Reptiles

Reptiles Do not regulate their own internal body temperature – Must rely on the environment’s temperature to warm their bodies Move in and out of the sun to regulate temperature (think snakes and alligators warming their bodies in the sunlight) Because they are ectotherms, they are not found in cold environments LAY EGGS WITH SHELLS!!!

Reptiles (continued) Have scaly skin– Prevents loss of body moisture and provides additional protection from predators Must rely on lungs for respiration Legs placed more directly under the body compared to amphibians (which have legs at the sides of the body) – Can support a greater body weight compared to amphibians (think crocodiles vs. salamanders)

Feeding in Reptiles Herbivores and carnivores

Sense and Response in Reptiles In some snakes, heat sensitive organs can detect prey Snakes use their tongue to “taste air”

Circulation in Reptiles Most reptiles have three-chambered hearts Crocodiles have four-chambered hearts

Reproduction in Reptiles Occurs on land – lay eggs – amniotic egg allowed reptiles to live on land – major evolutionary advancement Amniotic egg – provides nourishment to the embryo and contains membranes that protect it during development Internal fertilization – eggs laid after fertilization

The Amniotic Egg Amnion Embryo Allantois The chorion regulates the transport of oxygen from the surface of the egg to the embryo and carbon dioxide, one product of respiration, in the opposite direction. This baglike structure contains a yolk that serves as a nutrient-rich food supply for the embryo. The amnion is a fluid-filled sac that surrounds and cushions the developing embryo. It produces a protected, watery environment. The allantois stores the waste produced by the embryo. It also serves as a respiratory organ. Chorion Yolk sac Shell

Groups of Reptiles 4 major groups of reptiles: Turtles and tortoises Crocodilians Snakes and lizards Tuatara

Turtles and Tortoises Shells (upper part called carapace) are part of the skeleton/backbone Some aquatic others terrestrial (better known as tortoises

Crocodilians Major predators Crocodiles vs. alligators – crocodiles have narrower snouts Seen basking in sun with mouths open

Snakes and Lizards Found in many different environments – from trees to deserts

Tuatara Most primitive group of reptiles

Birds

Birds Birds are endotherms – Maintain constant internal body temperature Feathers reduce heat loss Holding wings away from body and panting releases excess heat Must eat large amounts of food to sustain high levels of energy

Birds (continued) Only organisms with feathers – Lightweight, modified scales that provide insulation and allows for flight Preening (grooming) keeps feathers in good condition – birds also rub oil from glands over their feathers for waterproofing Molting – shedding of old feathers for new feathers

Two Feather Types Contour – long, rigid and used for flight Down – small, fluffy, soft and used for insulation

Movement in Birds Powerful flight muscles attached to sternum (breastbone)

Feeding in Birds Shape of bird’s beak gives clues to types of food eaten Hummingbirds vs. pelicans vs. hawks

Respiration in Birds Lungs with anterior and posterior air sacs – need these sacs to assist with need for great deal of oxygen for flight muscles

Circulation in Birds Four-chambered heart for efficiency Need four chambers for flying

Reproduction in Birds Occurs on land – lay eggs – amniotic egg Amniotic egg – provides nourishment to the embryo and contains membranes that protect it during development Internal fertilization – eggs laid after fertilization

Diversity of Birds Common uniformity, but can exhibit specific adaptations to environments (hawks vs. penguins)