Invertebrates are animals that do not have a backbone.
Invertebrates are cold-blooded; their body temperature depends on the temperature
of their environment.
Some major groups of invertebrates include:
Protozoans - Very primitive, simple animals like amoebas
Some of the Metazoa - Porifera (sponges), jellyfish,
corals, tapeworms, flukes, insects, arachnids, crustaceans, mollusks, echinoderms,