The Compound Heat Shield of the Saharan Silver Ant

THE Saharan silver ant (Cataglyphis bombycina) is one of the most heat-tolerant land animals known. When the midday Saharan sun forces the ant’s predators to seek shade, the ant makes brief forays from its burrow in search of food, which consists of other insects killed by the intense heat.

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Consider: The silver ant’s assets include a compound heat shield made up of a covering of special hairs on the top and sides of its body and a hairless underside. The hairs, which give the ant a silvery sheen, are tiny tubes with a triangular cross section. Their two outward-facing surfaces have microscopic corrugations that run the length of the hair, while the inward-facing surface is smooth. This design serves two functions. First, it enables the hairs to reflect solar radiation in the visible and near-infrared ranges. Second, it helps the ant to dissipate body heat absorbed from the environm ... Read more »

The Sea Otter’s Fur

MANY aquatic mammals that live in cold waters have a thick layer of blubber under the skin to help them stay warm. The sea otter relies on another insulation method—a thick fur coat.
Consider: The fur of the sea otter is denser than that of any other mammal, with some one million hairs per square inch (155,000 per sq cm). When the otter swims, its coat traps a layer of air close to its body. That air acts as an insulator, preventing the cold water from coming into direct contact with the animal’s skin and sapping its body heat.
Scientists believe that there is a lesson to be learned from the sea otter’s fur. They have experimented with a number of artificial fur coats, varying such factors as hair length and hair spacing. The researchers have concluded that “the denser and the longer the hairs are, the dryer or the more water-repellent the hairy surface is.” Put another way, sea otters can boast a tru ... Read more »

The Landing Strategy of the Honeybee

HONEYBEES can safely land at virtually any angle without problems. How do they do it?
Consider: A safe landing requires that the honeybee reduce its approach speed to nearly zero before contact. One logical way to do this would be to measure two factors—flight speed and the distance to the target—and then reduce speed accordingly. However, that method would be difficult for most insects because they have close-set, fixed-focus eyes that cannot directly measure distance.
The vision of honeybees is very different from that of humans who use binocular vision. Honeybees seem to use the simple fact that an object appears to get bigger as they approach it. The closer they get to an object, the faster it seems to increase in size. Experiments conducted at the Australian National University indicate that the honeybee decreases its flight speed so that the rate of apparent enlargement of an object remains constant. B ... Read more »

 
The Whales Are Here!
 
Every year, beginning in July, female southern right whales (Eubalaena australis) arrive at the southern coast of Santa Catarina, Brazil. They come from as far as the subantarctic, thousands of miles away, to give birth and nurse their calves in shallow waters. For several months residents and tourists at the beaches or on the cliffs are thrilled to watch the whales—mothers and calves resting or frolicking in the water! *
 
Giant Acrobatic Marine Creatures
A female can be 52 feet (16 m) long, about the size of an articulated bus, and weigh up to 80 tons! Its massive body is generally black, sometimes with white patches on the belly. The head is enormous, a quarter of the entire body length. The mouth is long and arched. This whale has no dorsal fin as do some other species. To swim forward, it flexes its broad and deeply notched tail up and down, instead of side to side as fish do. To change direction, ... Read more »

The Flipper of the Humpback Whale

THE adult humpback whale is bigger and heavier than a city bus. Still, this colossal mammal is remarkably agile when diving and turning. How can the humpback whale be so nimble? Part of the secret lies in the bumps on its flippers.
Consider: Most whales and other cetaceans have flippers with smooth leading edges. However, the humpback whale is different. It has uniquely large bumps (called tubercles) on the leading edge of its flippers. As the humpback swims, water flows over the bumps and breaks up into a multitude of vortices. The bumps channel the water flow and create turbulence. This “tubercle effect” provides the whale with more lift, allowing it to tilt its flippers at a high angle without stalling. At high angles these bumps also reduce drag—an important benefit for the humpback’s long flippers, each being about one third of the whale’s body length.
Researchers are applying this concept to ma ... Read more »

