Average life span in the wild: 10 to 15 years
Size: Up to 12 in (30 cm)
Weight: 2.11 to 8 oz (60 to 227 g)
Protection status: Endangered
Did you know? Because they have the ability to regenerate lost body parts, axolotls are probably one of the most scientifically studied salamanders in the world.
The Mexican axolotl (pronounced ACK-suh-LAH-tuhl) salamander has the rare trait of retaining its larval features throughout its adult life. This condition, called neoteny, means it keeps its tadpole-like dorsal fin, which runs almost the length of its body, and its feathery external gills, which protrude from the back of its wide head.
Found exclusively in the lake complex of Xochimilco (pronounced SO-chee-MILL-koh) near Mexico City, axolotls differ from most other salamanders in that they live permanently in water. In extremely rare cases, an axolotl will progress to maturity and emerge from the water, but by and large, they are content to stay on the bottom of Xochimilco’s lakes and canals.
Close relatives of the tiger salamander, axolotls can be quite large, reaching up to a foot (30 centimeters) in length, although the average size is closer to half that. They are typically black or mottled brown, but albino and white varieties are somewhat common, particularly among captive specimens.
Axolotls are long-lived, surviving up to 15 years on a diet of mollusks, worms, insect larvae, crustaceans, and some fish. Accustomed to being a top predator in its habitat, this species has begun to suffer from the introduction of large fish into its lake habitat. Natural threats include predatory birds such as herons.
Populations are in decline as the demands of nearby Mexico City have led to the draining and contamination of much of the waters of the Xochimilco Lake complex. They are also popular in the aquarium trade, and roasted axolotl is considered a delicacy in Mexico, further shrinking their numbers. They are considered a critically endangered species.
Average life span in the wild: 12 years
Size: 21 in (50 cm)
Weight: 14.4 oz (408 g)
Did you know? Chameleons don't change colors to match their surroundings. Each species displays distinct color patterns to indicate specific reactions or emotions.
The Meller's chameleon is the largest of the chameleons not native to Madagascar. Their stout bodies can grow to be up to two feet (two-thirds of a meter) long and weigh more than a pound (one-half kilogram).
Meller's distinguish themselves from their universally bizarre-looking cousins with a single small horn protruding from the front of their snouts. This and their size earn them the common name "giant one-horned chameleon."
They are fairly common in the savanna of East Africa, including Malawi, northern Mozambique, and Tanzania. Almost one-half of the world’s chameleons live on the island of Madagascar.
As with all chameleons, Meller's will change colors in response to stress and to communicate with other chameleons. Their normal appearance is deep green with yellow stripes and random black spots. Females are slightly smaller, but are otherwise indistinguishable from males.
They subsist on insects and small birds, using their camouflage and a lightning-fast, catapulting tongue, which can be up to 20 inches (50 centimeters) long, to ambush prey.
Exotic pet enthusiasts often attempt to keep Meller's chameleons as pets. However, they are highly susceptible to even the slightest level of stress and are very difficult to care for in captivity. In the wild, they can live as long as 12 years.
Average life span in captivity: Up to 20 years
Size: 37 to 70 in (94 to 179 cm)
Weight: Adults: 15 to 22 pounds (7 to 10 kg)
Protection status: Endangered
Did you know? Matschie's tree kangaroos can leap 60 feet (18 meters) to the ground from trees without getting hurt.
Tree kangaroos are found only in the rain forests of Australia, West Papua, and Papua New Guinea. Six of ten species are found in Papua New Guinea, in some of the last undisturbed rain forest habitat in the world.
The Matschie's tree kangaroo (Dendrolagus matschiei) is endemic to the Huon Peninsula on the northeast coast of Papua New Guinea. It is classified by the International Union for the Conservation of Nature (IUCN) 2004 Red List as endangered.
Matschie's tree kangaroos live in mountainous cloud forests at elevations of up to 11,000 feet (3,350 meters). They spend most of their time in trees. Tree kangaroos primarily eat tree leaves. They also consume flowers, grass shoots, ferns, moss, and bark.
Female tree kangaroos give birth to one offspring after a gestation period of approximately 44 days. After birth, the fetus-like young, called a joey, crawls to a teat located inside the mother's pouch, where it attaches itself to nurse. The majority of the infant's development occurs during this lactation phase.
