In this class of insects the head and thorax are joined together in one mass, on which they have two pairs of jaws, and four pairs of legs.
Scorpions.—These spider-like animals have four pairs of legs and a pair of large pincers, as well as a small pair on the anterior half of the body; while the hinder portion consists of at first a broad region, followed by a narrower one, the whole terminated with a sting, with which a poison gland is connected. The animal strikes by bending the end of this tail over the back. Its sting is very painful, but rarely if ever is it fatal. Scorpions occur as far north as Nebraska, but are more common in the tropics. They bring forth living young and care for their brood for a while.
Spiders have jointed bodies and legs. The bodies are divided into two regions, the anterior of these bearing four pairs of legs and two smaller pairs of appendages. The most anterior of these are the poison claws. They have a poison gland in the base, while the end of the claw tapers to a point. The front of the head has from six to eight simple eyes. The hinder half of the body, the abdomen, is without appendages, save for two or three pairs of very small projections, the spinnerets. Each of these has numbers of openings at the tip, through which a fluid is forced at will. This hardens immediately it comes in contact with the air and furnishes the silk of which the spider’s web is woven. Fine as it is, this silk is really a cable, being made of numbers of finer threads, one for each opening in the spinnerets. They use the silk for making webs, for cocoons for the eggs, nests, and in some cases for parachutes for flying. Each species makes its own type of web.
Spiders breathe by means of sacks—so-called lungs—on the lower side of the abdomen.
Our common house spider is the same as that of Europe; the largest species we see is the one found occasionally in banana bunches.
The Tarantula has the greatest reputation from the unfounded belief that its bite causes madness which can be cured only by music. So far as is known there is only one species which can cause serious effects by biting man, and even these cases are not sufficiently authenticated.
The Bird Catching Spider is a gigantic spider native to Surinam and elsewhere. It preys upon insects and small birds, which it hunts for and pounces upon. It is about two inches long, very hairy, and almost black; its feet when spread out occupy a surface of nearly a foot in diameter.
Hunter-Spiders. A great many of this species construct no webs, but use their silk merely for lining their dwellings—which are commonly underground—or the construction of protective investments for the eggs. Such forms simply stalk their prey, seizing the victims, when near enough, by a sudden [232] spring. One such type is the tarantula spider described above.
Water Spiders are found in ponds and ditches in this country. They hunt down small crustaceans but do not construct a web. For the protection of the eggs a thimble-shaped nest is woven, moored by threads to stems or leaves, and smeared externally with liquid silk to make it watertight. The nest is filled with air brought down from the surface of the pond in successive bubbles adhering to the hairy body of the spider.