Vocabulary
convergent adaptation The appearance of similar traits in groups of animals that are
evolutionarily unrelated to each other.
ecdysis The ability to regenerate lost limbs, as well as other body parts.
hyoid bone A U-shaped bone at the root of the tongue; in salamanders it is used to help
catch prey.
tympanum Equivalent to the middle ear; used in hearing.
valarian respiration Respiration in which the capillary beds are spread throughout the
epidermis, so that gases can be exchanged through the skin.
Points to Consider
- Future studies of molecular genetics should soon provide further insights to the evolu-
tionary relationships among frog families. These studies will also clarify relationships
among families belonging to the rest of vertebrates as well. - Toxins obtained from some frog species may have potential as therapeutic drugs. The
alkaloid epibatidine, a painkiller 200 times more potent than morphine, is found in
some species of poison dart frogs. Other chemicals isolated from frog skin may offer
resistance to HIV infection. As we will see in the next lesson, reptiles also possess
chemicals and unique genes that are useful for medical purposes. - Although care of offspring is poorly understood in frogs, it is estimated that up to
20% of amphibian species care for their young, and that there is a great diversity of
parental behaviors. As you begin to examine the reproductive system of reptiles in the
next lesson, think about what kinds of parental behaviors reptiles might have and how
they compare to that of amphibians.
13.4 Lesson 13.4: Reptiles
Lesson Objectives
- List reptile traits.
- Describe the general features of lizards and snakes.
- List the characteristics of alligators and crocodiles.
- Describe the traits of turtles.
- Explain the importance of reptiles.