An elephant can achieve a speed of twenty miles an hour, and sustain it for half a day. (source)

There is a species of jellyfish, Turritopsis nutricula, called the "immortal jellyfish", that can theoretically live forever. Unlike other species of jellyfish that die after reaching maturity, the immortal jellyfish is able to revert to an immature polyp state and begin maturing again. It can in theory repeat the process indefinitely. (source)

The largest recorded specimen of the blue whale is 33 meters (110 feet) long—about the height of an 11-storey building. (source)

The Romans were so fond of eating dormice that the upper classes raised them domestically. The rodents were kept in specially designed cages and fed a mixture of nuts.

Three pairs of common English rabbits were let loose in Australia in the middle of the nineteenth century. Within a decade, the six rabbits had multiplied into millions, menacing the country's agriculture.

India has a bill of rights for cows.

The only mammal with a poisonous bite is the short-tailed shrew.

The dog was the first animal to be domesticated, around 12,000 years ago.

Oysters in their natural habitat open their shells at high tide and close them at low tide. Oysters moved from Long Island Sound to tanks in Evanston, Illinois, U.S.A. (near Lake Michigan) at first opened up at the time of high tide on Long Island Sound. By a few weeks later, though, the rhythm of opening and closing had shifted until the oysters were in tune with a non-existent tide, but one that would exist if Illinois were covered by the ocean.

When the Spanish conquistadors first reached Peru, centre of the Inca empire, the Peruvian Indians felt the Spanish horses to be ferocious and deadly monsters, there being no horses native to the Americas. Through an interpreter, they asked the Spanish cavalrymen what these animals ate. In response, the Spaniards, pointing to the gold jewellery and ornaments of the Peruvians, said, "They eat those things of yellow metal. They are hungry now but do not wish to be seen eating. Leave the food in front of them and go away." The Indians gathered some gold objects for the horses. After they had left, the Spanish pocketed the gold, and then, calling back the Indians, told them that the horses were still hungry and needed more food. (source)

Over the past 2,000 years, humanity has helped to cause the extinction of about 2% of the known species of the world's mammals. (source)

To make a one-pound comb of honey, bees must collect nectar from about two million flowers.

Welwitschia mirabilis, from the deserts of Namibia, can live for over 2,000 years, yet its central trunk never grows more that 3ft in height. Instead the energy is transmitted into its two huge leaves which never fall and continue growing throughout the plant's life. The leaves can be as long as 20ft.

Perhaps the most strange annual culinary affair was hosted by Clodius, a rich Roman actor who had one hundred birds given voice lessons at a cost of approximately $250 per bird. He then had these birds made into a pie for his guests. He then offered a drink which contained a dissolved pearl worth about one-half million dollars.

The wandering albatross has the largest wing-span of any bird and can glide for six days without ever beating its wings. It can also sleep in mid-air.

When a horse rises, it straightens its front legs first; when a cow rises, it straightens its hind legs first.

The heath hen was quite commonplace in New England in the 1600s. During breeding season, it nested on the ground and would stay there, guarding its nest, even when threatened. That made them easy targets for the Puritan inhabitants of New England, who ate the bird so frequently that they grew tired of it, and the dish was relegated to servants. By 1880, the heath hen could only be found in Martha's Vineyard, off the coast of Massachusetts. By 1932 the bird was extinct. (source)

The only bird that can fly backwards is the hummingbird, which achieves this feat by beating its wings up and down at a very fast speed; some species reach 80 beats per second.

In De Rerum Natura ("On the Nature of Things"), the first-century B.C. Roman poet Lucretius wrote about how living organisms are constantly changing. He was aware of fossilized animals like none that currently exist and wrote that "Nothing remains forever what it was. Everything is on the move. Everything is transformed by nature and forced into new paths. One thing, withered by time, decays and dwindles. Another emerges from ignominy, and waxes strong." He also noted that many species must have died out in the past. (source)

The zebra is a black animal with white stripes, not a white animal with black stripes. The colouration cells in a zebra's skin are programmed to produce a black colour, and only when a genetic switch is thrown "off" that stripes without pigmentation (i.e. white bands) appear. (source)

Schenectady, New York police called to the home of 64-year-old Iva Fletcher in 1979 came across an ankle-deep swarm of cockroaches stretching from the door to the street and into the trees. The officers estimated the cockroaches numbered in the hundreds of thousands, although an exterminator later estimated the number to be in the millions. The ambulance that took Fletcher to the hospital, an animal shelter van, and four police cars all had to be fumigated after the incident. (source)

Robert Burns had a pet ewe called Poor Maillie. He wrote two poems about her.

The sea-urchin walks on the tips of its teeth.

A recording of the alarm call of Pennsylvania crows was played for French crows. It caused the crows to gather, instead of fleeing as intended.