What constitutes a tool use? For humans we always seem to be using tools like hammers, pencils etc. The tool use behavior has been observed in dolphins, elephants, otters, birds, primates and octopuses. While exploring Australia's Great Barrier Reef, professional diver Scott Gardner heard an odd cracking sound and swam over to investigate. What he found was a footlong blackspot tuskfish holding a clam in its mouth and whacking it against a rock. Soon the shell gave way, and the fish gobbled up the bivalve, spat out the shell fragments, and swam off. Tool use? Considering the limits of a fish to manipulate objects it may well be. Many creatures without hands have managed to use other body parts to their advantage, notably the mouth.
What constitutes a tool use? For humans we always seem to be using tools like hammers, pencils etc. The tool use behavior has been observed in dolphins, elephants, otters, birds, primates and octopuses. While exploring Australia's Great Barrier Reef, professional diver Scott Gardner heard an odd cracking sound and swam over to investigate. What he found was a footlong blackspot tuskfish holding a clam in its mouth and whacking it against a rock. Soon the shell gave way, and the fish gobbled up the bivalve, spat out the shell fragments, and swam off. Tool use? Considering the limits of a fish to manipulate objects it may well be. Many creatures without hands have managed to use other body parts to their advantage, notably the mouth.
!ADVERTISEMENT!
Tool-using fish have been few and far between, however, particularly in the wild. Archerfish target jets of water at terrestrial prey, but whether this constitutes tool use has been contentious. There have also been a handful of reports of fish cracking open hard-shelled prey, such as bivalves and sea urchins, by banging them on rocks or coral, but there's no photo or video evidence to back it up, according to Culum Brown, a behavioral ecologist at Macquarie University in Sydney, Australia.
The tuskfish caught on camera was clearly quite skilled at its task. A scattering of crushed shells around its anvil rock suggests that Gardner did not just stumble upon the fish when it got lucky. In fact, numerous such shell middens are visible around the reef. Blackspot tuskfish, members of the wrasse family, are popular food fish, so it's surprising that its shell-smashing behavior has remained unknown, Brown says.
"I absolutely loved it," says ethologist Michael Kuba of the Hebrew University of Jerusalem of the finding. Last year, Kuba and two colleagues documented stingrays in a laboratory forming jets of water with their bodies to flush food out of a pipe. But solid external objects like rocks are harder to dismiss as tools than water jets, Kuba says, and examples from the wild avoid concerns about whether a behavior elicited in the lab is "natural."
Primatologist Elisabetta Visalberghi of the Institute of Cognitive Sciences and Technologies in Rome is less convinced. Visalberghi, who documented the hammer-wielding monkeys, adheres to a stricter definition of tool use that requires the animal to hold or carry the tool itself, in this case the rock. Seagulls dropping shellfish onto hard surfaces to crack them or lab rats pushing levers to get rewards would join tuskfish in the category of proto-tool—but not true tool—users.
Scientists have observed limited groups of Bottlenose Dolphins around the Australian Pacific using a basic tool. When searching for food on the sea floor, many of these dolphins were seen tearing off pieces of sponge and wrapping them around their "bottle nose" to prevent abrasions.
Dolphins are often seen engaging in playful behavior and create tools to use for entertainment. They have been observed to blow bubbles which they form into rings to play with. After creating the bubble ring, a dolphin will use its nose and body to maintain the shape of the bubble and keep it from floating to the surface.
Elephants also show a remarkable ability to use tools, despite having no hands. Instead, they use their trunk much like one would an arm. Elephants have been observed digging holes to drink water and then ripping bark from a tree, chewing it into the shape of a ball, filling in the hole and covering over it with sand to avoid evaporation. The elephant later went back to this spot for a drink. They also often use branches to swat flies or scratch themselves. Elephants have also been known to drop very large rocks onto an electric fence to either ruin the fence or cut off the electricity.
For further information: http://news.sciencemag.org/sciencenow/2011/07/diver-snaps-first-photo-of-fish-.html?rss=1
Photo: Scott Gardner
