http://www.ck12.org Chapter 14. Understanding Biodiversity: Animals: Invertebrates
Evolution
The spider has been evolving for at least 400 million years. Their ancestors were more crab-like in appearance.
The spider’s use of silk has also evolved with the changing plant and insect population as well. The silk may have
originally been used as a protective covering for eggs, but later utilized as a home and a tool for hunting by species
like the trapdoor spider.
Ecology
The trapdoor spider eats small insects and other smaller spiders. Female spiders will capture their prey and regurgi-
tate it to feed their spiderlings. Enemies of the trapdoor spider include certain kinds of spider wasps. The wasp will
sting the spider, inserting its eggs into the spider’s body. When the eggs hatch, the larvae will eat the spider alive.
In the fall, the male leaves its burrow to look for female spiders for mating. The female, however, never travels far
from her burrow, especially if she has an egg sack.
Anatomy and Physiology
Trapdoor spiders are a medium-sized spider. The spider has a bulky body and legs. They have large venom glands
that have been known to be harmful to humans. They also have special spines on their jaws called a rastellum that
help them dig their holes. As with many spiders, the female trapdoor spider is larger than the male and can lay up to
10,000,000,000 eggs at a time.
Behavior
The trapdoor spider is a solitary spider. It digs the hole that it hides in 6-7 inches deep into the side of a hill using
its fangs, and then lines the inside if it with silk. It makes the “trapdoor” part of the hole with saliva, dirt, and silk.
They have poor eyesight, so they rely on the vibrations that an insect causes when it walks by. It is non-aggressive
in general but will hold its ground when cornered.
References
- Stefoff, Rebecca. The Arachnid Class. New York: Marshall Cavendish Benchmark, 2009. Print.
- http://www.naturebytesvideo.com
- http//www.insectidentification.com
- Zabludoff, Marc. Spiders. New York: Marshall Cavendish Benchmark, 2004. Print.
Attribution
Authors
- Gaven Springer
- Orion Silva