This classification system allows scientists to study plant ... and porifera (sponges and other invertebrate animals). Class: Each of the animal phyla divides into smaller groups. For example, the ...

I have a classification key to help me identify ... Vertebrates are animals with a backbone, like mammals and reptiles. Invertebrates are animals without a backbone, like crustaceans, molluscs ...

Nielsen’s knowledge broadened to all invertebrate animal groups and ... Nielsen learnt that animal classification is a work in progress, and this challenge motivated his later work.

In dealing with the vertebrate vascular system ... A Zoological Pocket-book or Synopsis of Animal Classification. By Emil Selenka J. R. A. Davis (London: C. Griffin and Co., 1890.) ...