Logan Stewart of Balclutha School asks :-
Why do hammerhead sharks have heads that shape?
John Montgomery, of the University of Auckland's Leigh Marine Laboratory and School of Biological Sciences, responded.
Hammerheads help these sharks find and catch prey.
Fish (the prey for the sharks) generate electric fields. Sharks detect the electric field, and hence the prey, with sensors lodged in head pores. The hammerhead shape provides a wider head area and correspondingly more sensors than other sharks have. So, hammerheads pick up prey signals better.
The wing-like hammerhead also provides hydrodynamic lift so hammerheads can turn tighter and faster. Prey has a tougher time losing the hammerhead than other sharks.
Note that the eyes are further apart too, as are the nostrils and they this conceivably would provide some other sensory advantages.
The trouble with these speculations is that they are just that - there are no real scientific studies documenting the extent to which hammerheads may or may not be better at prey detection or capture because of their head.
One other alternate view is suggested by one observation of hammerhead sharks feeding on stingrays. The hammer-shaped head may be directly useful in prey handling. The shark used its head to `pin' a fleeing stingray against the bottom and then `pivoted' its body into position to deliver an immobilizing bite to the ray's pectoral disc.
To scientifically provide an answer to the question of the shape of a Hammerhead shark's head, one really needs to demonstrate a specific advantage that accrues from the head shape and to show that that functional advantage was instrumental in the evolution of the head shape. I think it is fair to say that we haven't met those requirements yet in providing and authoritative answer to the question.