Why are dolphins & mammals classed as mammals?
They have mammary glands to feed their young and have three ossicles (auditory bones). Their brain contains a neocortex region. Cetaceans even have hair at one point. They are warm blooded and breathe with lungs. These are all characteristics whales and dolphins share with other mammals. Mammal is just the name for animals which share these certain characteristics, meaning they are related closer to each other than to other classes of animals. Live young isn’t just a characterisitc of mammals, as other classes of animals, reptiles etc are oviviparous, meaning the young are still nourished by the egg, but the mother still gives birth to live young. Endothermy isn’t used instead of warm bloodedness. Endothermy is more of a feature of thermoregulation, where an organisms’ metabolic rate is increased to produce more heat. Cetaceans are warm blooded animals, not just endothermic, because they are also tachymetabolic and they are homeothermic through endothermy. These three factors allow cet
