A shark and a discovery

I recently learned something new about a shark - the hammerhead shark, to be specific. Now, I’m not the world’s biggest shark fan. I appreciate how they are incredibly adept hunters, how they are perfectly adapted for their environments, and how they are in essential part of the balance of the earth’s oceans. But there is something a little creepy about them – their big bulging eyes, their row after row of jagged teeth, and the way they can be whipped up into a feeding frenzy with the right conditions. But of all the sharks that I know of, one of my hands-down favorites is the hammerhead. Quite frankly, I think hammerhead sharks are some of the coolest looking sharks around!

There are 9 different kinds of hammerhead sharks currently known – scalloped, great, smooth, whitefin, scalloped bonnethead, squarehead, scoophead, shovelhead and smalleye. The great hammerhead is the biggest, capable of reaching up to 20 feet long. Most of them are much smaller than this giant, though, around 10 to 11 feet long. By far their most noticeable characteristic is their heads – they all have a wide, flat head that extends out past their body to look somewhat like a flattened hammer. Their eyes and nostrils are at the tips of the extensions, allowing them to thoroughly scan the oceans for food. The different kinds of hammerheads vary in several ways, including size, distribution, and the shape of their hammers. The scalloped hammerhead has a wavy edge along the front of its head, while the smooth hammerhead has – you guessed it – a smooth edge. The great hammerhead is the largest, but has only 2 distinct bumps along the edge of its hammer. The bonnethead shark is relatively small, around 3 feet long, with a very smooth and rounded head. The smalleye hammerhead is very poorly understood. It has very small eyes relative to other hammerheads, hence the name. However, it also goes by the name golden hammerhead, because it is a really unusual golden color.

Whatever their differences, though, hammerheads all have one thing in common – their big, flat heads. It's very strange, don’t you think? What possible advantage could having a ridiculous looking head afford the shark? Well, actually, there are several advantages to it. One advantage is that it allows a very large area for the sensory organs that help it detect its prey. Called ampullae of Lorenzini, these are electrolocation sensory pores that help detect the electromagnetic fields put out by living organisms that the shark might eat. Popular prey for the hammerhead includes fish, crustaceans, and stingrays (apparently a favorite of the great hammerhead). Not only does the increased surface area for their electrolocation sensory pores help them hunt better, their nasal passages are much larger, too, giving them better smelling ability. So I already knew that. But here’s what I recently learned that I think is really neat. The hammerhead also helps the shark maneuver. The wide, flat surface of the head allows them to turn very tightly without losing stability. In addition, the head provides the shark with a lot of lift as it swims, much as a wing provides lift for a plane.

So, a wide head gives better hunting and better swimming. All in all, I'd say that's pretty smart.

Now, this may not be the most groundbreaking discovery ever – that the hammers of hammerhead sharks help them swim more efficiently. But I think there is a very important principle at work in my discovery that there was more to the hammerhead that I had previously known. There are so many things in the world that I think I know the answer to. But when I dig a little deeper, I find that there is always something new that I can learn. And that is the greatest thing about science!

The hammerhead shark picture was taken from:
http://www.sharkdiving.us/images/hammerhead/01.jpg