Invertebrate

Invertebrate is a term coined by Jean-Baptiste Lamarck to describe any animal without a spinal column. It therefore includes all animals except vertebrates (fish, reptiles, amphibians, birds and mammals).

Lamarck divided these animals into two groups, the Insecta and the Vermes, but now, they are classified into over 30 phyla, from simple organisms such as sponges and flatworms to complex animals such as arthropods and mollusks.

Since invertebrates include all animals except a certain group, invertebrates form a paraphyletic group, but, despite not forming a "natural group" (that is, monophyletic), "invertebrate" is still a widely used term. Invertebrates include 97% of all animal species.

Earthworm

Earthworms are segmented worms that dig through the soil by eating it, digesting it, and then excreting it. This provides air-holes so plants' roots can breathe and water can move into the soil. Their digestion of organic materials in soils makes nutrients more available to plants and neutralizes the soil pH.

Hissing Cockroach

From the island of Madagascar, these cockroaches can grow to 4" long. They produce a hissing noise by quickly contracting their exoskeleton, squeezing air though the spiricles in the side of their bodies. The noise can scare away potential predators like birds.

Chilean Rose-hair Tarantula

This is a large, hairy spider from Chile, South America. It feeds on insects and an occasional small vertebrate. Tarantulas hide during the day and hunt at night. Feared by many due to the exploitation by Hollywood, these spiders are much less venomous than a Black Widow or a Brown Recluse.

Land Hermit Crab	Emperor Scorpion