cat-faced spider

About spiders

Spiders belong to a group of invertebrates called arachnids, all of which have eight legs.

There could be a thousand species of spiders in Alberta. They are found anywhere (even underwater) there are insects that can be used as food.


Most Alberta spiders are small, with a total leg span of less than 5 millimetres (less than a quarter of an inch), but some have a leg span of more than 50 millimetres (2 inches)

Eight-legged predators

All spiders are predators, and they play an important role in nature by keeping insect populations under control.

Spiders use a variety of ways to catch prey, including:

  • Fashioning webs from sticky threads to trap prey
  • Chasing prey
  • Ambushing prey

Spiders bite their victims and kill them with poison. They then suck out the blood. After the blood is sucked out, the spider injects enzymes that turn the insides of the victim to liquid, which the spider then sucks up. Spiders consume only liquids.

Reproduction and Growth
  • Some spiders lay only a few eggs, others lay several hundred.
  • Shortly after mating, the male dies, and is sometimes eaten by the female.
  • Many spider species take two or three years to mature.

Dangerous to people?

In Alberta, only the black widow spider is dangerous to people, its venom being quite potent. It is found in the grassland natural region in southeast Alberta and is reclusive and not aggressive.


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Updated: Apr 8, 2009