Almost everything about the goblin shark reflects the harshness of the dark underworld it calls home. With nutrients so hard to come by in the deep sea, energy savings have meant cutbacks in the beauty department.
The creature's muscles are flabby, its skeleton is mushy and its skin is nothing more than a thin, transparent sheath, low in both collagen and pigment. But no feature contributes to the goblin's ghoulish appearance more than its pair of extendible jaws.
How these animals use such a flexible face in the wild has been a mystery that's puzzled scientists for years. Goblin sharks can reach some 10.5 feet (3.2 metres) in length – that's no shark chart-topper, but it's impressive for an animal built for lethargy in an environment where food is scarce. Somehow, these predators eat enough to support a respectable frame.
The assumption has been that the strange fish compensate for poor swimming ability with exceptionally far reach: if you can't keep up with your prey, why not engulf it before it makes a getaway? But those suspicions weren't confirmed until 2008, when divers with Japanese broadcast company NHK managed to film a goblin shark alive in its natural habitat for the first time.
To understand just how special this bit of footage is, chew on this: fewer than 50 goblin sharks have been found in the 118 years since the first one was discovered off the Japanese coast. The animals spend their time between 130 and 4,265 feet (40-1,300 metres) beneath the surface, so most of what we know about the species to this day comes from dead specimens that have been hauled up as bycatch.
The Japanese dive team didn't just capture the predation you see above – they also managed to film four more goblin shark strikes over the following two years.
Unsurprisingly, the clips quickly made their way into programmes like Discovery Channel's "Alien Sharks", but they also caught the eye of Hokkaido University icthyologist Dr Kazuhiro Nakaya.
Nakaya and his colleagues wanted to find out more abut how the goblin shark performs its signature move, so they broke it down using frame-by-frame analysis. What they found is that the strike happens in four key phases:
Let's pretend for a moment that you're a hungry goblin shark.
1. Resting phase
This part is simple. You swim along with your mouth hanging slightly open. The trap is set; all you need is an unsuspecting morsel to swim within reach.
Unlike most deep-sea sharks, goblins have a pair of small eyes with fully functional irises that contract and dilate. They don't help much, but faint changes in light are detected as the shark lurks around. Goblins also out-schnoz Danny Devito's Penguin, and all that nasal real estate is jam-packed with electrosensory pores.
In other words, you're a deep-sea detection machine. Go on with your bad self. You're ready for step two.
2. Expansive phase
Time to open wide. Really wide.
The average human mouth opens about 50 degrees, whereas the goblin shark can manage 111 degrees without much trouble. If "human you" attempted that kind of jaw manipulation, you could rest your chin on your chest while still looking straight ahead.
Extreme skeletal movement means the goblin shark's eyeballs get jostled around a bit during each predation attempt. But you are terror. You are the deep. Stop complaining.
3. Compressive phase
Fire in the hole! Show this meal what you're made of.
With prey in reach, the goblin shark's jaws jut out, moving at a whopping 3.1 metres per second. This is by far the fastest jaw protrusion of any shark (in fact, it's faster than most cobra strikes!). Let's have a look in real time:
At maximum extension, the jaws account for as much as 9.4 percent of the shark's entire body length. To understand how crazy that is, go back to "human you" for a moment and stick your lips out as far as they can go. Now imagine them seven to ten inches farther out than you can muster.
4. Recovery phase
Here's where we enter the unknown. Once you've made your kill, you re-open and close your jaws. Why? That’s still a goblin shark secret.
This secondary action has never been observed in a shark species before, but other animals associated with extreme gapes (like snakes) have been known to "reset" this way after a big stretch.
It's also possible that the second bite ensures slippery prey like squid and fish stays locked down. Goblin shark teeth are highly recurved (pointed towards the back of the mouth), so when prey is pushed forward, it gets impaled. This is similar to how the leatherback turtle's spiked oesophagus stops jellies from making a last-minute getaway.
There's still a lot to be discovered about the life and ecology of these bizarre animals, and many unanswered questions remain that researchers like Nakaya look forward to answering in future. We still don't know where these fish reproduce, how long they live, or just how many of them are lurking in the depths. But every rare goblin sighting – and every specimen hauled in from the deep – helps us to unlock a new piece of the puzzle.
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Top header image: Dianne Bray, Museum Victoria/Wikimedia Commons
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Eerie Evolution
