Sunday, August 15, 1999
SEA-OTTERS, found on the Pacific coast of North America, are one of the most fascinating tool-using animals. These true marine mammals dive to the bottom of the shallow sea and bring up crabs, sea-urchins, clams, mussels and a stone on which to break open the prey. Sea urchins are the main diet of these animals, but before eating them their spines have to be removed because they are not only an obstacle in reaching the fleshy body but are also poisonous.
To do this, the otter wraps these urchins in seaweed and then breaks off the spines beneath with its paws. Once spines have been stripped off, the urchin is easy to consume.
Other shellfish, clams for example, have harder shells, and to get to the succulent flesh inside the otters has to be even more resourceful. It collects a stone of about 5 inch diameter from the seabed, and swims to the surface with the stone in a flap of skin under one armpit and the shellfish in its paw. The otter feeds whilst floating on its back. As it floats, it puts the stone on its chest and using it like an anvil smashes the shellfish against it. Once an otter has found a good stone, it carries it about, tucked under its armpit. If the otter loses the stone, it looks carefully for another one, probably rejecting several before it finally finds one that is suitable as a food-opening tool.
These mammals exclusively restricted themselves to sea and seldom go ashore not even to give birth or to sleep. While sleeping or resting they anchor themselves with long strands of kelp, a seaweed, to keep themselves from drifting away in the open ocean.
In the Galapagos islands, off the coast of Ecuador in the Pacific ocean, there are no woodpeckers, but there is another bird which has taken over the vacant niche the woodpecker finch. Being a finch and only recently (in geological terms) having found its food source, it does not have the anatomical wherewithal to exploit it. Woodpeckers have long, powerful beaks with which they can hammer into wood. They also have a specialised tongue to dislodge wood-boring grubs. The woodpecker finch has neither. Instead, it makes a tool do the job. It first visits a cactus plant and breaks off a spine. Then it takes the spine to crack or crevice in which an insect is hiding and uses it to winkle out the food.
Chimpanzees do the same with termites.To fish out these insects from their fortress chimpanzees carefully select a thin, supple twig from a branch, pulls the leaves from it and then, with great delicacy, pokes it down the narrow entrance hole of a termite mound. Very gently the chip withdraws the twig, its stem is now covered with a wriggling mass of termite soldiers, their powerful jaws gripping the "intruder". Deftly the chim pulls the stem though its lips to remove the termites and chews contentedly.
More than 30 years ago Jane Goodall, the zoologist, was amazed to discover wild chimpanzees using twigs to fish for termites. For many years the human species had identified itself as "Man the tool maker". The ability to use and manufacture tools had long been considered one of the features that set man apart from all other animal species. But ever since Jane Goodall made her momentous discovery, humans can no longer claim to be the only tool-using animals.
Since then many other examples of animals making use of tools have emerged. Wild chimpanzees have been seen using twigs as toothpicks, and leaves to wipe pus from a sore. They also chew up wads of leaves to use as sponged, which they dip into water-filled holes and suck out the moisture. To avoid being bitten by driver ants, the chimpanzees dip for them with grass stems. Researchers have even seen chimps using sticks and logs as weapons against a stuffed leopard placed in their path.
In addition, the chimpanzees tools are carefully selected and prepared. For example, a chimpanzee will smooth the twig it is going to use for termite fishing so that it will not sag as it is withdrawn from the hole and dislodge the soldier termites clinging to it.
A chimp may prepare a
fishing tool before heading for a nearby termites nest,
and carry the tool with it. This shows an intellect not
only capable of understanding a problem and solving it,
but also one able to anticipate the likely recurrence of
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