Look Ma, No Hands! Proving once more that it doesn’t take human abilities to use tools, scientists have documented a fish using rocks to smash open clam shells. While the ability to use tools used to be viewed as a purely human trait, researchers have shown that an assortment of animals can put objects in their environment to work, including chimpanzees, crows, and even octopuses.
The new photographs of a blackspot tuskfish in Australia’s Great Barrier Reef represent the first instance of tool use documented in fish. However, there are already some critics saying that because the fish doesn’t touch the tool (the rock) it doesn’t count as tool use. Researchers are pushing back, saying that just because the fish don’t have arms to pick up the rock doesn’t mean that it isn’t using the object to manipulate circumstances in its favor.
The pictures were taken by diver Scott Gardner who also observed many other crushed shells around the rock, which suggests that this is a systematic behavior. Research published by scientists from Macquarie University also backs up these observations. According to ecologist Culum Brown, the research will show that because the fish hit the clam against the rock with such precision, this is an activity they have long had experience doing.
Primatologist Elisabetta Visalberghi has said that the type of tool use described in the tuskfish requires little cognitively and is present in so many other species that it is often labelled proto-tool use. This is based on the fact that the object used to open the shell (the rock) is fixed on a sea floor and isn’t being moved by the fish to crack the shell open. The main argument to this is that the fish doesn’t have limbs that it can use to pick up the rock and smash it against the clam shell.
In a counter argument to Visalberghi, Brown has also said that the conditions underwater are so different from the conditions under which a primate would use tools that it wouldn’t make sense for the fish to crack the shell open by picking up the rock, even if it had the hands it would need to do so.
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