Amphibians and Reptiles

Objectives

• Explain how fish reproduce and develop
• Describe structure of amphibians
• Outline reproduction and development of amphibians
• Overview reptiles

In oviparous fish, fertilization is external. Eggs are laid and embryos develop outside the mother's body.

In sharks, eggs develop inside the mother without nourishment from the mother. (ovoviviparous)

Untitled Slide

• Spawning common
• Mouth brooding
• Larvae go through metamorphosis

Amphibians

Amphibians

• First true tetrapods
• Skin contains keratin
• Ectothermic
• Digestive, excretory, and reproductive systems
• Three-chambered heart

Amphibians

• Sense organs for smell and taste
• Frogs have larynx
• Gills as larvae, lungs as adults
• Additional oxygen through skin

Amphibian Reproduction

• Eggs must be laid in water
• Large number of eggs
• Larval stage undergoes metamorphosis

Reptiles

Reptiles

• Scales of keratin
• Have a diaphragm
• Ectotherms
• Most have 3 chambered hearts
• Alligators/crocodiles 4-chambered

Reptiles

• Good eyesight
• Keen sense of smell using tongue

Reptile Reproduction

• Mostly internal fertilization
• Amniotic eggs, unlike amphibians
• No larval stage

Bird Intro

• Endothermic tetrapods
• Amniotic eggs with hard shells
• Wing muscles 35% of bird's mass
• Feathers for flight and insulation
• (Flight feathers and down feathers)