Fun Facts: Secret Lives of Spiders

Arachnophobia – the fear of spiders – is one of the most common phobias in North America. But look a little closer, and you just might find spiders to be more fascinating than fearsome.

Photo by Doris May

Photo by Doris May

Spiders are not insects. Insects have 6 legs, antennae and 3 main body parts. Spiders have 8 legs, no antennae, and two main body parts (cephalothorax and abdomen).

Spiders are part of the Arachnid family. In Greek mythology, a girl named Arachne spun silk so well that the goddess Athena became jealous and turned her into a spider. The word spider comes from the Old English word “spithra” which means “spinner.” 

What has no teeth, blue blood and can run up walls?

Photo by Karthik Easvur

Photo by Karthik Easvur

  • Spiders inject digestive juices to liquefy the innards of their meal which they then suck up.
  • The feet of house spiders are covered in tiny hairs that can grip the surface of a wall. Garden spiders use claws instead to hold on to threads of silk.
  • Spider blood has no hemoglobin so it is blue instead of red.
  • Spiders use a muscle to pull their legs inward, and pump liquid into their legs to push them out.
  • A spider has no bones. Its body is protected by an exoskeleton which the spider sheds and re-grows throughout its life.
  • Most female spiders are bigger than male spiders.
  • Most spiders have 8 eyes, but are very near sighted. Tiny hairs on their legs help them to hear and smell. 

Impressive numbers

  • Found on every continent except Antarctica, there are currently 38,000 - 40,000 known species of spiders.
  • An estimated 1 million spiders live in one acre of land – perhaps up to 3 million in the tropics.
Goliath Spider by Snakecollector

Goliath Spider by Snakecollector

  • Spiders eat more insects than birds and bats combined.
  • The Goliath Spider (Theraphosa blondi) can grow up to 11” wide and has fangs up to 1” long.
  • The world’s smallest spider is the Patu marplesi. 10 of them could fit on the end of a pencil.
  • Wolf spiders can run at speeds of up to 2 feet per second.
  • Jumping spiders leap up to 40 times their own body length. The equivalent distance for human beings is 230 feet!

The adaptable spider

Raft spider by Ian Kirk

Raft spider by Ian Kirk

Not all spiders spin webs. A water spider uses it’s silk to construct a house underwater. The bolas spider swings a “fishing line” of silk to catch moths; other species make nets to capture their prey.

Of course, spiders can be food too. The bird-dropping spider looks like bird poo which prevents birds from eating it. Some spiders look like ants – a disguise they employ to escape predators. New World tarantulas fling off tiny hairs from their abdomen, which embed in a predator’s skin and eyes, giving the spider a chance to escape. A frightened wheel spider simply tucks in its legs and rolls away across the sand.

Scary spiders

Black Widow by Shenrich91

Black Widow by Shenrich91

Long ago, when an illness swept through Taranto, Italy, people believed it was caused by the bite of a wolf spider called a tarantula. This harmless spider became so well known that when Europeans settled in the New World, they called any large, hairy spider they came across a tarantula.

Although some species are large enough to kill and eat lizards, snakes, mice and frogs, most tarantulas pose no threat to humans.

Spiders don’t feed on human blood and won’t bite a human unless they feel frightened or surprised. The black widow spider and the brown recluse are the only spiders in North America whose bite can be serious. The venom of the female black widow is 15 times more powerful than that of a rattlesnake, so be cautious if you see a spider with the telltale red hourglass under its abdomen.

Family life

Female spiders lay up to 30,000 eggs at a time. The wolf spider is unusual in that it stays with her babies afterwards, carrying them on her back.

Photo by Circumjacence

Photo by Circumjacence

After mating only once, a female black widow spider can produce eggs for the rest of her life. They don’t always eat their partners, but the red widow’s mate will keep placing himself in her mandibles until she consumes him. Other male spiders settle for wooing a female with presents of dead flies.

Most spiders are solitary, but some species build large communal webs. Colonies can include thousands of individuals who work together to capture prey and share the harvest with one another. In India, these webs may cover trees for several miles.

The best spider mom in the world, Charlotte’s Web’s Charlotte A. Cavatica, is named after a common orb weaver, Araneus cavaticus.

We’ll discuss spider webs in another blog. In the meantime, if you’d like to learn more about spiders, try these sites:

By Louise Dorner, EALT Volunteer