Scientists classify animals by their characteristics, the ways they are alike.

Let’s see how scientists classify spiders and insects:
1. Living things that move from place to place by themselves, and do not make their own food are called animals. Both spiders and insects are animals.
2. Some animals have backbones. They are called vertebrates. Some animals do not have backbones. They are called invertebrates. Invertebrates are cold-blooded; their body temperature depends on the temperature of where they are. Both spiders and insects are invertebrates. They are both cold-blooded. They do not have a backbone. They have an exoskeleton. They have a hard outside! Did you know that 97% of all animals are invertebrates?
3. Scientists call one group of invertebrates arthropods. They are the most numerous animals on Earth! Both spiders and insects are arthropods. They both have a segmented body and jointed legs.
4. Arthropods contain a few groups of animals. One is insects. Another group is called arachnids, and that contains all the spiders in the world! Some other arthropod groups are crustaceans (lobsters, crabs and shrimp), centipedes, and millipedes.
5. All spiders are arachnids, but not all arachnids are spiders! Some are scorpions, mites and ticks. Whew! This can get confusing!



Spiders and Insects are Different in Some Ways!!
Spiders
Insects
Two main body parts, the cephalothorax, which combines the head and thorax, and an abdomen
Three body parts, the head, thorax, and abdomen
Do not have antennas
Have antennas
Eight legs
Six legs
No wings
Most have wings
Most have eight eyes
Most have six eyes
Simple eyes
Compound eyes
Poor vision
Good vision
Slender waist
Thick waist
All carnivorous, eat meat
Some are not carnivorous and eat plants
37,000 known species
Over a million known species
Make silk
Do not make silk
All have venom
Some have venom
Adult spiders still grow
Adult insects do not grow
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Web Page Created By
Jill Dembsky
Updated 9/2007