Green Iguana

Type: Reptile
Diet: Herbivore
Average lifespan in the wild: 20 years
Size: 6.6 ft (2 m)
Weight: 11 lbs (5 kg)

Green, or common, iguanas are among the largest lizards in the Americas, averaging around 6.5 feet (2 meters) long and weighing about 11 pounds (5 kilograms).

They are also among the most popular reptile pets in the United States, despite being quite difficult to care for properly. In fact, most captive iguanas die within the first year, and many are either turned loose by their owners or given to reptile rescue groups.

The green iguana’s extensive range comprises the rain forests of northern Mexico, Central America, the Caribbean Islands, and southern Brazil. They spend most of their lives in the canopy, descending only infrequently to mate, lay eggs, or change trees.

Primarily herbivores, iguanas are active during the day, feeding on leaves, flowers, and fruit. They generally live near water and are excellent swimmers. If threatened, they will leap from a branch, often from great heights, and escape with a splash to the water below. They are also tough enough to land on solid ground from as high as 40 feet (12 meters) and survive.

Iguanas' stout build gives them a clumsy look, but they are fast and agile on land. They have strong jaws with razor-sharp teeth and sharp tails, which make up half their body length and can be used as whips to drive off predators. They can also detach their tails if caught and will grow another without permanent damage.

Other members of the iguana family include the Fiji Island banded iguana, the desert iguana, and the Galápagos Islands marine iguana. Their appearance, behavior, and endangered status vary from species to species.

Saltwater Crocodile

Type: Reptile
Diet: Carnivore
Average lifespan in the wild: 70 years
Size: 17 ft (5 m)
Weight: 1,000 lbs (450 kg)
Group name: Bask (on land) or float (in water)

Earth’s largest living crocodilian—and, some say, the animal most likely to eat a human—is the saltwater or estuarine crocodile. Average-sized males reach 17 feet (5 meters) and 1,000 pounds (450 kilograms), but specimens 23 feet (7 meters) long and weighing 2,200 pounds (1,000 kilograms) are not uncommon.

Saltwater crocs, or "salties," as Australians affectionately refer to them, have an enormous range, populating the brackish and freshwater regions of eastern India, Southeast Asia, and northern Australia. They are excellent swimmers and have often been spotted far out at sea.

Classic opportunistic predators, they lurk patiently beneath the surface near water's edge waiting for potential prey to stop for a sip of water. They’ll feed on anything they can get their jaws on, including water buffalo, monkeys, wild boar, and even sharks. Without warning, they explode from the water with a thrash of their powerful tails, grasp their victim, and drag it back in, holding it under until the animal drowns.

Population estimates range from 200,000 to 300,000 worldwide, and they are considered at low risk for extinction. But saltwater croc hides are valued above all other crocodilians, and illegal hunting, habitat loss, and antipathy toward the species because of its reputation as a man-eater continue to put pressure on the population.

Spring Peeper

Type: Amphibian
Diet: Carnivore
Average lifespan in the wild: 3 years (estimated)
Size: 1 in (2.5 cm)
Weight: 0.11 to 0.18 oz (3 to 5 g)
Group name: Army

Spring peepers are to the amphibian world what American robins are to the bird world. As their name implies, they begin emitting their familiar sleigh-bell-like chorus right around the beginning of spring.

Found in wooded areas and grassy lowlands near ponds and swamps in the central and eastern parts of Canada and the United States, these tiny, well-camouflaged amphibians are rarely seen. But the mid-March crescendo of nighttime whistles from amorous males is for many a sign that winter is over.

Spring peepers are tan or brown in color with dark lines that form a telltale X on their backs. They grow to about 1.5 inches (3.8 centimeters) in length, and have large toe pads for climbing, although they are more at home amid the loose debris of the forest floor.

They are nocturnal creatures, hiding from their many predators during the day and emerging at night to feed on such delicacies as beetles, ants, flies, and spiders.

They mate and lay their eggs in water and spend the rest of the year in the forest. In the winter, they hibernate under logs or behind loose bark on trees, waiting for the spring thaw and their chance to sing