2 Vertebrates 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.
3 FishHave 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
4 Amphibians 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
5 Reptiles Tough, dry skin covered by scales Obtain oxygen from air with lungsLay eggs, which have shells, on land.Ex: snakes, lizards, alligators
6 EctothermsAmphibians 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.
7 Birds 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
8 Mammals 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
9 EndothermBird and mammals are endotherms, which means their body maintains a constant body temperature.Birds and mammals have many adaptations to help maintain body temperature