soil as it moves along. This is
how the earthworm gets its food.
Survival
The earthworm must maintain a certain balance of moisture in its skin or
else it will dry out and die. After rain, earthworms often come to the
surface to avoid drowning.