Date: September 8, 2016
Source: University of Washington
Sharks have a big reputation for
their teeth. The ocean predators use their buzz saw mouths to efficiently
dismantle prey, ranging from marine mammals and sea turtles to seabirds and --
as Hollywood likes to remind us -- an occasional human.
There are more than 400 species
of sharks in the world and each has a unique tooth shape. Some are simple
triangles, while others are deeply notched or spear-shaped. But despite this
variety, scientists haven't detected a difference in how different shark teeth
cut and poke tissue.
A recent University of Washington
study sought to understand why shark teeth are shaped differently and what
biological advantages various shapes have by testing their performance under
realistic conditions. The results appeared in August in the journal Royal
Society Open Science.
"When you have all these
different tooth shapes, there should be some functional reason. That issue was
fundamentally troubling to me," said senior author Adam Summers, a UW
professor of biology and of aquatic and fishery sciences. "It seemed
likely what we were missing is that sharks move when they eat."
Sharks shake their heads rapidly
when they bite their prey, so evaluating how teeth perform while in a
side-to-side motion was critical to the study tests, which took place during a
summer marine biology course at the UW's Friday Harbor Laboratories on San Juan
Island.
Summers and his collaborators
affixed three different types of shark teeth to the blade of a reciprocating
power saw, then cut through thick slices of Alaska chum salmon at a speed that
mimicked the velocity of head-shaking as a shark devours its prey.
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