MY AMERICAN SCIENTIST
LOG IN! REGISTER!
SEARCH
 
RSS
Logo IMG
HOME > My Amsci > Restricted Access

How Tunas and Lamnid Sharks Swim: An Evolutionary Convergence



Restricted Access The content you've requested is available without charge only to active Sigma Xi members and American Scientist subscribers.


If you are an active member or an individual subscriber, please log in now in order to access this article.

If you are not a member or individual subscriber, you can:



Abstract:

Figure 5. Fish have two types of muscle...Click to Enlarge Image

Both tunas and lamnid sharks, including makos and whites, are top predators and have similar streamlined body shapes. And the similarity between these fishes, it turns out, is more than skin deep. The two groups have developed high-speed swimming techniques that involve efficient movements of only their tail sections, rather than the full-body undulations of most fish. They accomplish this by keeping their red muscle in their torsos and transferring the muscle force to the tail through large, specialized tendons. While the two groups' common ancestor diverged more than 400 million years ago, selection pressures seem to have made both fish hit upon nearly identical movement mechanisms.


Subscribe to American Scientist