Human impact on the environment or anthropogenic impact on the environment includes impacts on biophysical environments, biodiversity, and other resources. The term anthropogenic designates an effect or object resulting from human activity.
Animals can be divided broadly into vertebrates and invertebrates. Vertebrates have a backbone or spine (vertebral column), and amount to less than five percent of all described animal species. They include fish, amphibians, reptiles, birds and mammals. The remaining animals are the invertebrates, which lack a backbone. These include molluscs (clams, oysters, octopuses, squid, snails); arthropods (millipedes, centipedes, insects, spiders, scorpions, crabs, lobsters, shrimp); annelids (earthworms, leeches), cnidarians (jellyfish, sea anemones, corals), and sponges.
Vertebrates are backboned animals. The group includes amphibians like the spotted salamander, as well as mammals, birds and reptiles. The rarity of vertebrate endosymbiosis, as the cell-within-a-cell association is called, has been thought to be the result of the animals' stringently xenophobic immune systems.