I’ve been terrified of sharks for as long as I can remember. It started when I saw the movie poster for Jaws:
Look at the lady, swimming along as if she had no care in the world!
She is completely oblivious to the horrific monster below her!
My thought processes as a child seeing this poster: Who knows what lurks in the depths of the ocean?! Or in the depths of any body of water that is deeper than my own height?! Including lakes, rivers, and…swimming pools?!
And so began my paranoia of swimming and my insistence that I’ll-just-stay-on-the-beach-and-build-sand-castles-because-that’s-what-I-like-best.
I’m happy to say that I’m better now. I will swim in pools. And lakes, and rivers. Even oceans. But there will still be some degree of stress hormones flowing through my circulatory system. Closing my eyes under water is when the Jaws poster and what it implies comes rushing back to haunt me. Visions like this:
Anyway, instead of simply hating sharks, over the years I’ve developed a certain respect for them. It comes from learning that:
- They are at the very top of the food chain. Gotta give props for that.
- They do not hunt and seek human flesh. If they see a human, they might be curious. With no hands to use to reach out and touch, all they have is their mouth. Unfortunately, with the strength of their jaws and their razor-sharp teeth, a small “test bite” is enough to kill or at least significantly harm a human.
- Sharks have been around for millions of years. Quite a feat of evolution if you ask me.
I was bored during a meeting the other day so I perused the recent table of contents for the journal Behavioral Ecology & Sociobiology. I found a study on great white sharks. What caught my eye is that there aren’t many studies on the social behaviour of great white sharks that I know of, and this study was looking to see whether great white sharks are social creatures (i.e., do they hang out with other great white sharks?) or if they are loners.
The researchers lured great white sharks off the coast of South Africa using chum and tuna heads (blech!). When they surfaced they took photographs of their dorsal fin in order to identify them. (Apparently there can be different markings and scars and stuff on their fins.) They identified 323 individual sharks. That’s a lot of time spent on a boat surrounded by a churning mass of sharks!
As the sharks were feeding, the researchers watched to see whether there were any patterns in their movements. Specifically, they watched whether sharks hung around specific sharks or whether they just swam around other sharks at random.
They found that, overall, sharks pretty much congregated around the chum at random. That is, sharks didn’t seem to hang out with any other particular sharks. The researchers did discover, however, that sharks of the same sex and similar size tended to group together. Here is a really cool way that they graphed their results:
This study suggests that white sharks are quite solitary, even when they are in a situation with a lot of other sharks. But who knows if, or what, they might be communicating with each other, regardless of not “hanging out” together? White sharks do have rather big brains, as the authors of the study point out, but maybe a lot (or most) of that brain tissue is devoted to catching prey that is constantly on the move.
Hopefully, with the evolution of technology, we can eventually study the behaviour of these big, mysterious animals in more depth. Despite how scary they are, they are quite fascinating.
Two things before I sign off:
- Three of the researchers of the study are affiliated with Dalhousie University in Canada! Woo-hoo!
- Here is a somewhat less scary picture of a shark:
Findlay, R., Gennari, E., Cantor, M., & Tittensor, D. P. (2016). How solitary are white sharks: social interactions or just spatial proximity? Behavioral Ecology & Sociobiology, 70, 1735-1744.