1. Reptiles are ectothermic vertebrates.
2. Their skin has scales, but no hair or feathers.
3. They have three-chambered hearts (except for alligators and crocodiles, which have four-chambered hearts).
4. They have claws on their toes (except those which do not have legs, such as legless lizards).
5. They are the first animals, in evolution, to develop the amniotic egg. This allows reptiles to lay eggs on land.
You already knew all the facts that are in bold, didn't you? Let's think of the various kinds of reptiles at Cazadero, and review what we already know about them.
The most common reptile that you can find at Cazadero is the alligator lizard, usually crawling though the leaves and debris on the ground, looking for invertebrates to munch and lunch on. You may also see garter snakes along the creek side, blue belly lizards sunning themselves on rocks or logs, or the rare turtle in the creek.
What do all these reptiles have in common? They all are cold-blooded (the reason lizards and snakes sun themselves is to warm up, just like you on a cold morning, or after a wade in Austin Creek) and they have scales. Did you ever see a lizard with feathers, or a hairy snake? No! Scales make up their only covering. Reptiles also lay eggs on dry land. You have heard of turtle eggs, right? Nature shows often have programs on sea turtles and how they lay their eggs on the beach. You may have seen some nature programs on alligators, another kind of reptile but not one we have, laying eggs in piles of rotting vegetation. All reptiles lay eggs. We know now that birds evolved from reptiles, and one of their linkages is the fact that they both lay hard-shelled eggs on dry land. Amphibian eggs, in comparison, are soft and must be laid in water.
Snakes, turtles, and lizards are all reptiles because they are cold-blooded, they lay eggs on dry land, and are covered with scales, never feathers or fur.
