Spiders
- Date Submitted: 01/28/2010 06:29 AM
- Flesch-Kincaid Score: 69.9
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Spiders can be found in all environments throughout the entire
world, except in the air and sea. (Biology of Spiders, R.Foelix) These
invertebrates of the order Aranea are one of the several groups of the
Class Arachnida, with about thirty four thousand species. They range in
body size from only a few millimeters in length to almost five inches.
All are carniverous and have four pair of walking legs, one pair of
pedipalps, and one pair of chelicerae. (Spiders, W.Shear) Each
chelicerae consists of a base and a fang. The fang folds up inside of a
groove in the base until needed when attacking food, then moves out to
bite and releases venom from a tiny opening at its end as it penetrates
the prey. (Biology Of Spiders, R.Foelix) They are also used to “chew”,
getting digestive juices inside the body of the prey then squeezing out
the liquid lunch. The pedipalps are mainly used to catch and rotate the
prey while the chelicerae inject it with poison to tear down the tissue.
Later the bases of the pedipalps are used as chewing parts. (The Spider
Book, J.Comstock) But in males, these palps are used to transfer sperm
into the female. These twleve appendages are attached to a dorsal and a
ventral plate, the carapace and sternum which cover the entire prosoma
and provide attachment points.
The bodies of spiders consist of two parts, an anterior part
called the prosoma and a posterior portion called the opisthsoma. These
two portions are held together by a narrow stalk called the pedicel.
This narrow junction allows for the spider to be very limber and acts
somewhat as a hinge between the prosoma and opisthosoma. So as a spider
moves foward creating a web, it can continue in a straight line throwing
its webbing in the direction it chooses. This is how spiders create
their...
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