Alberta's Watchable Wildlife Invertebrates are found everywhere, from mountain tops to ocean bottoms, and from barren deserts to the darkest corners of caves. Invertebrates are animals without backbones. Insects are the most common invertebrates.
Invertebrates are the oldest known animals on earth.
Their fossil record goes back at least 600 million years. Insects, the most successful invertebrates, originated about 400 million years ago. Invertebrates occur in a tremendous variety of shapes and colors. These are adaptations to specific habitats. For example, burrowers, such as earthworms, usually have long tubular bodies and are darkly colored, similar to the soil in which they live.