Today’s endangered creature hails from many parts of the world’s oceans. You can find scalloped hammerhead sharks in the Atlantic Ocean, Pacific Ocean, Indian Ocean and even the Mediterranean Sea. They love coastal, warm, often shallower waters then deeper waters. Sea cliffs and continental shelves are where you’ll find them in groups the most.
The scientific name of the scalloped hammerhead is Sphyrna lewini. Don’t ask me how to pronounce that. I can only guess. I’m sure you’ve heard of hammerhead sharks before. What distinguishes them from other shark species is the “T” shape of their heads versus the long, rounded snout. Their eyes are spaced on each end of the “T” and what makes the scalloped hammerhead different from other hammerheads is the scalloped or half “U”, half moon crease that occurs on the top of their head. Their backs are usually a bronze color while their underbellies are white. They have one large dorsal fin at the front of their body but the rear fin is a lot smaller.
Scalloped hammerheads are usually solitary swimmers but they can often be found in groups especially when the food supply is abundant. Their diet consists of small fish, lobsters, crabs, small sharks and rays. Even though they have large heads, their mouths are quite small and are designed so that they can essentially swallow their prey whole instead of ripping it apart like other shark species. Scalloped hammerheads are quite friendly when it comes to humans. There have been only a handful of cases of a scalloped hammerhead biting a human; it’s just too uncharacteristic for them because they have such tiny mouths.
Female scalloped hammerheads grow to be much larger than their male counterparts. The largest scalloped hammerhead weight recorded was 336 pounds with a length of 12-14 feet. Males only grow to be about 70 pounds or so and are shorter in length. Scalloped female hammerhead sharks are viviparous which means eggs hatch inside the body, the young feed on the yolk sac of the placenta and the female gives live birth. Gestation period is about 9-10 months and pup birth occurs in the summer months in warm nursery waters such as one in Kanoehe Bay in Oahu, Hawaii. A scalloped hammerhead litter consists of about 12-38 pups and they are only about 15-18 inches long. They’ll stay in a group in those warm coastal waters until they mature and move on. Life span of a scalloped hammerhead is about 30 years.
Adult scalloped hammerhead sharks have no natural predators. Their pups are susceptible to being picked off by larger sharks or due to “disagreements” in the nest but normally they are free to swim. There are unnatural threats to the scalloped hammerhead however. Humans being the biggest threat to this species. Scalloped hammerheads are considered game fish in the commercial industry and they are often caught in bycatch (which means a fishery is fishing for a huge school of something else and the hammerhead is caught in the net as well). Their fins are used for soup, liver for vitamins, meat for general human consumption and their carcasses are used for fishmeal.
Unfortunately they have been listed as Endangered on the IUCN RedList. According to a NOAA study in 2009, scalloped hammerhead shark numbers showed that the Atlanta population decreased from 155,500 individuals in 1981 to 26,500 individuals in 2005. Quite a significant decrease and current population numbers are unknown because even though they are listed as endangered, not much has been done in the way of conservation. Hopefully more awareness will change this.
If after reading this post, you feel the need to help this beastie in some way, World Wildlife Fund has an adopt a hammerhead shark donation link here.