Centipedes and millipedes are somewhat similar
organisms. Together, they make up approximately
twelve thousand species of long, flattened,
segmented animals, grouped among the
Myriapods. A major difference between centipedes
and millipedes is diet. Centipedes are carnivores,
living on other animals, and millipedes are
herbivores, living on dead plant matter. Millipedes
have cylindrical bodies, while centipedes
are wormlike.
Whena centipede or millipede runs, it picks up
each leg, one after the other. However, it only
moves the legs on one body side at a time. The result
is that legs move in rhythmic waves along
the body. Millipedes are much slower than centipedes.
Physical Characteristics of Centipedes
Centipedes belong to the class Chilopoda of the
phylum Arthropoda, which includes insects,
myriapods, crustaceans, and spiders. Centipedes
resemble worms. Their heads contain paired,
jointed, sensory antennae; brains, connected to
ganglia; compound eyes, simple eyes, or no eyes
at all. Centipedes also have two pairs of jaws. The
first pair are toothed mandibles and the second
pair, the underjaws, have palps.
A centipede body is divided into between
twelve and one hundred segments, each having
two legs, so the name "centipede", which means
"hundred-footed", is appropriate. The first pair of
legs, in the segment behind the head, holds poison
claws that are used to fight or kill prey. These
claws are full of a venom made in the head. Each
of the paired legs in all segments but the last one
are shorter, of similar length, and clawed. Those in
the last segment are longer than the others.Athin,
tail-like cercus projects from a centipede's rear.
Centipedes breathe through air tubes (tracheas)
on the sides of their bodies.
The Lives of Centipedes
Centipedes are carnivores that eat worms and insects,
which they poison. Nocturnal, they hide under
stones, logs, or ground litter during the day.
Some species bear live young, but most lay eggs.
Small centipedes of temperate climates (such as
the United States) are harmless to humans. Larger,
tropical centipedes are much more dangerous, as
exemplified by the families Scolopendridae, and
Geophilidae.
The reproductive cycle of centipedes often begins
in spring or fall, when a male places his semen
on the ground. In the spring, a female puts
the semen inside her body, immediately using it to
fertilize her eggs. If the female takes in the semen
in the fall, she may carry the semen for months before
fertilization occurs. After fertilization, females
lays their eggs, which hatch in two to four
weeks. Newborns have smaller numbers of segments
and legs than adults. They grow by molting.
After each molt, new body segments and legs
are produced. Mother centipedes tend their
young until they can hunt. Centipedes mate at
two to three years old and may live for six to ten
years.
Centipedes Large and Small
Scutigeridae have compound eyes, long antennae,
and fifteen pairs of long legs. Found in Europe
and the United States is a two-inch species
with a brown, striped body, the common house
centipede. Lithobiidae, stone centipedes, are also
short-bodied. They and scutigerids are the fastest
centipedes. Stone centipedes have simple eyes,
the same number of legs as scutigerids, and antennae
about 35 percent the length of their bodies.
Neither family delivers stings harmful to humans.
Scolopendridae have over twenty pairs of legs,
short antennae, and simple eyes or none at all.
These slow-moving, tropical centipedes are the
largest species, reaching lengths of one foot. The
fourth family, Geophilidae, known as soil centipedes,
are also slow moving. They have up to 350
legs, short feelers and no eyes. They burrow in the
ground. Scolopendrids and geophilids deliver
bites harmful to humans.
Millipedes
Millpedes are arthropods of the class Diplopoda
and occur worldwide, except for polar regions.
They are 0.1 to 12 inches long. The largest American
species, the four-inch, red and black Narceus
americanus, lives in southern forests.
Millipede heads are round and hold a pair of
short antennae, two simple eyes (or no eyes),
and mandibles. "Millipede" means "thousandfooted" but none have over five hundred legs. The
legs arise from the characteristic feature of diplopods,
9 to over 110 diplosomites. These double
trunk segments form by the fusion of two body
segments. Each diplosomite holds two pairs of
legs, except for the legless head segments and the
next three segments, each with one pair of legs.
Every four-legged diplosomite contains two pairs
of ganglia and two pairs of heart arteries. Millipedes
grow in length and diplosomite number by
molting. They live one to seven years and reproduce
by laying eggs.
Millipedes are covered with thick, calcified
chitin back plates. Their protective strategy, when
threatened, is to curl into a ball with their head inside
and excrete a smelly, toxic liquid from "stink
glands." This liquid kills or repels predators.
Millipedes inhabit dark, damp places and eat decaying-
or in some cases live-plants. Their actions
damage some crops but, more often, enrich
the soil.
Classification:
Kingdom: Animalia
Subkingdom: Bilateria
Phylum: Arthropoda
Subphylum: Uniramia
Class: Chilopoda (Centipedes)
Families: Geophilidae (soil centipedes), Lithobiidae
(stone centipedes), Scolopendridae
(tropical centipedes), Scutigeridae (house centipedes)
Geographical location: Worldwide, in temperate,
warm, or tropical regions
Habitat: Under stones, logs, leaves, other ground
litter; in human habitations
Gestational period: Eggs hatch in two to four
weeks
Life span: Six to ten years
Special anatomy: Sensory antennae; compound
eyes; toothed jaws and underjaws; segments,
each with two pairs of legs; poison claws;
cercus; air tubes
Copyright © 2014 Animalia Life | All rights reserved