In honor of the world premier of David Shiffman’s first major motion picture, “Four things everyone needs to know about sharks,” we are proud to repost our original response to the article, “Sharks are sub-par, at best.” Enjoy!
For too long have I sat idly by as my co-blogger has waxed poetic on the glories of sharks. How great they are as predators, how perfectly they’ve evolved. They’re ancient, pre-historic, haven’t changed in millions of years. They’re the ultimate predator, and champion in the ocean. Unchallenged, unmatched, awesome. A wonder of evolution.
It’s time to clear up some of those -other- myths about sharks.
The fearsome whorl-toothed shark
1. Sharks are ancient creatures that have lived unchanged for millions of years.
While technically true that sub-class Elasmobranchii has been around for hundreds of millions of years, modern sharks are, well, modern. They’ve been evolving for exactly as much time as just about everything else currently alive. And they are far from unchanged. Modern sharks, though they may resemble some older models (just like modern lemurs resemble Ida), are much different beasts then their Silurian cousins. Ancient sharks occured in a diversity of forms, back when they actually dominated the ocean. These modern sharks are just the scruffy leftovers.
The other part of this equation is that while some elasmobranchs retained their primitive characteristics through present time, the most successful ones did not. These are the elsmobranchs that are the common ancestors of modern bony fish, modern tetrapods, modern primates. Yeah, some sharks stayed sharks, but the common ancestor of nearly all vertebrates was some kind of elasmobranch.
2. Sharks are marvels of evolution, perfectly adapted to their environment.
Well, no, not really. Not at all actually. As with everything that evolves, sharks are a fairly sub-optimal design. They’re bad at regulating heat, removing waste, they’re very energy inefficient. But much much worse than that, modern sharks are bad at evolution. They are slow reproducers with small brood sizes. There is low genetic variability between generations. All that builds up to the fact that sharks can’t quickly adapt to changes in their environment. Mammals can. Arthropods do it better than anything. Sharks benefit from a wide range of tolerances, but populations can’t survive rapid environmental change, like, say, ocean acidification or over-fishing. But that’s all just semantics, because there’s no such thing as a perfect predator, just one that’s ideal for the environment it’s in. And sharks are pretty good, but not perfect.
Don't mess with inverts
3. Sharks can smell a drop of blood miles away.
Ok, this on has always seemed pretty silly, and has nothing to do with sharks and everything to do with how little people tend to know about chemistry or physiology. You can’t smell a molecule of anything from any distance. You can only detect molecules that are sitting on whatever sensor you use to sense them.
Sharks can detect an incredibly dilute molecule in the water. But if you drop a bucket of chum overboard, they’re not going to immediately know several miles away, you’ll have to wait until the chemical cues reach them. That’s not very impressive. Most animals have a range of chemical cues they can pick up on in incredibly low dilutions.
4. Sharks are the ultimate predator in the ocean.
There’s a whole mess of different ways to be a predator, and sharks are fairly dull. They don’t have venom, adaptive camouflage, they don’t regularly fight giant squid or snipe insects out of the air. They don’t have sonar, radar, infrared. All they’ve got going for them is their electrosensitivity, which puts them on par with that most fearsome of creatures, the duck-billed platypus. Oh noes! Not the platypus, I’m quaking in my wetsuit.
Oh, wait, platypuses have venom. I guess sharks lose to them, too.
~Southern Fried Scientist
We need sharks more than they need us, that’s for sure. The human species is single-handedly responsible for bringing them down to near-extinction; how great is that? I think sharks are a lot better than we are, know what I mean?
While I appreciate the support, I don’t think that claiming that sharks are “better” than people is terribly helpful to the cause.
I think we can (and should) argue that humans are better off with sharks than we are without sharks.
I don’t think we can (or should) argue that sharks are more important or better than people
With respect to your opinion, Fallopia Tuba, I think the need for each other is completely mutual. Without us helping them, they can not help us. Everything on Earth plays a role in the environment. We help where we can because we are far more evolved, and let nature take care of the rest. Earth is one big family, everyone needs everyone.
Well here is everything you need to know about an idiot who can type.1 He has the old school info and is very out of date.2 Sharks have been here for 400 million years.3 Humans are the top preditor now driving the sharks to extintion, no catch limit. no protection. 90% of their populations are dead. The evidence is in wharehouses in Hong Kong to make shark fin soup and they throw away the mutilated catch in the sea. It’s amutibillion dollar industry. You think Sharks are lame!They are on the brink of extintion on your watch.This is all you can say about them. LOOK IN THE MIRROR.Did you get you facts from the SCI FI movie Jaws! you are out of date my friend.
comic books never lie
But of course, you should actually read something before you post on it, since all of your complaints are dead wrong. I’m fairly confident you have no idea what your talking about, especially since our resident shark biologist is in total grudging agreement with those facts.
If you were paying attention you might realize that everything up there – highly basal characteristics, sub-optimal design, low reproductive rates, lack of predator induced selection – are all reason why sharks need to protected. The very fact that at best, sharks are sub-par, is why they’re in trouble and need protection. If they were perfect, they wouldn’t need our help.
“If they were perfect, they wouldn’t need our help.”
I really like this point.
A causes B
B causes C
therefore
A causes C
A = “sharks are sub-par”
B = “sharks need protection”
C = “David agrees with point”
Thus, David agrees that sharks are sub-par. Freshman philosophy for the win!
I agree that sharks aren’t evolutionary novel in their hunting strategies, that they can’t actually detect blood remotely, that they aren’t capable of evolving rapidly to changes in their environment, and that they need protection.
Once again, though, I don’t care that they aren’t evolutionary novel in their hunting strategies. What matters to me is that they are ecologically important and declining in population.
Deep Sea News has something to say about that: http://deepseanews.com/2010/03/batman-lightsaber-shark/
Batman is totally evolutionary novel in his hunting strategy.
Lightsabers are from “a long time ago” in a galaxy far far away. They’ve been used before in the distant past.
If sharks were perfect, they would be able to regrow their fins in quick time once thrown back into the sea, or be able to dissolve nets with some sort of secretion activated when trapped.
If tigers were perfect, they would have crap ugly fur. If elephants were perfect, they would grow their tusks from something cheap and unwanted. Etc etc….
To argue that an animal is sub-par because it hasn’t evolved ways to protect itself from the wants and mass methods of humans is a bit steep. A bit sub-par. 😉
I am intrigued by many of your other comments though!
“Sharks can smell a drop of blood from miles away” I have always wondered about this, especially in the movie ‘Finding Nemo’ It’s alway interesting to me why the movies always make sharks seem so horrible and bad. The movie Jaws, which I watched when I was about 8, has scared me so much, I still don’t like sharks. As far as Sharks being labeled as the ultimate predator, just because of their size, electrosensitivity and power is pretty impressive.
I wonder what Sharks will look like in a few hundred years, and what they will evolve into.