Spiders: True or False?
Spiders evolved more than 300 million years ago, long before dinosaurs walked the Earth.
- True. Those ancient spiders didn't build webs but sought the safety of burrows dug underground. There, they were shaded from the Sun and protected from predators.
There are as many species of mammals as there are spiders.
- False. While there are about 6,000 mammal species, scientists have identified over 43,000 spider species so far. There may be at least as many still out there to be discovered.
Every spider sheds its exoskeleton, the inflexible outer shell, several times during its life.
- True. Most stop molting once they reach maturity, though females from some relatively primitive families of spiders continue to do so throughout their lives.
Spiders have poor eyesight.
- True. Nearly all have eight simple eyes--consisting of one lens and a retina--arranged in different ways but, for the most part, don't see very well. In most cases, spiders use other senses, like touch and smell, to help capture prey.
All spiders make webs.
- False. Only about 50 percent of known spider species do. Others hunt their prey or burrow underground. One species, Argyroneta aquatica, lives underwater.
All spider silk is the same.
- False. Spiders make many different kinds of silk, each with a property--toughness, flexibility, stickiness--specific to the task it performs.
Spiders are important predators.
- True. By one estimate, the spiders on one acre of woodland alone consume more than 80 pounds (36 kg) of insects a year! Those insect populations would explode without predators.
Not all spiders have venom.
- True. Those in the group Uloboridae don't. Instead of subduing their prey with venom, they wrap it tightly with silk.
I'm very likely to be bitten by a spider.
- False. With a few exceptions, spiders are very shy. They almost always run away rather than bite. In addition, misdiagnosis of insect bites as spider bites is very common.
Spiders don't care for their offspring.
- False. Many spiders do. For instance, a female wolf spider may carry an egg sac containing her young for weeks. Once the spiderlings hatch, she hauls as many as 100 or more of them on her back for another week or so.
Like many animals, spiders are threatened by habitat destruction and introduced species.
- True. Despite these threats, spiders and other non-vertebrates can be overlooked in conservation planning, in part because they're so small.