Chilopoda (ki-lop´o-da) (Gr. cheilos
margin, lip, + pous, podos,
centipedes, are land forms with somewhat
flattened bodies that may contain
from a few to 177 somites (Figure 20-1).
Each somite, except the one behind the
head and the last two in the body, bears
a pair of jointed legs. Appendages of
the first body segment are modified to
form poison claws.
A, A centipede, Scolopendra (class
Chilopoda) from the Amazon Basin, Peru.
Most segments have one pair
appendages each. First segment bears a
pair of poison claws, which in some
species can inflict serious
Centipedes are carnivorous. B, Head of
The head appendages are similar
to those of an insect. There are a pair
of antennae, a pair of mandibles, and
one or two pairs of maxillae. A pair of
eyes on the dorsal side of the head
consists of groups of ocelli.
The digestive system is a straight
tube into which salivary glands empty
at the anterior end. Two pairs of
malpighian tubules empty into the
hind part of the intestine. There is an
elongated heart with a pair of arteries
to each somite. The heart has a series
of ostia to provide for return of the
blood to the heart from the hemocoel.
Respiration is by means of a tracheal
system of branched air tubes that come
from a pair of spiracles in each somite.
The nervous system is typically arthropod,
and there is also a visceral nervous
Sexes are separate, with unpaired
gonads and paired ducts. Some centipedes
lay eggs and others are viviparous.
The young are similar in form to
Centipedes prefer moist places
such as under logs, bark, and stones.
They are very agile and are carnivorous
in their eating habits, living on
earthworms, cockroaches, and other
insects. They kill their prey with their
poison claws and then chew it with
their mandibles. Common house centipedes Scutigera
, shield, + gera
, bearing), which have 15 pairs of
legs, are often seen scurrying around
bathrooms and damp cellars, where
they catch insects. Most species of
centipedes are harmless to humans,
although many tropical centipedes,
some of which may reach a length of
30 cm, are dangerous.