Spiders

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...