2Vertebrates Animals with backbones All vertebrates have an endoskeleton, an internal support system that makes the animal more flexible and easier to move.The 5 groups are birds, fish, amphibians, reptiles, and mammals.
3FishHave gills, a respiratory organ that filters oxygen dissolved in water.Have sensory organs for taste, odor, and sound.Female fish lay eggs that are fertilized by a certain male. Eggs develop and hatch on their own
4Amphibians Lay eggs in water Smooth, moist skin Skin works as a respiratory organ only when wet.Can live in moist land environments as adults.Ex: Frogs, toads, salamanders
5Reptiles Tough, dry skin covered by scales Obtain oxygen from air with lungsLay eggs, which have shells, on land.Ex: snakes, lizards, alligators
6EctothermsAmphibians and reptiles are ectotherms, animals whose body temperatures changes with environmental conditions.For example, on a cool day, a tortoise’s body will be cooler than it is on a hot one.
7Birds Have feathers and beaks Have a pair of scaly legs and a pair of wingsTheir eggs have hard shells.Mothers sit on their eggs to keep them warm (incubation)Hollow bones
8Mammals Have hair or fur Contain body fat to store energy or maintain body temperatureFemales produce milk to feed their youngIn most mammals, offspring develop inside the female’s body
9EndothermBird and mammals are endotherms, which means their body maintains a constant body temperature.Birds and mammals have many adaptations to help maintain body temperature