Reptiles Continued Flashcards
Temperature control
Reptiles occur throughout the world but are more common in Tropical habitats.
Most non-avian reptiles are ectothermic, meaning they cannot generate metabolic heat.
However, some regulate their internal body temperature through behavior, such as sunning, and can operate at higher temperatures than endothermic (“warm-blooded”) birds and mammals.
Some reptiles may also survive temperatures as low as freezing, although in these conditions their bodily functions operate at a very reduced rate.
Extreme habitats
By obtaining all their heat from external sources such as the sun, ectothermic reptiles can survive easily on 1/10th of the amount of food needed by an endothermic animal of the same size—endotherms use up a large portion of the energy obtained from food just to maintain a constant body temperature.
This gives non-avian reptiles a great advantage in habitats where conditions are extreme and food is short supply, notably desserts, where lizards are often the most common form of vertebrate life.
Order: Chelonia
Turtles and tortoises - heavily armored reptiles with bony shells that originate from their ribs and cover the top and bottom of their bodies. This gives them excellent protection from predators but limits their speed and agility on land.
They lack teeth and instead use a sharp horny “beak” to break up their food, which may consist of animal or vegetable material, or both, depending on the species. Turtles occur on the land (where they are often known as tortoises), in freshwater and in the sea.
They all lay nearly spherical eggs, with some marine species laying up to 100 in a clutch.
Order: Rhynchocephalia
Tuatara
Both surviving members of this order live on islands off the coast of New Zealand. Despite their lizardlike appearance, they are not squamates and belong to an ancient group of reptiles that was formerly spread over much of the world.
Their teeth are fused to their jawbones and those on the tip of their upper jaw are modified into a beaklike arrangement.
They lack the hemi penis (double penis) unique to squamates. They lay eggs, which take about a year to hatch, and have long life spans.
Order: Squamata
Lizard, Snakes, and Amphisbaenians (worm-lizards)
This is the largest group of ectothermic reptiles, with the widest distribution.
Most lay eggs but a sizable proportion bear live young.
Lizards are the most numerous group and are distinguished by the presence of legs, although limblessness have evolved many times amount squamates. They also have eyelids and external ear openings.
The worm-lizards are burrowing squamates restricted to warm climates. Their scales are arranged in annuli (rings) and their skulls are bony, allowing them to force their way through hardened soil. Most worm-lizards have no limbs but the ajolotes or mole lizards (Bipedidae) have front limbs that they use to dig.
Snakes are elongated squamates lacking legs, eyelids, and external ear openings. These constraints have resulted in specialized methods of locomotion and hunting. All snakes are carnivorous feeding on animals ranging from ants to antelopes.
Order: Crocodilia
Crocodiles, Alligators, and Gharials
One of the the 2 surviving groups from an evolutionary live that also contained the extinct dinosaurs, the other survivors being the birds.
Crocodilians are covered with thick bony plates and are semiaquatic predators. Their social behavior, complex displays, and vocalizations set them apart from all other reptiles.
All species lay eggs, and females show a high degree of parental care.
Most live in freshwater rivers, lakes, and lagoons, while few species inhabit tidal reaches and may venture out to sea.
