I assume many of you have heard about this, but a triathelete, swimming in the ocean north of San Diego, was attacked by a shark and died:



I heard that locals had noticed several seals up on the beach prior to the incident. Maybe the seals knew something predatory was in the water?

The rest of the story:

http://www.foxnews.com/story/0,2933,352694,00.html

Yep, that's about 20 miles or so from my house. Very sad for him and his family.

Man that's a terrible way to go.

Sad indeed. Man, like getting hit by lightning, you just never know.

And for sure a terrible way to go. He clearly knew what happened, but with the massive blood loss, he was probably in shock quickly, and dead on the beach.

This is a terrible incident but I hope the news media doesn't catch a sensationalist fever now and start reporting shark attacks on a daily basis like they've done before.

Do sharks see in color? Are they able to distinguish between different patterns of light and dark?

I only ask, because I wonder, since it seems like a black wetsuit makes a human look like a seal to them, what can be done? Make some zig zag yellow lightning bolt marks or something on the wetsuit? Just something so it's not black and really does look seal-like, especially when a large predator is coming up to take a bite from the bottom.

I'm sure fish scientists (my words) have studied this upside down, I just don't know what the answer is.

Interesting. I'm sitting here, holding an old shark's mouth I got during one my many Mexico trips. Many moons ago.

Anyways, it's a little one, probably no more than a foot side to side, and about half a foot top to bottom. What's interesting is the rows of teeth. Sharks have a front row of teeth, and right behind another row, and further in more rows, folded back. As they lose teeth, these row move forward.

Man, small teeth, but lots of them. Sharp SOB's and serrated on the sides. This was a little guy, but my foot would go right in there and I'd hate to think what would happen if it bit.

Crikey.

It always amazes me when I see a shark aquarium (like a few weeks ago in Ocean Park in Hong Kong), and they have a mock-up of the jaws of Carcharodon Megalodon, the "grandfather" of the Great White. 18 metres long, teeth that are 15 centimetre or longer.... an average human would only be a small snack for that one.

One thing that's interesting, to me, is that animals, predators, have no feelings about this. They just do it. It's their nature. They are hunter/killers and they do it to survive. Otherwise, they won't. But they don't agonize over it, they don't worry about the feelings of their prey. They just kill, eat, go on.

Doesn't make them bad, or evil, or anything of the sort. They are what they are. Like when the tiger attacks in the zoo, well, it's a tiger. It does what it does. We can ascribe all the human characteristics we want to animals, but in the end, they are what they are.

If you happen across a bear, or a lion, or a shark on of those days, well, you've got a problem. But it doesn't mean we run around and start shooting bears or lions or spearing sharks. That is, IMO, an overreaction, and just plain nuts. I'd rather find ways to interact them in the wild that minimizes the risk. Doesn't get rid of the risk. Hell, people jump off cliffs with para sails too. Nuts.

Not a biologist but I think colour vision, if any, is likely to be very limited in fish. Eyesight is not that important for most of them anyway (pelagic predatory species like the Great White are something of an exception though) because range is often severely restricted and without an artificial lightsource colours would be even more difficult. Ever seen a coral reef without illumination from a TV camera? It doesn't look all that colourful and infact red is an effective camouflage colour underwater!

Distinguishing patterns of light and dark (i.e. grayscale vision) - very likely yes for a predatory fish like a Great White. Colours, probably not. If the grayscale contrast of the pattern on the wet suit is good enough, the idea might still work although the attack from below strategy of the Great White complicates things (the wearer will be backlit).

OK, for those who are curious, here's my little guy trying to swallow a cell phone. Sharks do this you know. They don't discrimate between living and non living objects. They just eat it.



Now from the reverse angle, which we rarely get, unless the shark in question pariticipates:




This one did, but hey, he's been room temperature for over twenty years.

Don't know if you can see it, but the rows of teeth are there.

And after all these years, they remain sharp, I can tell you with confidence.

imagine that as a 20+foot montrosity coming for you....i'd go into total shock

Just a few minutes from my home as well.
My son and I were at that very beach last Sunday afternoon.
Quite a shock.Never heard of attacks in this area due to the warmer water.

Just a few minutes from my home as well.
My son and I were at that very beach last Sunday afternoon.
Quite a shock.Never heard of attacks in this area due to the warmer water.

Dressed in black (seal) and splashing in the water (in distress) is an invitation for a shark attack.

That the shark swam away after the attack, shows that it was not the seal in distress which the shark thought it was.

There have been several good documentaries on the TV about White sharks.

This is a Megalodon tooth that we found in a remote area on the James River in Va.
It is four inches in length and the top is chipped off so that it could be used as a spear point
by the local Powhatan Indians, the tribe that befriended the Jamestown settlers.



Here are a few more various teeth my wife and I have found over the years in the same area.



The river and the Chesapeake Bay were home to prehistoric Megalodons where they fed on whales and their calves. Not exactly a friendly place in the good old days.

Often times, these sharks are just taking a nibble to get a taste of a potential meal. Of course, that nibble is typically fatal to the prey.

Except there are generally no leisure activities where you purposely run around in a lightning storm.