The tools animals use
Some animal groups have displayed more than 20 ways of using tools while others demonstrate just a few, scientists say.
Orangutans borrow canoes to forage for aquatic plants. Octopuses carry coconut shells to serve as shelter. Archerfish shoot water droplets from their mouths to fell insects.
Elephants have been seen draping plants and soil over the carcasses of dead peers.
These arboreal apes have been seen holding cloth or leaves in water until soaked, to make “sponges.”
Octopuses squirt water to move sand, and also maneuver shells and stones to block the entrances to their burrows.
Researchers report seeing wild capuchins placing nuts on tree trunks, and then pounding with a rock to open them.
Orangutans have been observed holding a leaf over the mouth to alter the sound of a vocalization, waving a bough to repel wasps, bending branches into a screen to hide behind, and clubbing a fish in shallow water.
Many types of birds engage in “bait fishing”—placing an insect or berry on the water’s surface, waiting nearby, and snatching the fish that’s drawn to it.
Corolla spiders affix small pebbles to the entrance of their burrows, which may help clue them into the vibrations of nearby prey.
A sand dollar’s tool use is pretty basic: Juveniles consume and retain heavy grains of sand, which act as a diver’s weight belt to hold them in place against buffeting water and sand.
Wasps use the limbs of another insect as pounding tools.
“Tool use is widespread and diverse,” says biologist Rob W. Shumaker. But it’s not necessarily a sign of intelligence. “We don’t even attempt to classify examples as thinking or not thinking,” he says.
For some animals, like the archerfish, tool use is instinctive: Each individual of the species does it, in exactly the same way. Other animals learn their skills: Before the canoeing orangutans ventured out on the water, they observed how humans used the craft.
Animals that use the most tools
Species of new world monkeys have been seen placing nuts on stone outcroppings, then pounding with a rock to open then. Orangutans have been known to repel insects by waving a bough. Bonobos may break off parts of trees and drag them noisily in the direction they want others to follow.
In the wild, gorillas use sticks to rake in items; in captivity, they copy humans’ actions such as tickling others with twigs. Baboons, members of the old world monkey subfamily, use twigs as tools to pry insects or pebbles from the ground.
Animals that use a moderate number of tools
Birds break open eggs and hard foods by dropping stones upon them. Elephants have been seen dropping rocks and logs on electric fences to break the current. The sea otter, a carnivore, strikes mollusk shells against rocks to get at the food inside. Rodents such as pocket gophers use stones as spades to dig burrows.
Gibbons in captivity have hung pieces of rope or blanket on their cages to make swings. Several insects’ larval forms attach “backpacks” of debris to their bodies as camouflage. The Australian bottlenose dolphin, a cetacean, will wear a sea sponge on its rostrum for protection when rooting around the ocean floor. Documented tool use among ungulates includes a horse scratching its side with a stick held in its mouth.
Animals that use the fewest tools
Among cephalopods’ four recorded forms of tool use: octopuses and squid hiding from threats by using their arms to scoop sand over their bodies. One of the few tool uses notes among prosimians—the most primitive of the primates—is the repositioning of a hanging vine so it could be climbed to reach food. Crustaceans have been known to pick up and carry sea anemones so they can steal food that the anemone catches.
Arachnids may put pebbles around their burrow entrance and “wire” them with silk threads that would transmit vibrations if prey approached. The carrier shell snail, a gastropod, earned its name by attaching shells and sea clutter to its own shell as protection and disguise. The extremely limited tool use by fish consists mostly of projecting water, to shoot down insects or move sand around.
SOURCE: Shumaker, R. W., Walkup, K. R., & Beck, B. B. (2011). Animal Tool Behavior: The Use and Manufacture of Tools by Animals. Johns Hopkins Press. Graphic by Alberto Lucas Lopez and Kennedy Elliott.