Hammerhead sharks!!

[El_Elvis_Rojo]

Does anyone know the evolutionary/functionality reason behind the shape of a hammerhead sharks head?

[ShibbOleth]

A few theories can be found here:

WHY THE HAMMER HEAD?
You probably thought, as I did, that the function of the hammerhead shark’s weirdly shaped head was to separate the eyes and thus improve binocular vision. This is not the case.
The visual fields of the hammerhead’s eyes do not overlap at all. Each eye presents the brain with a separate, completely different image to integrate.
What, then, could be the purpose of the hammer head?
No one really knows, but three suggestions are as follows:

The head acts as a hydrofoil and gives the heavier-than-water, swimbladderless shark better swimming control.
Grooves on the hammer head channel water toward the nostrils, providing “stereoscopic sniffing.”
The head is a platform for electromagnetic sensors that help locate prey. Stingrays are a favorite food of the hammerhead, and the shark may de-tect them electromagnetically, This shape of the shark’s head – wide and flattened – serves some important biological functions.
First, it adds lift which improves the shark’s swimming abilities. It also extends the shark’s sensory systems: the eyes are placed far apart, improving its vision; the ampullae of Lorenzini.
These are small pits that cover large areas of skin near the mouth and nose on the shark’s snout. They are natural electrical sensors which, at close range, can detect the weak electrical fields generated by all animals and lateral line.
The lateral line is a network of sensory hair cell clusters (neuromasts) and small water-filled canals that lie immediately beneath the skin on a shark’s head and extend along the sides of its body. This network is sensitive to external motion, and helps the shark detect prey and potential predators.

Richard Martin tells the following in his article " Why the Hammer Head? "
in Sea Frontiers 35:142, 1989 : " I have observed great hammerheads swimming close to the bottom, swinging their heads in wide arcs (a motion common, in a lesser degree, to all large sharks) as if using the increased electroreceptive area of their hammer like the sensor plate of a metal detector. Sometimes, these animals would doubleback to scoop up one of several stingrays hiding in the bottom silt. The minute electrical pulse that keeps the stingray’s heart and spiracles operating betrays their presence to a hungry hammerhead."

[stockton]

In response to ShibbOleth’s awesomely complete slamdunk post:

‘Cause they look so cool and retro?’

::New fan of Shib wanders off::