|The black widow spider is not as dangerous
as its reputation implies. It has caused only 55 human deaths during a
217 year period. Black widow spiders are found throughout the warm parts
of the world. The most familiar species are in North America. They are
known for their powerful venom, which is deadly to prey but rarely fatal
to humans. In other countries, black widows may be known by different names,
such as hourglass, redback, jockey, or button spider.
Habits: The black widow spider lives in various types of wild habitat and cultivated farmland, but it is best known for populating human residences. It likes dark, secluded places, such as in cellars and sheds and underneath houses. This spider spins its messy web beneath floorboards or in piles of rubbish and wood. The black widow is a shy, solitary creature and will attack humans only when surprised or threatened. Its venom is called a neurotoxin – it attacks the nervous system, causes severe pain and muscle cramps, and makes breathing difficult. These symptoms, although unpleasant to humans, are rarely fatal.
The front part of the black widow’s body, called the cephalothorax, houses poison glands. Venom passes through ducts to the spider’s fangs, known as chelicerae. The black widow stabs its prey with its fangs to inject the venom, though its mouth is really adapted for sucking. Markings occur below or on top of the abdomen, depending on the species.
Breeding: Before seeking a mate, the male black widow spins a web and rubs a drop of semen (fluid that carries the sperm) on it. He then transfers the semen to reservoirs in his palps, which are limbs near his mouth that look like a pair of short legs. Then he finds a female and vibrates her web, signalling that he is ready to mate. During mating the male transfer the sperm from his palps to the female’s body. Only one mating is necessary, since the female stores the sperm and uses it for several months to fertilize five or six batches of eggs.
The female spins a silken cocoon and lays the eggs inside as she fertilizes them with sperm. Each cocoon contains 10 to 100 or more eggs. The eggs hatch into tiny, pale spiders that quickly become independent. Compared to his mate, the male black widow spider is much smaller. The female guards her cocoon of eggs, which is often tied to her web with silk.
Food and Hunting: The black widow spider eats flies, moths, and other flying insects, as well as ants and even some spiders. It spins a tangled, three dimensional web. The male black widow’s web is much smaller than the female’s. The spider waits for its prey while sitting on the web, with its feet touching the strands. An insect flying into the web quickly becomes entangled. The black widow detects the vibrations and runs out and binds the prey with sticky silk.
The spider injects venom and saliva that contains digestive fluids into the prey’s body, paralyzing it. Over the next hour or two, the saliva predigests (liquefies) the contents of the prey’s body. The black widow feeds by sucking out the predigested material. The prey is reduced to an empty shell, which the spider cuts away from the web and lets fall to the ground.
Black Widow and Man: The black widow spider has a reputation for being a killer, but few people actually die from its venom. This shy spider avoids humans rather than attacking them. In the United States from 1726 to 1943, there were 1,291 cases of black widow bites recorded; only 55 of those people died. Most of the victims were probably children, the sick, or the elderly, whose small size or weakened condition contributed to their deaths.
Features of the Black Widow Spider:
Did You Know: The myth that the female
black widow always eats the male after mating is untrue. Only when the
male becomes weak and near death after several matings does the female
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