Nov 14, 2014

The Nightmarish Shark That Lures Victims With Its Effed Up Teeth

Don’t confuse that for a smile. This shark is dead, and that’s nothing to smile about.
Not unlike Garth Brooks concerts and Applebee’s, the deep sea is one of those places you don’t need to visit to know that it sucks. Down in the depths, mates are hard to find, thus the male anglerfish bites onto a female and fuses to her body, living the rest of his bummer of a life as a gonad. In the blackness seeing is next to impossible, even with the huge eyes of, say, the giant squid. And you really never know when you’ll get your next meal, so you’d do well to have an outsized mouth to take on whatever comes your way.

It also doesn’t hurt to have row after row of backward-facing, needle-like teeth—hundreds and hundreds of them, each forked into three nasty prongs. Such is the grotesque mouth of the frilled shark, surely one of the more bizarre sharks in the sea. And it’s a mouth that biologist David A. Ebert, director of the Pacific Shark Research Center, knows all too well to respect.

“I can tell you from snagging my fingers on the teeth, you can only back out one way and that’s in toward the mouth and then out,” he said. “It didn’t feel good, I can tell you that.”

Now, science has known about the frilled shark since the 19th century, but it was Ebert who first described a second species in 2009, some 20 years after he discovered it off the coast of southern Africa. (“It happens a lot of the time,” he said nonchalantly of the delay. “You get stuck trying to go through the publishing process.”) At 3 feet long, it was about half the length of the previously known species, but no less well equipped with nasty teeth.

“Alright, Mr. DeMille. I’m ready for my closeup.
Perfect, Ebert says, for not only snagging squid, but luring them. In contrast to the shark’s dark brown or grayish skin, “the bright teeth might serve as almost a lure to bring in prey items that see this light color,” he said. “And by the time they realize, Oh, that’s the teeth of a shark, they’re too close and the shark is able to ambush them at that point.”

“It’s almost like when you drive out of a parking lot exit and they have the spikes sticking out that say, ‘Do not back up,’” he added. “That’s kind of what happens when these things catch prey items.”

As if that weren’t enough, there are extra spines that line the mouth, what are known as dermal denticles. These are scales that have been modified into pseudo-teeth—and in fact all shark teeth are scales. Incredibly, over the course of their evolution, sharks have turned scales into all manner of wonderful chompers, from the 6-inch teeth of megalodon to the frilled shark’s pronged pearly whites to the fused picket-fence-like grill of the cookiecutter shark that took a chunk out of a dude I once had the honor of interviewing.

The dermal denticles, essentially an extra set of teeth along the lips.
You may have also noticed that the shape of the frilled shark’s mouth is a bit peculiar, more like a snake’s than a shark’s. This is no accident. It’s likely an adaptation that allows the shark to gape far wider than a shark with a typical mouth orientation. (It’s worth noting that the frilled shark’s deep-sea cousin, the goblin shark, has its own lovely oral adaptation: jaws that fire so far forward they look like they’re trying to escape from its face.)

Because it has that incredible maw, the frilled shark can take prey up to half the length of its own body, including other sharks (that’s like you swallowing a person half your height, if you were looking for an analogy). Again, the better adapted you are to tackle prey of all sizes in a desolate environment, the better equipped you are to survive. “It’s kind of a contrast from, say, the white sharks, which sometimes bite and spit things out,” Ebert said. “But where they’re hunting they probably have a better chance of coming across something again.” White sharks will return to spots where the hunting is good, and while frilled sharks may do the same, there’s no doubting that their stomping grounds are far less productive than a reef ecosystem.

The frilled shark is so named for its fluffy red gills, which may help it thrive in oxygen-deprived environments. In the depths, you see, sometimes there’s enough oxygen, on account of good currents and the fact cold water more readily absorbs the gas than warm, but there often are zones where blooms of bacteria consume all the oxygen. Ebert cautions, though, that there isn’t enough data on frilled sharks to confirm that their frilly gills are an adaptation to cope with low oxygen levels.

Also a bit of a mystery is the shark’s life cycle. Critters in the deep tend to grow slowly to conserve energy because of the relative lack of food. And the frilled shark is no exception. It’s viviparous, meaning its young develop inside the mother, and according to Ebert, this can take an incredible two years (a colleague of his estimates it could be as long as three and a half years), making their gestation among the longest in the animal kingdom—the elephant’s also clocks in at about two years.

A frilled shark that goes by the name H0-34, sometimes mispronounced HO-34.
This prolonged pregnancy is an excellent strategy—if you look past the two years of weird cravings for pickles and the back pain—because the highly developed babies, as many as a dozen of them, are better suited to take on their world. “So they have larger young that are able to fend for themselves when they’re born,” said Ebert. “A lot of the bony fishes, things like salmon and stuff, they put out millions of eggs, and maybe two out of a million will survive. Whereas with the sharks and rays, they’re looking at having a much higher percentage survive.” Still, there’s an advantage in the spray-and-pray method: You can do it often, and it takes nowhere near the energy of viviparity.

Read more at Wired Science

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