- Chilopoda
- (Centipedes)
Introduction
Centipedes are an amazing group of animals, taxonomically they
are most commonly considered to be part of the Myriapoda along
with the Millipedes (Diplopoda), Symphyla and Pauropoda. However
there is still much to be learned about the relatedness of all
these arthropod groups, not only to each other but also to the
Insecta and the more basal Onycophora. There are about 2 500
named species in the world.
All Centipedes have numerous body segments with one pair of legs
per segment, the number of leg bearing segments and hence pairs
of legs ranges from 15 to 177, but is always an odd number. The
legs on the first body segment are modified into venom bearing
fangs that the Centipedes use to hunt their food. The body segments
are flattened and some or all of the bear spiracles for breathing,
the actual number varies between orders. Centipedes generally
have a single claw at the end of each leg which they walk or
run on (i.e. they are digitigrade), except the fast moving Scutigera
have a multi-articulate foot with numerous hairs to help them
get a better grip on the ground (i.e. they are plantigrade).
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- Centipedes have know waxy waterproofing layer
on their cuticle, hence they tend to be limited to damp or moist
situations, and are generally found in leaf litter in woods and
forests or in rotting timber. Many species are cavenicolous (i.e.
live in caves) a number of species can be found along the sea
shore under damp seaweed and other detritus and several species
of the Geophilomorpha are completely marine, i.e. Hydroschendyla
submarina from Bermuda. Most Centipedes have short legs which
are good for pushing yourself through the soil or into the leaf
litter or rotten wood, however the Scutigeromorpha which have
long legs which are better for moving quickly.
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- All Centipedes are primarily nocturnal, or
below ground hunters and are shy of the light, some species of
Scutigeromorpha are seen actively at times in daylight as well.
All Centipedes are also primarily carnivorous, however some of
the Geophilomorpha will eat plant material as well and can sometimes
occur in such large numbers as to be considered a pest. The larger
Scolopendrids may take small vertebrates including Mammals, Birds
and Reptiles. Though some species are easily get in captivity,
their basic carnivorous lifestyle can lead to cannibalism if
many are kept together, Geophilids are notoriously difficult
to keep in captivity. Centipedes appear to suffer from relatively
few parasites with less than 7% having any parasite in one study,
the culprits mainly being Nematodes and Tachinid flies.
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- Breeding
Males spin a small web onto which they deposit a spermatophore
for the female to take up, sometimes there is a courtship dance,
sometimes the males just leave them for the females to find.
In temperate areas egg laying occurs in Spring and Summer but
in subtropical and tropical areas there appears to be little
seasonality to Centipede breeding.
The Lithobiomorpha, and Scutigeromorpha lay their eggs singly
in holes in the soil, the female fills the hole in on the egg
and leaves it. The young usually hatch with only 7 pairs of legs
and gain the rest in successive moults. Scutigera coleoptera
the American House Centipede hatches with only 4 pairs of legs
and in successive moults has 5,7,9,11,15,15,15 and 15 before
becoming a sexually mature adult. It takes about 3 years for
S. coleoptera to achieve adulthood, however, like Millipedes,
Centipedes are relatively long lived when compared to their insect
cousins, the European Lithobius forficatus can live for 5-6 years.
- Females of Geophilomorphapha and Scolopendromorpha
show far more parental care, the eggs 15 - 60 in number are laid
in a nest in the soil or in rotten wood, the female stays with
the eggs, guarding and licking them to protect them from fungi.
The female in some species stays with the young after they have
hatched, guarding them until they are ready to leave. If disturbed
the females tend to either abandon the eggs or young or to eat
them, abandoned eggs tend to fall prey to fungi rapidly, thus
breeding is difficult to study in these species.
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- The Class Chilopoda is divided into 5 orders.
In some taxonomic schemes it is part of the Subphyllum Myriapoda.
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- Geophilomorpha
These are long worm like species adapted to burrowing in the
soil. They have 31 to 177 pairs of legs, 14 segments in the antennae,
and a spiracle on every segment except the first and last. Some
species such as the North American Orya barbarica may reach 15
- 17 cm (6 - 7 inches) in length, however most species are smaller
such as the European Haplophilus subterraneus which is about
3 -5 cm (2 - 3 inches) long.
Scolopendromorpha
This is a large order of Centipedes all of have less than 24
pairs of legs and 17 - 30 antennal segments. This order contains
the genus Scolopendra which includes S. gigantea which can be
over 30 cm (12 inches) in length. Many of the larger Scolopendrids
are colourful and venomous, some of them dangerously so, and
care should be taken to avoid being bitten.
The terminal legs are often modified; in the African genus Alipes
are flattened and expanded and are used in stridulation, in the
S. American genus Newportia they are antennae like in form and
function and in the genus Theotops they bear an enlarged claw
and are used to hold onto prey. Some species will autotomise
(let fall off deliberately) some of their legs to distract potential
predators. The order as a whole is more frequent in the topics
than in temperate regions.
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- Craterostigmomorpha
There is only one genus (Craterostigma) in this order which only
occurs in Australia and which appears to represent a halfway
stage between the Scolopendrids and the Lithobids. They have
15 pairs of legs and only 7 sets of spiracles.
Lithobiomorpha
This a relatively successful group of medium sized to smallish
Centipedes found commonly in temperate as well as tropical areas.
They have 20 - 50 antennal segments, 15 pairs of legs and only
6 or 7 pairs of spiracles.
Scutigeromorpha
These are all fast moving species which have 15 pairs of long
legs and spiracles on the first 7 segments only. They are the
only group of Centipedes to have compound eyes, all the others
have either simple eyes or none at all. They are above ground
hunters and are therefore more likely to be seen in those countries
where they occur, there are none in the UK. Scutigera longicornis
from India at about 5 -7 cm (2 -3 inches) is one of the largest
species known. Like the Scolopendrids they can autotomise their
legs when under threat from predators, in some cases these legs
continue to stridulate (make a noise) thus distracting the predator
from the whole animal.
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- gordon@earthlife.net
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Bringing Insects to the World http://www.earthlife.net/insects/
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