After the Precambrian Era, such marine invertebrate animal as trilobites, achiopods, nautiloids, horn corals, honeycomb corals and twiglike bryozoans were abundant during the Palaeozoic Era. The Palaeozoic was also the era when fishes, amphibians and reptiles appeared.
Any of various invertebrate animals such as a sea anemone or sponge that attach to surfaces and superficially resemble plants.
Most of the fossils seen in Paleozoic rocks are invertebrate animals lacking backbones, such as corals, mollusks and trilobites.
Moles are carnivores feeding almost exclusively small invertebrate animals living underground such as earthworms and the larvae of beetles and flies.
There was a hierarchical system in neurobiology, and working in invertebrate animals was not looked upon favorably, except in a very special case: the squid giant axon.
