With hundreds of species of sharks in the worlds waters, not all sharks fit the image we generally conjure up of them. There are species of sharks with adult sizes ranging between 41 feet to 6 inches, most of which are predators in one way or another. Some of these sharks have developed some pretty unusual adaptations, like the well known hammerhead shark with its horizontally extended head known as a cephalofoil. This is a list of a few more notably unique sharks.
Goblins in the Oceans!
In 2014 the capture of the rarely seen Goblin shark by a shrimper off the coast of Key West had people talking. Who wouldn’t talk about it, I mean the thing looks like something out of the mind of H.P. Lovecraft. It’s gray over a raw pink color, and when it eats it looks like someone took an orc’s face and fused it into a misshapen starving shark’s mouth to use as dentures. That knife-like projection that is the shark’s snout, is actually rather floppy. Like other sharks, and even rays and chimaeras, it does seem to have many ampullae of Lorenzini. Ampullae of Lorenzini are gel filled electro-receptors that help these types of fish detect even faint electro-magnetic fields in the water. Although the Goblin Shark (Mitsukurina owstoni) is rarely observed, it has a conservation status of “least concern”, as there is evidence that they are distributed in every ocean in the world, though they are rarely seen and even more rarely caught.
They prefer to roam the deep oceans, where the nearly red color of their skin shows up more like grey and black, effectively camouflaging them as they prowl the ocean floor hunting anything from crustaceans to squid. Watching them eat is unnerving, as their entire jaw shoots out of their mouth to grab their prey, which reminds me of the alien in Alien. Although there is at least one report of a Goblin shark being transferred to an aquarium in Tokyo in 2007[i], none have survived in captivity longer than about a week. It is postulated that it is seen more often than reported, but that observers sometimes see it as a disfigured or sick shark of another variety. The only place where the Goblin shark is regularly entangled in fishing gear is off of Southern Japan, and those are mostly juveniles. Even though there is scant information about this shy and well hidden fish, sometimes called a “living fossil” there was an incident after an earthquake in April of 2003, in which over a hundred of these elusive fish were caught off of northwestern Taiwan[ii]. The recent catch in Key West was only the second Goblin shark to be caught in the gulf.
More information is known about the male Goblin shark than the female, and the reproductive cycle has not yet been able to be studied. Despite the fact that we have never been able to study a pregnant female Goblin shark, it is likely that it shares the reproductive characteristics of mackerel sharks. Mackerel sharks are viviparous, meaning that the embryo develops inside the mother, and then is birthed, rather than the mother laying eggs that are later fertilized. They usually have smaller litters that are nourished on unfertilized eggs that remain in the uterus during gestation. So far this is just speculation and it would require further study to know for sure what their reproductive cycles involve.
The saw shark is another unusual looking denizen of the deep. It is named for its unusually flat and elongated snout with sharp teeth that stick out sideways from its mouth, making it look like some sort of demented chain saw is stuck to the front of it. There are actually nine varieties of saw sharks, most of them found off the coasts of South Africa, eastern Asia and Australia. Scientists speculate that one of the uses if this unusually structured mouth is the ability to detect the vibrations of the small fish, squid and crustaceans that it hunts along the sea floor. Once it locates its prey, it slashes at it with its saw like teeth to capture its meal.
The saw fish also hunts in the same manner as the saw shark, and at first glance looks very similar, but it is a variety of ray rather than shark. There are some very distinct differences between a saw fish and a saw shark. The saw shark is a deeper water fish hanging out somewhere around 130 feet down and below, and usually only reaches a length of five feet, whereas the saw fish can be much larger, up to 23 feet long, and tend to prefer the shallower coastlines. The gills of a saw shark are on the sides of the animal, where as the saw fish sports its gills on their undersides.
Although these guys can look a bit menacing with their rows of uneven teeth sticking out they are generally harmless to humans unless threatened.
Wobbegong or Carpet Sharks (Orectolobidae)
The Wobbegong, also known as the carpet shark, can be very hard to discern against the oceanic floor. Their mottled black and brown skin vanishes among the rocks and sand as they lay in wait along the bottom of the sea. At first glance you would think it was a catfish rather than a shark. They have more flattened body than most sharks and their dorsal fin sits farther back towards their tails, in fact the carpet shark even has the long fleshy "whiskers", called barbels, lining its face and jaw. There are several varieties of carpet shark living in shallow waters throughout the tropical regions with lengths ranging from under three feet to just over nine feet.
A Wobbegong shark hunts at night, waiting on the reef along the sea floor and propelling itself upward to snatch up its quarry. Carpet sharks are by and large docile to humans, but at up to three meters long with razor sharp teeth they might look like catfish, but they are undeniably shark, and they can become a moody and tenacious fish at times. When a Wobbegong decides to bite it has a tendency to latch on to whatever they have bitten, sometimes to their own detriment. A bite from a Wobbegong shark made headlines in October of 2014 when a carpet shark grabbed a hold of 13 year old surfer Kirra-Belle Olesson and leaving a large gash on her foot and lower leg. Fortunately the teen was able to rally and won the Australian Junior Surfing title later that December.
Video Credit: Jan Acosta 2010
Thresher Shark (Fox Shark)
There are three known species of the thresher (or fox) shark, the common thresher, the big-eye thresher and the smallest of the threshers, the pelagic thresher. Tests on the known populations of thresher shark indicate that there is at least one species of thresher shark that has so far eluded our detection. This species may well be hidden within the population of common thresher sharks, with similar appearance but very distinct genetically.
Looking at just the head and body of the thresher shark is a very traditional shark body; you might think you were looking at a tiger shark or a smallish great white type shark until you got a look at its tail. The tail of a thresher shark trails out behind it like a great pennant flag, but this tail is no mere ornamentation. This great fish uses its tail like a giant muscled whip, stunning its prey into submission. These sharks are also known for occasionally making great leaps out of the water.
Threshers are harvested by fishermen around the world for meat and large fins. The harvesting of big eye threshers is banned in the Atlantic due to concerns about their ability to withstand fishing mortality and research is being done on the ability of the common thresher to withstand current fishing patterns. The concern for their future welfare is based on the relatively slow reproduction rate of these sharks. Sexual maturity in thresher sharks is not reached until the shark is between seven and fourteen years of age and then they have only 2-4 pups per litter.