The Crocodile’s Jaw

THE crocodile has the most powerful bite ever measured for animals that are now living. For example, the saltwater crocodile, found near Australia, can bite nearly three times as hard as a lion or a tiger. Yet, the crocodile’s jaw is also incredibly sensitive to touch—even more sensitive than the human fingertip. How can that be, considering the crocodile’s armored skin?
The crocodile’s jaw is covered with thousands of sense organs. After studying them, researcher Duncan Leitch noted: “Each of the nerve endings comes out of a hole in the skull.” This arrangement protects the nerve fibers in the jaw while providing sensitivity that in some spots is greater than instruments could measure. As a result, the crocodile can distinguish between food and debris in its mouth. That is also how a mother crocodile can carry her hatchlings in her mouth without accidentally crushing them. The crocodile’s jaw is a sur ... Read more »

The Parrot Fish—A Sand-Making Machine?

WHERE does sand come from? There are many sources. But the one described in this article might surprise you. It is a fish that grinds coral into fine sand—the parrot fish!
Parrot fish live in various tropical waters throughout the world. After swallowing crushed coral, they extract tiny food morsels and then expel the rest in the form of sand. To do its job, the parrot fish uses its powerful beaklike jaws and strong back teeth. Some species can live as long as 20 years, without wearing out their teeth.
In some areas, by busily chomping away on dead coral, the parrot fish produces more sand than any other natural sand-making process. Some researchers estimate that a typical parrot fish produces hundreds of pounds (kg) of sand a year.

Swarthy parrot fish
The parrot fish performs another vital task. As it grazes intensively on dead, algae-coated coral and vegetable material, it also keeps the coral cle ... Read more »

The Light Organ of the Hawaiian Bobtail Squid

A NOCTURNAL hunter, the Hawaiian bobtail squid creates its own light—not to be seen, but to be unseen—to blend in with the ambient moonlight and starlight. The animal’s secret is its partnership with light-emitting bacteria. That partnership may also hold secrets that could benefit us, but in a seemingly unrelated way. It may benefit our health.
Consider: The Hawaiian bobtail squid lives in the clear coastal waters of the Hawaiian Islands. Light from the moon and the stars would normally make the silhouette of the creature stand out to predators below. The bobtail squid, however, emits a glow from its underside that mimics ambient night light in both intensity and wavelength. The result is stealth—no silhouette, no shadow. The squid’s “high-tech” apparatus is its light organ, which houses bioluminescent bacteria that produce just the right glow to camouflage their host.
The ba ... Read more »

Big Eyes—Tiny Body!

MOST would call it cute; some might call it bizarre. It has spindly legs, soft fur, and huge shining eyes. Its body is about five inches (12.5 cm) in length, and it weighs about four ounces (114 g). What is it? It is the tarsier!
Let’s take a closer look at one of these creatures, the Philippine tarsier. Its eyes, ears, hands, feet, legs, and tail all seem too big for its tiny body. Yet, a closer look at this oddity reveals ingenious design.
HEARING: The tarsier’s paper-thin ears can furl, unfurl, and turn to pick up the faintest sounds. Its keen hearing helps it not only to avoid predators, such as wild cats, but also to locate prey. After dark, the tarsier’s ears will tune in to the sound of crickets, termites, beetles, birds, and frogs. Then its whole head will follow, directing those bulging eyes toward its prospective meal.
GRIP: The tarsier’s hands are tailor-made for grasping thin branches. Its finger ... Read more »

Airborne Gardeners of the Tropical Rain Forest

AS ANY gardener knows, successful cultivation depends on sowing seeds in the right place at the right time. Strange as it may seem, however, some of the most effective sowing in the rain forest is done at night—and from the air. The airborne gardeners doing the sowing are Old World fruit bats—some of which are known as flying foxes. *
Spreading the Seed
Most fruit bats fly around at night, scouring the forest for trees that offer them tasty fruit or flowers rich in nectar. As they go about their aerial foraging, the bats digest fruit and expel undigested pulp and seeds. To complete their gardening work, they also pollinate flowers while sipping the nectar they enjoy so much.
Since fruit bats may cover long distances during the night, they can disperse seeds over a wide area. And because the bats pass some seeds through their digestive tract, they also provide “fertilizer” that encourages ... Read more »