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Spider Primer

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Scientists have identified more than 44,500 spider species so far (for comparison, there are about 6,000 mammal species). Before you head out to see the 16 species featured in Spiders Alive! curated by Norman Platnick, curator emeritus in the Division of Invertebrate Zoology here are some amazing arachnid facts.  

A rack holding hundreds of tiny vials containing spider specimens in collection at the Museum.
These vials of spiders preserved in alcohol are just a tiny sample of the collection at the Museum. In fact, with over a million spiders, the Museum has the largest research collection in the world.
© AMNH/R. Mickens

Spiders evolved more than 300 million years ago, long before dinosaurs walked the Earth. 

100,000-million-year old fossil of a spider embedded in limestone.
This is a rare 100-million-year-old fossil of a spider in limestone. Spiders do not preserve well in sediment because they have a relatively soft “shell” or exoskeleton. For every 1,000 or so insect fossils found, there’s only one spider.
© AMNH\D. Grimaldi

Nearly all spiders have eight simple eyes—consisting of one lens and a retina—arranged in different ways. But, for the most part, they don’t see very well. In most cases, spiders use other senses, like touch and smell, to help capture prey.

Goliath bird eater
Goliath bird eater (Theraphosa stirmi): One of the biggest spiders in the world, it preys on snakes, mice, and frogs but, despite the name, rarely birds.
©AMNH/R. Mickens

Only about 50 percent of known spider species make webs. Others hunt their prey or burrow underground and one species, Argyroneta aquatica, lives underwater.

Wolf spider (Hogna antelucana)
This active hunter searches for food on foot, aided by sharp vision and its ability to sense vibrations—like those of the beating wing on an insect or the patter of steps on the soil.
(c) AMNH/R. Mickens

Many spiders care for their offspring. 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.

Learn more in the exhibition, Spiders Alive! 

This story is adapted from an article in the Spring 2014 issue of Rotunda, the Member magazine.