Fast Fish Evolved Similar Design Separately

Science - Reuters ^ | 2004-05-05 | Patricia Reaney

[Junior]

LONDON (Reuters) - Great white sharks and tuna have a similar build for speed despite evolving separately for millions of years, scientists said Wednesday.

"Nature does it best in terms of design," said Jeanine Donley of the Scripps Institution of Oceanography in California. "It is amazing that they have developed to be so similar."

Lamnid sharks, which include mako and great whites, have been separated on the evolutionary tree from bony fishes, such as tuna, for over 400 million years. But the muscles and tendons that enable them to swim so fast are remarkably similar.

"Tunas and lamnid sharks have a body form that represents an extreme in biomechanical design for high-performance swimming," Donley said.

Lamnid sharks, which inhabit tropical to cold temperate waters in almost all seas, and tuna diverged from their ancestors in the design of their swimming features millions of years ago.

Their specialized features distinguish them from nearly all other fish and make them more like each other than their closest relatives.

The team, who reported their results in the science journal Nature, used video footage of sharks swimming in a tunnel and a device that measures muscle length during movement.

They believe it was evolutionary selection that allowed them to swim at high speed with a minimum of movement.

"There are body shapes...the roundness, the degree of tapering, even the tail shape, that you can calculate what would be approximately the most efficient for steady, straight swimming or burst swimming," Donley said.

"These two types of fish have this particular type of body shape which is ideal for hydromechanical efficiency."

Commenting on the research, Adam Summers of the University of California, Irvine, said scientists have been speculating on the similarities between tuna and mako sharks for decades.

"Understanding the mechanisms behind their locomotion could lead to high-speed autonomous underwater vehicles," he added.

[Allen In Texas Hill Country]

Alright, you throw out the word 'nature' and I'll replace it with the word 'time'. It is available in infinite abundance. And if works wonders from the lowliest microbe to the merging of galaxies.

[Saturnalia]

Shark tastes nasty to matter how related to tuna it is.

[Ben Ficklin]

At one time this was called convergent evolution, as opposed to divergent evolution.

[antaresequity]

I have caught Tuna and I have caught Mako's...They are anything but similar.

The shark is a cartilaginous creature whose fins cannot articulate, and the Tuna is a bony fish whose fins not only articulate, but fold into recess' in its body.

There are so many dissimilarities with these two species its not funny.

[AndrewC]

It is available in infinite abundance.

It is not, according to some physicists. What do you get when you merge galaxies?

[null and void]

*shrug* I like it.

[Junior]

I'll take the human development cycle over the evolutionary one.

Considering the natural "development cycle" is typically fatal for those who "don't quite measure up," I can't say I blame you.

[antaresequity]

Shark tastes nasty to matter how related to tuna it is.

And they stink like crap when you cut them open.

[Junior]

Shark tastes nasty to matter how related to tuna it is.

Bite your tongue, man! If done up right, shark steak is quite tasty.

BTW, tuna is best eaten raw.

[Junior]

... I have caught Mako's...

Mako's what?

[AndrewC]

Considering the natural "development cycle" is typically fatal for those who "don't quite measure up," I can't say I blame you.

As a matter of comment, I believe the cycle is fatal for all in the naturalist viewpoint.

[Junior]

As a matter of comment, I believe the cycle is fatal for all in the naturalist viewpoint.

True, but the end comes quicker to some than others.

[AndrewC]

True, but the end comes quicker to some than others.

Yes, that is a tautology.

[Dementon]

It would be foolish to assume that the pickup truck changed due to natural selection over 75 years.

Well of course it would. Trucks don't reproduce, you silly person! ;)

[antaresequity]

Mako's what?

Mako's are like Whites...they have what ichthyologists term a 'homo circle tail'. That is the lower half of the tail fin is nearly the same length as the top half of the tail fin. I have caught and killed all types of sharks [no whites, though I have seen plenty of them], and all types of Tuna...

Inside and out...Tuna and sharks are like night and day.

The claim they are alike is like saying a black bird is like a Cessna...because they both have wings.

Mako Shark

Bluefin Tuna

[null and void]

True, but the end comes quicker to some than others. ~ Junior

Yes, that is a tautology. ~ AndrewC

The end comes to soon for us all.

That's Jethro Tull...

[AndrewC]

That's Jethro Tull...

Actually it's Moses.

Psa 90:10 The days of our years [are] threescore years and ten; and if by reason of strength [they be] fourscore years, yet [is] their strength labour and sorrow; for it is soon cut off, and we fly away.

[Trinity_Tx]

"...in the rush to divest God of any role in our affairs we have adopted a paradigm where action and purpose are ascribed to "chance".

For instance, Sproul points out that the results of a given coin toss is NOT a chance event. It is simply a physical event so complicated, and with so many uncontrolled variables, that we consider it a chance event. The reality is that it is simply an event which we have not chosen to calculate. However, we act as if "chance" acts as an agent to actively randomize the result. There is no such agent in the universe."

Honest question here... I don't understand the point, or the relevance of the second paragraph to the first.

Are you saying it would be wrong to attribute the motion and result of the coin toss to the laws of physics etc? ...That God is behind every toss of a coin, designing and guiding each coin toss event and the variables influencing it?

Couldn't one say rather, that god created the laws of physics and then the events follow accordingly?

[the_Watchman]

Couldn't one say rather, that god created the laws of physics and then the events follow accordingly?

That is precisely the correct viewpoint. However, we look on these complex events and assume that they are dictated by "chance".

In the case of a coin toss, we have chosen a sufficiently complex mechanism that we are unable to preordain or control the outcome. However, we also know that the results are equally likely in the absence of intervening control.

In the case of evolution, we observe a series of outcomes not knowing the the root cause. In the face of such obvious "design", as stated several times by the author of the post, it is ludicrous to suggest random events. After all, one would wind up with a world which looked more like Picasso's later paintings. Instead, a "process" is presumed based on random mutations with some "selection" process weeding out the "innappropriate" mutations.

Unfortunately, for this view, is the outcomes similar to this article where one has to presume parallel outcomes which are so striking. The other problem along this line is an explanation of the development of extremely complex organs such as the eye. How much variation is there really between eyes in totally different species?

[Dimensio]

It would be foolish to assume that the pickup truck changed due to natural selection over 75 years.

Of course it would. Pickup trucks don't reproduce.