Ninety-seven percent of all animals on our planet lack a backbone and are called invertebrates. They are all considered ectotherms,or “cold-blooded” because they cannot regulate their body temperature.
Invertebrates include many diverse groups such as the annelids (leaches and worms), arthropods (crabs, insects and spiders), cnidarians (sea anemones, corals and jellyfish), echinoderms (sea stars, sea cucumbers, and urchins), mollusks (clams, squid, octopus and snails), and porifera (sponges), just to name a few.
Types
Invertebrates