The joey remains in the pouch for about ten months. The mother will clean her pouch and groom the infant often during this phase. After the infant initially leaves the pouch at eight months, it will continue to return to the pouch to nurse. This "in and out" phase lasts for one or two months. During the final phase, the young still nurses but never climbs completely into the pouch.
Young tree kangaroos are weaned when they are approximately 13 months old. They stay with their mothers until they are about 18 months old, when they disperse and establish a home range.
Little is known about the social behavior of wild tree kangaroos. Researchers believe that Matschie's tree kangaroos are fairly solitary animals. Females and males have non-overlapping home ranges, but a male's range will overlap several females' range. Researchers also believe that Matschie's tree kangaroos are polygamous and that males interact with several females. Males, however, appear not to establish harems, and females remain independent. The only strong social bond these animals form is between mother and offspring.
In captivity, if females are isolated from all other animals after becoming pregnant, offspring almost always survive. These observations show that Matschie's tree kangaroos are mostly solitary animals.
Average life span in the wild: 5 to 12 years
Size: 4 to 5 ft (1.2 to 1.5 m)
Weight: 1 to 3.3 lbs (.5 to 1.5 kg)
Protection status: Threatened
Did you know? Marine iguanas sneeze frequently to expel salt from glands near their noses. The salt often lands on their heads, giving them a distinctive white wig.
The much-maligned marine iguanas of the Galápagos Islands are so famously homely, even Charles Darwin piled on, describing them as "hideous-looking" and "most disgusting, clumsy lizards."
It's true, they're not pretty, with their wide-set eyes, smashed-in faces, spiky dorsal scales, and knotty, salt-encrusted heads. But what these unusual creatures lack in looks they make up for with their amazing and unique ecological adaptations.
Scientists figure that land-dwelling iguanas from South America must have drifted out to sea millions of years ago on logs or other debris, eventually landing on the Galápagos. From that species emerged marine iguanas, which spread to nearly all the islands of the archipelago. Each island hosts marine iguanas of unique size, shape and color.
They look fierce, but are actually gentle herbivores, surviving exclusively on underwater algae and seaweed. Their short, blunt snouts and small, razor-sharp teeth help them scrape the algae off rocks, and their laterally flattened tails let them move crocodile-like through the water. Their claws are long and sharp for clinging to rocks on shore or underwater in heavy currents. They have dark gray coloring to better absorb sunlight after their forays into the frigid Galápagos waters. And they even have special glands that clean their blood of extra salt, which they ingest while feeding.
Their population is not well known, but estimates are in the hundreds of thousands. They are under constant pressure from non-native predators like rats, feral cats, and dogs, who feed on their eggs and young. They are protected throughout the archipelago and are considered vulnerable to extinction.
Average life span in the wild: 20 years
Size: 3 ft (90 cm)
Weight: 77 lbs (35 kg)
Group name: Troop
Protection status: Threatened
Mandrills are the largest of all monkeys. They are shy and reclusive primates that live only in the rain forests of equatorial Africa.
Mandrills are extremely colorful, perhaps more so than any other mammal. They are easily identifiable by the blue and red skin on their faces and their brightly hued rumps. These distinctive colors become brighter when the animal is excited. They also have extremely long canine teeth that can be used for self-defense—though baring them is typically a friendly gesture among mandrills.
These are primarily terrestrial monkeys, and they move with long arms to forage on the ground for fruits, roots, and animals such as insects, reptiles, and amphibians. Their cheeks have built-in pouches that are used to store snacks for later consumption. Though mandrills spend much of their time on the ground, they can climb trees and do so to sleep.
Mandrills live in troops, which are headed by a dominant male and include a dozen or more females and young. They also gather in multi-male/multi-female groups that can include some 200 individuals.
These colorful primates are threatened. They are often hunted as bushmeat, and many Africans consider them to be a delicacy. Mandrills are feeling the squeeze of spreading agriculture and human settlement—both are shrinking their rain forest homeland.
Average life span in the wild: 40 years
Size: 8 to 13 ft (2.4 to 4 m)
Weight: 440 to 1,300 lbs (200 to 600 kg)
Protection status: Endangered
Manatees are sometimes called sea cows, and their languid pace lends merit to the comparison. However, despite their massive bulk, they are graceful swimmers in coastal waters and rivers. Powering themselves with their strong tails, manatees typically glide along at 5 miles (8 kilometers) an hour but can swim 15 miles (24 kilometers) an hour in short bursts.
