October 13, 2015

Most everybody knows that elephants are hunted illegally for their ivory. But fewer people know about a type of bird whose ivory is three times as valuable. The bird is the helmeted hornbill of Malaysia and Indonesia, and its survival is being threatened by poaching.

The hornbill, shown in this illustration, is a medium-sized to large tropical bird with a huge, bright red and yellow bill. Its body is covered with black feathers on top and white feathers on its underside. The bird uses its clumsy-looking bill with great skill while eating. WORLD BOOK illustration By Arthur Singer

Elephant ivory comes from the animal’s tusk. The hornbill’s “ivory,” on the other hand, comes from a ridge called a casque on the bird’s upper bill. In most hornbill species, the casque is hollow. But the helmeted hornbill has a solid casque. Males use the heavy casque to batter one another in fights over mates, and both males and females use its weight to help bash into rotten trees, digging out insects to eat.

The casque is made up of a protein called keratin, also found in human fingernails and in animal horns, hooves, and claws. The bird continuously conditions the casque with the same oil used to preen its feathers. The result is a smooth, creamy texture and golden-yellow color that has been prized by carvers in China and Japan for centuries.

Among the local Dayak people, the huge black and white bird—with a wingspread of about 6 feet (2 meters)—is considered a sacred messenger of the gods. It also serves an important role in its rain forest habitat, helping to disperse nuts and seeds in its droppings. Laws protect the helmeted hornbill, but its numbers are threatened by habitat loss in addition to illegal hunting. One researcher estimates that about 6000 helmeted hornbills are killed illegally each year.

October 19, 2012

Scientists at Princeton University reported in mid-October that they had finally determined why elephants have hair: to help them cool down. The result was surprising, because for most mammals, hair helps the body to stay warm.

Many people may be surprised to hear that elephants have hair at all. Actually, elephants have hair all across the head and back. Both African and Asian varieties have hair, though Asian elephants have more of it. Young elephants have noticeably more hair than older elephants do. Granted, elephant hair is rather sparse. The scientists analyzed the density of elephant hair and found that elephants have about 1 hair per square inch (0.16 hair per square centimeter) of skin. The head of a human being has about 1,290 hairs per square inch (200 hairs per square centimeter).

Elephants, like all mammals, have hair at some time in their lives. However, the hair of elephants is very sparse. (World Book illustrations by Jean Helmer)

Because they live in some of the warmest places in the world–countries in Africa and Asia–it is very important for elephants to be able to cool off. Their own body structure, however, makes it very difficult for them to do so. An elephant’s body has a large volume (the space it occupies) compared to the surface area of its skin. So it is difficult for an elephant’s body to shed heat. Elephants typically perform certain behaviors to cool off. They flap their ears, cover themselves in dust and mud to repel sunlight, and use their trunks to spray water on themselves. However, all of these behaviors are still not enough for an elephant to shed the amount of body heat it produces. Apparently, the elephant’s wiry hair also plays a part.

Elephants cool off in several ways, including bathing in water or using their trunks to spray water on themselves. (copyright C. Haagner, Bruce Coleman, Inc.)

The Princeton scientists used data they already had about how animals shed heat. By varying such details as amount of skin surface, width and density of the hair, wind speed, and texture of the skin, they concluded that elephant hairs can enhance the animal’s heat loss from between 5 and 20 percent. They also found the density at which hair on an animal begins to have a cooling effect–about 195 hairs per square inch (30 hairs per square centimeter).

The Princeton research may help to explain why animals developed hair when they did, about 100 million to 300 million years ago. At that time, Earth was much warmer than it is today, and animals needed to be able to cool off. The scientists speculated that animal hair may have evolved into a way to keep bodies warm as the climate cooled.

Even as scientists are learning more about elephants, conservationists are concerned about the ability of the animals to survive. WWF (World Wildlife Fund) officials reported in March 2012 that in Africa, elephants are being hunted virtually to extinction as poachers kill the animals for their ivory tusks.

Additional World Book articles:

• Climate
• Conservation