Nature's Best Photography 2013

53. The hammerhead sharks are named for the unusual shape of their heads. They are found worldwide in warmer waters along coastlines and continental shelves. Unlike most sharks, hammerheads usually swim in schools.

17. Red kangaroos are the largest mammals native to Australia, weighing about 200 pounds and standing nearly 6 feet. Their strong tails keep them balanced when jumping and act as a tripod with their two legs when at rest.

15, 25, 33. <p>The many folds in an elephant’s skin layers aid in the dispersion of body heat. A wet mud bath helps the elephant cool down instantly. Moisture trapped in its wrinkles continues to keep the elephant cool even after it leaves the bath. Mud also protects the elephant's skin from insects, sun, and moisture loss.</p> <p>The elephant’s trunk is important in drinking. Elephants suck water into the lower part of the trunk, then arch the truck and squirt water into the mouth. The only time in its life when an elephant feeds directly with its mouth is when suckling. The infant elephant presses its mouth directly against the breast and curls its trunk out of the way.</p> <p>Female elephants give birth every four to nine years. After a 22-month gestation period, a single elephant calf is born, weighing about 265 pounds (120 kg); twins are very rare. No other land animal takes as long to develop in utero. A short time after birth, they instinctively follow their mothers.</p>

14. The zebra’s gestation period is approximately one year, and one foal is produced per breeding season. Foals are about 55 pounds (25 kg) at birth, with a body length of about 47 inches (120 cm). For the first few weeks, a foal remains close to its mother. She prevents interaction between the foal and other herd members by threatening any individual that comes too close.

34. Historically, the mountain lion’s range was the most extensive of any American terrestrial mammals. They could be found across North America, and from southern Argentina and Chile to southeastern Alaska. Extermination efforts, hunting, and habitat destruction have restricted their range to relatively mountainous, unpopulated areas.

22. Emerald glass frogs are delicate frogs with transparent skin. They measure up to an inch (2.5 cm) in size. These frogs are nocturnal and are frequently found on low vegetation near rivers and streams in lowland tropical forests, as well as cloud forests in the mountains.

50. Crested macaques are threatened by over-hunting and habitat destruction. Their meat is considered a delicacy in Sulawesi. Human expansion for settlement and agriculture has diminished their habitat. Sulawesi is particularly sensitive to these worldwide problems. As an island, space is severely limited for the needs of wildlife and an expanding human population.

09. Bonobos are highly intelligent, social animals. In the wild, they live in stable communities of up to 150 members; however, they usually split into smaller groups when foraging or traveling. A single offspring is born after gestating for eight months and will be cared for by its mother for almost five years.

52. Chimpanzees are an endangered species found predominantly in the forests and savanna woodlands of central Africa. They have a highly variable omnivorous. Fruit comprises about half the diet, but leaves, bark, and stems are also important. Small mammals, reptiles, and insects make up a small but significant component of the diet of many populations.

31. In North America, the wild bison population once numbered in the tens of millions. Hunting gradually reduced the herds before the Civil War. After the war, they were pushed almost to extinction with westward expansion. Conservation efforts belatedly began in the 1880s, when only 541 animals were counted. Now there are nearly 500,000 animals, over 90 percent of these live on fenced private lands, managed for commercial purposes.

45, 60. <p>Brown bears can be found in the northern parts of Russia, Alaska, and Canada, with the largest concentration east of the Ural Mountains in the Siberian forests. Brown bears have a wide-ranging diet, depending upon the season. They consume mosses, fungi, herbs, grasses, and fruits as well as insects, birds, and fish, especially salmon during their spawning run.</p> <p>Brown bears are solitary, powerful, sometimes aggressive predators. Excellent swimmers, they often feed on spawning salmon, but these omnivores eat anything nutritious. They have acute senses of hearing and smell, but poor eyesight.</p>

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43. Red deer mating season occurs between late September and November. During this time, mature males compete with each other. They size each other up through roaring contests and parallel walking. Evenly matched stags may then escalate by locking antlers, pushing each other, and trying to throw each other off-balance. These competitions can lead to serious injuries and death.

40. These reindeer are only found in Svalbard, an archipelago midway between Norway and the North Pole. They feed on almost any vegetation they find, with few exceptions. They have relatively short legs. During the winter months, their coats grow thicker and longer, making them look even more short-legged and even a starved reindeer look healthy and fat.

11. Lions are the only truly social cats, with related adult females residing together in prides and joined by two to four adult males. Lions have the cognitive ability to recognize individuals and use tactile communication, along with vocalizations and facial expressions, to interact with other lions.

10. At birth, cubs average 11.8 inches long (30 cm) and weigh 0.6 pounds (0.3 kg). They are grayish white in color, with black spots only on the lower body. A mantle of mane-like hair along their back camouflages the cubs in the grass. During the first few weeks of life the cubs are moved every few days by their mother to avoid predators.

19. During the mating season, male African bullfrogs gather in large groups. There they will fight push and bite their way toward the center. The largest males make it to the center and begin calling. The females answer the call by swimming underwater to avoid the smaller males and surface in the center area of a larger male.

41. Chamois live in in a variety of steep, mountainous habitats including alpine meadows, open rocky areas, mixed broadleaf woodland, and coniferous woodland. This species feeds on a wide variety of alpine plants and fungi.

20. The luna moth is an easily distinguishable species in the family Saturniidae. Its wings are a soft, bright green with long, sweeping hind wing tails. Both sexes are similar in size, but males have feather-like antennae twice the width of female’s. The luna moth’s wingspan ranges from 3 to 4.5 inches (7 to 11 cm).

48. The ochre star has a non-centralized nervous system like other echinoderms. They can sense light, contact, chemicals, and water currents from sensory cells in their skin. Ochre stars can be found in shallow waters and bays along the west coast of North America from Alaska to Baja California.