Chordates Chordates Chordates include fish, amphibians, reptiles, birds, and mammals.
All chordates have a hollow nerve cord, a notochord, and pharyngeal slits.
Lateral line fish heart and liver Fish have a lateral line that serves as a sensory organ. They practice external fertilization in wetland areas. Amphibians are experiencing hardship due to environmental problems. Atrazine is an endocrine disrupter in frogs, and methoprin, a mosquito spray, is killing them. Frogs develop missing limbs and also extra limbs.