Spiders Spiders

Scientific Classification

Common Name
101 families
Genus Species
40,000 species (approximation)

Fast Facts

Two body parts and eight walking legs; head and thorax are combined into one body segment (cephalothorax) and a second body segment (abdomen); leg has seven segments, tip of the legs of many spiders are two tiny claws; hard body shell (exoskeleton); no antennae, but has two appendages near their mouths that are often confused with insect antennae (pedipalps) to manipulate prey
Range in length from less than 1 mm (.04 in.) to more than 100 mm (4 in.)
Mainly insects and other arachnids; larger spiders eat small vertebrates, such as birds, snakes, and mammals
Sexual Maturity
Varies between species
Life Span
Varies; some large tarantulas have been known to live 20 years
Range from tundra to tropical lowland forests
Global: Unknown
IUCN: No data
CITES: Some species protected
USFWS: Some species protected

Fun Facts

  1. Although insects and spiders belong to the same taxonomic phylum, Arthropoda, they look very different from one another. These physical differences are what separate them in to two classes: Insecta and Arachnida.
  2. Though spiders have simple eyes, they usually are not well developed. Instead, spiders use vibrations, which they can sense on the surface of their web. The tiny bristles distributed all over a spider's body surface, are actually sensitive tactile receptors. These bristles are sensitive to a variety of stimuli including touch, vibration, and airflow.
  3. There are approximately 40,000 known species of spiders, which may be only one third of the actual number of spider species living on the planet.
  4. Spiders are arthropods, so their skeletal system of their body is the outermost layer. The hard exoskeleton helps the spider maintain moisture and not dry out. The bristles are not hair, but actually part of their exoskeleton.
  5. The word spider is from an Old English verb spinnan, meaning "to spin." Web weavers use the tiny claws at the base of each leg, in addition to their notched hairs, to walk on their webs without sticking to them.
  6. Spiders digest their food outside their body. After the prey is captured, spiders release digestive enzymes from their intestinal tract and cover the insect. These enzymes break down the body, which allows the spider suck up the liquid prey.

Ecology and Conservation

Spiders are the most abundant and diverse of all terrestrial predators. Spiders not only help control insect populations (including those insects that cause human disease), but they are food for other species too. They are widespread, living in habitats that range from tundra to tropical lowland forests. Currently, the U.S. Fish and Wildlife Service only classify two species of spiders as endangered.


Comstock, John. 1980. The Spider Book. Ithaca: Cornell University Press.

de Vosjoli, Philippe. Arachnomania The General Care and Maintenance of Tarantulas and Scorpions. Lakeside, California: Advanced Vivarium Systems, 1991.

Levi, Herbert W., and Levi, Lorna R. Spiders and Their Kin. Racine, Wisconsin: Western Publishing Co., Inc., 1987.