nonmammals

Nonmammals is an informal umbrella term for all animals that are not mammals. It encompasses a vast range of life, including vertebrates such as birds, reptiles, amphibians, and fishes, as well as invertebrates such as insects, arachnids, mollusks, crustaceans, echinoderms, and many others. Because it is not a formal taxonomic category, the term is mainly used for general description rather than precise classification. In contrast to mammals, nonmammalian vertebrates generally lack mammary glands and hair, and invertebrates lack a backbone altogether.

The diversity of nonmammals is immense, with a wide variety of body plans, physiologies, and life cycles. Respiratory systems range from gills to lungs to diffusion across membranes. Reproduction includes egg laying, live birth, and complex metamorphosis in some groups. Vertebrates exhibit a spectrum from birds with feathers to reptiles with scales to amphibians with permeable skin, while invertebrates include highly varied forms such as insects, mollusks, crustaceans, cnidarians, and echinoderms. The ecological roles of nonmammals are likewise broad, including pollination, predation, herbivory, scavenging, and nutrient cycling.

Nonmammals have substantial economic and ecological importance, providing food, disease vectors, and models for scientific research. They face threats from habitat loss, pollution, climate change, and overexploitation in some cases. The term’s main caveat is that it lumps together a gigantic and diverse set of organisms, so scientists usually prefer more precise classifications such as vertebrates vs invertebrates or by class and phylum.