Req 3 — Spot the Differences

This requirement covers four pairs that people often confuse. The goal is not just to memorize names. It is to notice the body features, habitats, and behaviors that separate one kind of animal from another.

Requirement 3a

Skin and water balance

Amphibians usually have thin, moist skin that helps them exchange water and sometimes oxygen with their surroundings. Because of that, they dry out easily and stay tied to damp habitats or water during at least part of their lives.

Reptiles have dry, scaly skin that helps hold moisture in. That lets them live in much drier places. A reptile can still need shade, water, or shelter, but it does not depend on moist skin the way an amphibian does.

Eggs and life cycle

Most amphibians lay jelly-like eggs in water or very wet places. Many hatch into aquatic young, such as tadpoles, and then transform into adults. Most reptiles lay amniotic eggs with leathery shells on land, or give live birth in some species. Young reptiles usually hatch or are born looking like smaller versions of the adults.

Temperature and lifestyle

Both groups are ectothermic, which means they depend on outside heat sources. But amphibians are usually more limited by moisture, while reptiles are often better adapted for dry heat, basking, and longer movement on land.

Requirement 3b

Snout and teeth

Alligators usually have broader, U-shaped snouts. Crocodiles usually have narrower, more V-shaped snouts. When the mouth is closed, an alligator’s lower teeth are mostly hidden. On a crocodile, a large lower tooth often sticks up where you can see it.

Habitat tolerance

Alligators prefer freshwater more often, although they can handle some brackish water. Crocodiles generally tolerate saltwater better because they have glands that help remove excess salt.

Range and attitude

In the United States, the American alligator is widespread in the Southeast. The American crocodile has a much smaller U.S. range, mainly in South Florida. Crocodiles are often described as more likely to live in coastal environments, while alligators are the more common sight in inland swamps, ponds, and marshes.

Requirement 3c

Skin and build

Frogs usually have smoother, wetter skin and longer hind legs built for jumping. Toads usually have drier, bumpier skin and shorter legs for hopping or walking shorter distances.

Eggs and breeding places

Many frogs lay eggs in clusters or floating masses. Many toads lay eggs in long strings. Both need water for reproduction, but they often choose different breeding sites and have different calling habits.

Habitat and movement

Frogs are often more closely tied to ponds, marshes, and other wet places. Toads can spend more time in drier yards, gardens, and woods, returning to water mainly for breeding.

Requirement 3d

Eyes, ears, and legs

Lizards usually have movable eyelids and visible ear openings. Snakes do not have external ears, and they do not blink because their eyes are covered by a clear protective scale. Most lizards also have legs, while snakes do not.

Tail and body structure

Many lizards can drop part of their tail to escape predators. Snakes cannot do that. Lizards also tend to have more rigid jaw structure than snakes. Snake jaws are built to stretch around larger prey.

How they move and hunt

Snakes move by pushing against the ground with muscles, ribs, and belly scales. Lizards usually run, climb, or crawl using their legs, though some legless lizards can fool people at first glance. Watching the head, eyelids, and ear openings helps you avoid that mistake.

In Req 1, you learned to look for markings and habitat clues. This page adds the bigger comparison skills that keep common mix-ups from tripping you up.