Sea otters don’t have dentists and that can be a problem! Some of their food is very hard – large sea urchins or large clams, for example. Some of us humans have broken a tooth on hard food, and it happens to otters, too.
Chris Law and his colleagues at 8 institutions in the U.S. and Canada studied the frequencies of otters’ tooth damage. They traced it further. Some otters are adept users of tools like rocks or boat hulls as anvils. They suffer less tooth damage. Otters that use tools 3/4 of the time have only 2/3 as much tooth dentine exposed in cracks, on average. They also attack larger sea urchins, getting better nutrition. Though the pattern is weak for eating crabs or snails and reverse for eating clams.
There appears to be an optimal fraction of the time to use tools. It’s 17% of the time for females and 24% of the time for males, overall. Too high tool use is related to trying to eat too much too-hard prey with lower energy to the otter per unit of effort. Also, using tools a lot can make otters such effective predators that they deplete their prey locally. You may be glad that energy-rich pizzas aren’t hard and, so far, we haven’t depleted the supply.
This has been an outreach activity of the Las Cruces Academy, viewable at GreatSchools.org
Source: Science, 17 May 2024, pp. 798-802.
