Everybody, meet one of my favorite buddies from the deep: the velvet belly lantern shark, Etmopterus spinax.
(Picture credit to DeviantArt artist Polar keet)
I mean, look at that soft-looking belly. (Photo credit unknown)
Not that the shark seems mighty happen to see the light. In fact, the shark probably hates whoever is holding it right now. These sharks are the most common deepwater sharks in the northeast Atlantic, found usually at depths of 70-2,490 m (230-8,170 ft).
You know that feeling when you’re enjoying the cave-like features of your room and your mother opens up the curtains, forcing you to greet the high-noon sunlight, burning your corneas in the process? That’s probably how that little dude was feeling… times a billion. Especially with those big, large eyes.
(Photo credit unknown)
National Geographic published an article in 2013 about how these same sharks lit up their spines as a defense mechanism to ward off predators, too.
So, these already amazing predators have secret hiding powers that act like the Invisibility Cloak from Harry Potter when he’s running away from… well, everything. (Not to mention they're light-saber wielding jedi's. Coolest animal in the deep? I think so.)
Everything, it seems, except an unexpected predator who just happens to fancy dining on glowing things. Anelasma squalicola is a parasitic barnacle that feasts on shark flesh, draining nutrients as the shark swims along.
Almost like dementors, if we want to keep running with the Harry Potter analogy.
Charles Darwin, the ultimate barnacle buff (insert fangirl squeal here) noted in his 851 magnum opus that Anelasma was parasitic, yet there have been so few discovered that scientists could neither confirm nor deny his idea (science problem #47136925). Yet, have no fear, modern science is here! Scientist Henrik Glenner discovered many of these parasites… on velvet belly lantern sharks. With more victims…err, I mean, subjects… to study from, Henrik and his team discovered that Anelasma just upgraded from filter-feeders to full-fledged parasitism.
Yeah, if you don’t mind your present to look like something from outer space. I mean, these things are not pretty.
At least to me, they aren't, and I'd like to think I'm not a picky girl.
What you're seeing is two barnacles in cross-section: Analesma (left) and Lepas (right). Ci = cirri; m = mouth; pd = peduncle; r = rootlets; ma = mantle.
Credit: Rees et al, 2014, Current Biology.
Pay attention to the one on the left, especially, that's our parasitic barnacle.
Barnacles are crustaceans, just like crabs and lobsters. Most barnacles have a hard shell, yet Anelasma does not. Most barnacles have cirri (the ci in the picture) that beat water into the shell to help extract food from its surroundings. Anelasma still has their cirri… but they’re useless. Just like their useless mouth and gut.
Instead, this barnacle uses its peduncle (pd in the picture) an organ that looks like an ugly, pink caterpillar that ate too much, and then got smushed like an accordion. On Anelasma it looks like the ugly caterpillar just got hit by a speeding car and it's guts splayed out like cool branches.
This ugly caterpillar, on both barnacles, is not attached to the gut.
Yeah. Ugly, pinky caterpillar absorbs the nutrients through root-like filaments. See the caterpillar on the left? There it looks more yellow than pink.
Here you see two Analesma barnacles on the skin of a shark. The shark is part-dissected, revealing one of the barnacle's yellow peduncle.
Credit: Rees et al, 2014. Current Biology.
When looking at their DNA, these guys aren't related to those barnacles we typically see on whales. In fact, those barnacles aren't parasitic at all… they just have a case of wanderlust that whales seem to fulfill.
Nope. Instead, Anelasma’s closest relative is Capitulum mitella, a filter-feeding barnacle that lives really far away… like, in Indo-Pacific kind of far away.
Lets point a few things out, shall we:
- They’re found on coastlines. Not whales.
- Norway… Indo-Pacific… hmm. Kind of an abrupt change of environment, no? (Personally I’d choose the latter over the former but, that’s just my preference.)
And these suckers (almost literally, hahaha) are found in pairs. For loneliness or whatever?
(No, but seriously, look at those things on that poor, dead shark. It seems the story from Spongebob about that ugly barnacle that was so ugly that everybody died is sort of true!)
Credit: Irvin Kilde
One thing is for sure- this rare, parasitic barnacle has an interesting choice of food!
References: Rees, Noever, Hoeg, Ommundsen & Glenner. 2014. On the Origin of a Novel Parasitic-Feeding Mode within Suspension-Feeding Barnacles. Current Biology.