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Spiders are predatory invertebrate animals that
have two body segments, eight legs, no chewing mouth
parts and no wings. They are classified in the order
Araneae, one of several orders within the larger
class of arachnids, a group that also contains
scorpions, whip scorpions, mites, ticks, and opiliones
(harvestmen). The study of spiders is called
arachnology. All spiders produce silk, a thin, strong
protein strand extruded by the spider from spinnerets
most commonly found on the end of the abdomen. Many
species use it to trap insects in webs, although there
are also many species that hunt freely. Silk can be used
to aid in climbing, form smooth walls for burrows, build
egg sacs, wrap prey, and temporarily hold sperm, among
other applications.
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All spiders except those in the families Uloboridae and Holarchaeidae,
and in the suborder Mesothelae (together about 350 species) can inject
venom to protect themselves or to kill prey. Only about 200 species,
however, have bites that can pose health problems to humans. Many larger
species' bites may be quite painful, but will not produce lasting health
concerns. Spiders are found all over the world, from the tropics to
the Arctic, living underwater in silken domes they supply with air, and
on the tops of mountains. In 1973, Skylab 3 took two spiders into space
to test their web-spinning capabilities in zero gravity. |
Fire Ant bodies, like all insects' bodies, are
broken up into three sections: the head, the thorax, and
the abdomen, with three pairs of legs and a pair of
antennae. Fire ants can be distinguished from other ants
by their copper brown head and body with a darker
abdomen. The worker ants are blackish to reddish, and
their size varies from 2mm to 6 mm (0.12 in to 0.24 in).
These different sizes of the ants can all exist in the
same nest. A typical fire ant colony produces large
mounds in open areas, and feeds mostly on young plants,
seeds, and sometimes crickets. Fire ants often attack
small animals and can kill them. Unlike many other ants,
which bite and then spray acid on the wound, fire ants
only bite to get a grip and then sting (from the
abdomen) and inject a toxic
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alkaloid venom called Solenopsin, a compound from the class of
piperidines. For humans, this is a painful sting, a sensation similar to
what one feels when burned by fire — hence the name fire ant — and the
aftereffects of the sting can be deadly to sensitive individuals.
Although fire ants do not typically seek out and attack the face, they
are as likely to attack an exposed and vulnerable face as any other body
part. The venom is both insecticidal and antibiotic. Researchers have
proposed that nurse workers will spray their brood to protect them from
microorganisms. Fire ants nest in the soil, often near moist areas,
such as river banks, pond edges, watered lawns and highway edges.
Usually the nest will not be visible as it will be built under objects
such as timber, logs, rocks, pavers, bricks, etc. If there is no cover
for nesting, dome-shaped mounds will be constructed, but this is usually
only found in open spaces such as fields, parks and lawns. These mounds
can reach heights of 40 cm (15.7 in).
Colonies are founded by small groups of queens or single queens. Even
if only one queen survives, within a month or so the colony can expand
to thousands of individuals. Some colonies may be polygynous (having
multiple queens per nest) |
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