More than 43,000 different species of Spiders are found in the World. Of these, only a small number are said to be dangerous, and less than 30 (less than 1-10th of 1 percent) have been responsible for Human Deaths.
Why are so few Spiders harmful to humans? Much of the reason may result from the size differences between People and Spiders. Spider venom is designed to work on Smaller Animals, but the venom of some Species can produce Skin Lesions in People or produce Allergic Reactions that result in fatalities.
It is important to understand, however, that “Death By Spider Bite” is very rare since Clinics, Poison Control Centers and Hospitals often have various species-Specific Antivenin (the Antitoxin) on hand to treat the bite.
1. Brown Recluse Spider (Loxosceles Reclusa)
The brown recluse spider is one of The Most Dangerous Spiders in the United States. Its venom destroys the walls of blood vessels near the site of the bite, sometimes causing a large skin ulcer. Research in 2013 revealed that a protein in the spider’s venom targets phospholipid molecules, which make up a good portion of cell membranes and transforms these molecules into simpler lipids. The wound that is produced may require several months to heal, or it may become infected, which could lead to the death of the victim. Deaths from brown recluse spider bites are rare.
2. Brazilian Wandering Spiders (Phoneutria Fera and P. Nigriventer)
These species are sometimes also referred to as banana spiders because they are frequently found on banana leaves. They have an aggressive defense posture, in which they raise their front legs straight up into the air. Phoneutria are poisonous to humans, and they are considered to be the deadliest of all the world’s spiders. Their venom is toxic to the nervous system, causing symptoms such as salivation, irregular heartbeat, and prolonged, painful erections (priapism) in men. Scientists are investigating the venom of P. nigriventer as a possible treatment for erectile dysfunction.
3. Yellow Sac Spider (Cheiracanthium Inclusum)
Yellow sac spiders are Clubionids, a family of spiders (order Araneida) that range in body length from 3 to 15 mm (about 0.12 to 0.6 inch) and build silken tubes under stones, in leaves, or in grass. Cheiracanthium inclusum, found throughout the United States, as well as in Mexico southward through South America, is venomous to humans and is often found indoors.
4. Wolf Spider (Family Lycosidae)
Wolf spiders belong to the family Lycosidae, a large and widespread group that is found throughout the world. They are named for their wolflike habit of chasing and pouncing upon prey. About 125 species occur in North America, whereas there are about 50 in Europe. Numerous species occur north of the Arctic Circle. Most are small to medium-sized. The largest has a body about 2.5 cm (1 inch) long and legs about the same length. Most wolf spiders are dark brown, and their hairy bodies are long and broad, with stout, long legs. They are noted for their running speed and commonly occur in grass or under stones, logs, or leaf litter, though they may invade human dwellings that harbor insects. Most species build silk-lined, tubular nests in the ground. Some conceal the entrance with rubbish, whereas others build a turretlike structure above it. A few species spin webs. Wolf spider eggs are contained in a gray silk sac attached to the female’s spinnerets, or silk-producing organs, so that she appears to be dragging a large ball. After hatching, the young spiders ride on the mother’s back for several days.
5. Black Widow Spider (Latrodectus Mactans)
The black widow is responsible for more than 2,500 visits to poison control centers every year in the U.S. It is one species that can be found from the United States and parts of Canada through Latin America and the West Indies. The most common member of Latrodectus in North America, it makes its home in a variety of settings, such as woodpiles, burrows, or among plants that serve as supports for its web.
The female is shiny black and usually has a reddish to yellow hourglass design on the underside of the spherical abdomen.
6. Brown Widow Spider (Latrodectus Geometricus)
The brown widow is thought to have evolved in Africa, but the first specimen described came from South America. It is classified as an invasive species elsewhere around the world. Brown widow populations have appeared in southern California, the Caribbean, the U.S. states of the Gulf Coast, as well as in Japan, South Africa and Madagascar, Australia, and Cyprus. The species makes its home in buildings, inside old tires, and under automobiles, as well as among shrubs and other vegetation.
7. Red Widow Spider (Latrodectus Bishopi)
The third widow spider on this list is the red widow, or red-legged widow. The spider’s appearance is distinguished from other widow spiders by its reddish cephalothorax and legs and its reddish-brown to black colored abdomen. Many red widows have a red mark on the underside of the abdomen, which may be either hourglass-shaped, triangle-shaped, or indistinct. The top of the abdomen is spotted red or orange, with each spot surrounded by a yellow or white outline. The legspan of an adult female is 1.5-2 inches, whereas the male is only about one-third of that size.
8. Redback Spider (Latrodectus Hasselti)
The redback is another cousin of the black widow L. mactans; however, this species is not as widespread. It is native to Australia, but it has spread to New Zealand, Belgium, and Japan through grape exports. (The spider often builds nests and webs on grape leaves and inside bunches.) The species is widespread throughout Australia, living in all of the continent’s varied environments, except for its hottest deserts and frigid mountaintops. The species is also found in urban areas, frequently making nests in human dwellings. The redback is identified by its prominent red stripe or hourglass-shaped mark on its black-colored back. This mark is more noticeable on female redbacks than on males.
9. Funnel-Web Spiders (Family Dipluridae)
This family of spiders in the order Araneida are named for their funnel-shaped webs, which open wide at the mouth of the tube. The spider sits in the narrow funnel waiting for prey to contact the web. When this happens, the spider rushes out and captures the insect prey at the funnel’s mouth. The most important genera are Evagrus, Brachythele, and Microhexura in North America, Trechona in South America, and the poisonous members of the Atrax genus in Australia.