Manatees are usually seen alone, in pairs, or in small groups of a half dozen or fewer animals. From above the water's surface, the animal's nose and nostrils are often the only thing visible. Manatees never leave the water but, like all marine mammals, they must breathe air at the surface. A resting manatee can remain submerged for up to 15 minutes, but while swimming, it must surface every three or four minutes.
There are three species of manatee, distinguished primarily by where they live. One manatee population ranges along the North American east coast from Florida to Brazil. Other species inhabit the Amazon River and the west coast and rivers of Africa.
Manatees are born underwater. Mothers must help their calves to the surface so that they can take their first breath, but the infants can typically swim on their own only an hour later.
Manatee calves drink their mothers' milk, but adults are voracious grazers. They eat water grasses, weeds, and algae—and lots of them. A manatee can eat a tenth of its own massive weight in just 24 hours.
Manatees are large, slow-moving animals that frequent coastal waters and rivers. These attributes make them vulnerable to hunters seeking their hides, oil, and bones. Manatee numbers declined throughout the last century, mostly because of hunting pressure. Today, manatees are endangered. Though protected by laws, they still face threats. The gentle beasts are often accidentally hit by motorboats in ever more crowded waters, and sometimes become entangled in fishing nets.
Size: Head and body, 32 to 40 in (80 to 100 cm); Tail, 4 to 8 in (10 to 20 cm)
Weight: 22 to 44 lbs (10 to 20 kg)
Protection status: Threatened
The lynx is a solitary cat that haunts the remote northern forests of North America, Europe, and Asia. Lynx are covered with beautiful thick fur that keeps them warm during frigid winters. Their large paws are also furry and hit the ground with a spreading toe motion that makes them function as natural snowshoes.
These stealthy cats avoid humans and hunt at night, so they are rarely seen.
There are several species of lynx. Few survive in Europe but those that do, like their Asian relatives, are typically larger than their North American counterpart, the Canada lynx.
All lynx are skilled hunters that make use of great hearing (the tufts on their ears are a hearing aid) and eyesight so strong that a lynx can spot a mouse 250 feet (75 meters) away.
Canada lynx eat mice, squirrels, and birds, but prefer the snowshoe hare. The lynx are so dependent on this prey that their populations fluctuate with a periodic plunge in snowshoe hare numbers that occurs about every ten years. Bigger Eurasian lynx hunt deer and other larger prey in addition to small animals.
Lynx mate in early spring or late winter. About two months later, females give birth to a litter of one to four young.
Humans sometimes hunt lynx for their beautiful fur. One endangered population, the Iberian lynx, struggles to survive in the mountains of Spain, far from the cold northern forests where most lynx live.
Average life span in the wild: More than 50 years
Size: 36 in (90 cm)
Weight: 253 lbs (115 kg)
Group name: Flotilla
Protection status: Endangered
Did you know? Sea turtles can move through the water at speeds of up to 15 mi (24 km) per hour.
Loggerhead turtles are the most abundant of all the marine turtle species in U.S. waters. But persistent population declines due to pollution, shrimp trawling, and development in their nesting areas, among other factors, have kept this wide-ranging seagoer on the threatened species list since 1978.
Their enormous range encompasses all but the most frigid waters of the world's oceans. They seem to prefer coastal habitats, but often frequent inland water bodies and will travel hundreds of miles out to sea.
The largest of all hard-shelled turtles—leatherbacks are bigger but have soft shells—loggerheads have massive heads, strong jaws, and a reddish-brown shell, or carapace. Adult males reach about three feet (nearly one meter) in shell length and weigh about 250 pounds (113 kilograms), but large specimens of more than 1,000 pounds (454 kilograms) have been found.
They are primarily carnivores, munching jellyfish, conchs, crabs, and even fish, but will eat seaweed and sargassum occasionally.
Mature females will often return, sometimes over thousands of miles, to the beach where they hatched to lay their eggs. Worldwide population numbers are unknown, but scientists studying nesting populations are seeing marked decreases despite endangered species protections.