Bonnethead

We decided that the Hammerhead Jessee saw last Friday was actually a Bonnethead. It seemed funny to us that it was so small (other Hammerhead species can reach sizes of 12 to 20 feet!) and that she initially mistook it for a Nurse Shark. Hammerheads are one of the most distinct looking sharks you can find. So we looked through the ID book and found the Bonnethead.

From certain angles, it's understandable that a Bonnethead could be confused with other round-headed sharks. Photo from Reef Fish ID.

Bonnetheads and Hammerheads are a members of the same family, Sphyrnidae. But Bonnetheads don't get to be anywhere near the same size - usually about 2-3 feet. They also have an oddly flat shaped head like Hammerheads, but it's rounded at the front rather than broad.

Photo from: http://marinebio.org/

Photo from: http://marinebio.org/

Bonnetheads are a viviparous species, which means that it gives birth to live young. That seems like a very strange thing for a fish to do. But they don't raise or protect their young after birth. The ID book says they give birth to up to a dozen foot-long pups. The book also describes their teeth: "The front jaw teeth have narrow and erect smooth-edged cusps, those on the sides are oblique and smooth-edged, and the posterior-most teeth are broad and flat ('molar-like')." Sounds odd for a shark, I wonder what they eat.

Bonnetheads are pretty uncommon around here, so I'm super jealous I didn't get to see it. And we're both disappointed that we didn't have time to stop and watch it longer.