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Why do hammerhead sharks have hammer-shaped heads?

Why do hammerhead sharks have hammer-shaped heads? – Landon, age 10

Hammerhead sharks are weird looking. They appear to be someone grabbed their skull by the attention socket and stretched their head to at least one side, while the remainder of their body looks like a standard shark.

You may be wondering – what are the advantages of getting a hammer-shaped head? And how did the hammerhead shark get that way in the primary place?

I'm one. A scientist who studies sharks. For almost 30 years. The answers to a few of these questions have surprised even me.

Advantages of Hammer

Scientists consider that hammerhead sharks have three important benefits.

The first is expounded to the sunshine of the eyes. If your eyes are pointing in two opposite directions, tell your ears, it provides you with. A very wide field of view. Each eye will see a distinct a part of the world, so that you'll have a greater sense of what's around you. But it will be hard to inform how far things are.

To accomplish this trade-off, hammerhead sharks have specialized sensory organs, called Ampullae of Lorenzini., are scattered under their hammer. These porelike organs can detect electricity.

A close-up of the bottom of a great hammerhead shark.  Its numerous sensory pores look like black dots.
If you look closely at this great hammerhead shark (), you'll be able to see the sensory opening under its hammer.
News by Alexis Rosenfeld/Getty Images via Getty Images

The burrows act essentially like a metal detector, sensing and finding prey buried beneath the sand on the ocean floor. Regular sharks even have these sense organs, but hammerheads have more. The farther these sense organs are on the prolonged head of the hammerhead, the more accurate they're in pinpointing the placement of food.

And finally, scientists consider that hammerheads help shape sharks. Sharp turns while swimming. If you've ever walked in strong winds with an umbrella or flown in an airplane, how powerful large surfaces might be in motion. If you're a hammerhead shark, and your dinner swims fast, you'll be able to turn faster than other fish to catch it.

Hammerhead Family Tree

It can be great if scientists like me could take a look at fossils and trace the event of hammerhead sharks over time. unfortunately, Hammerhead shark fossils consist almost entirely of their teeth.. This is because sharks wouldn't have bones of their bodies. Instead they're product of cartilage, which makes up your ears and nose. Cartilage breaks down much faster than teeth or bones, so it rarely fossilizes. And dental fossils tell us nothing concerning the evolution of hammerhead skulls.

Nine different species of hammerhead sharks swim within the oceans today. They vary in each size and the form of their heads. Some have heads which can be much wider than their bodies. These include the winghead shark (), great hammerhead (), smooth hammerhead (), scalloped hammerhead (), and Carolina hammerhead ().

A hammerhead shark with a round, small hammer head.
The narrowest hammerhead belongs to the bonnethead shark ().
D. Ross Robertson/Smithsonian Tropical Research Institute

Others have smaller hammers in comparison with their bodies, including the bonnethead (), scoophead shark (), small-eyed hammerhead () and scalloped bonnethead ().

Scientists have long assumed that the primary hammerhead sharks didn't have much of a hammer but, over time, some steadily evolved larger hammers. We thought that the several hammerhead sharks living today are snapshots of various periods of evolution – with small hammerheads being the oldest species within the family tree and enormous hammerheads being the most recent on the scene.

Since we don't have fossils to have a look at, scientists like myself have explored this concept using DNA. DNA is the genetic material found in cells. which comprises details about how a living thing will look and performance. It may also be used to see how living things are related.

We took DNA from eight of the nine hammerhead species and used it to have a look at the relationships between them. The results weren't what we expected. gave Older generations had proportionally larger hammers. And the younger generations had smaller hammers.

Impairments as assets

When scientists take into consideration evolution, we often assume that living things change little by little at a time, steadily adjusting themselves to raised benefit from their environment. This The process is called natural selection.. But it doesn't all the time work that way, because the evolution of the hammer head shows.

In the left diagram, the hammerhead shapes are moving from small to large.  The right diagram starts with a small hammer head, then jumps to a large hammer.  After that, the hammers become progressively smaller.
On the left is the expected evolution of hammer heads, assuming a gradual change in head shape. On the precise is the observed pattern of evolutionary change based on DNA sequence data.
Gavin Naylor, CC BY-ND

Sometimes an animal might be born with a genetic defect that is definitely useful for its survival. As long because the abnormality survives and the animal is capable of mate, the trait might be eliminated. We think that's precisely the case. What happened to the hammerhead shark?.

The first hammerhead species to branch out is the winghead shark (), which has a broad head. Over time, natural selection has actually reduced the scale of the hammer. This suggests that probably the most recent species of hammerhead is the bonnethead shark (), which has the smallest hammerhead.