This story is over 5 years old.


What the Heck Is This Shark?

Nature is weird as hell.
Photo of the weird shark. Image: Jaime Rendon/Facebook

One of the marvelous things about the ocean is how alien it often feels to us terrestrials, especially when we come across one of the many unusual-looking species that call it home. There's no better biome than the deep blue sea to remind us just how diverse our planet's lifeforms really are.

This week, the ocean proved to us yet again that it's full of wonderful mysteries when a weird, unidentified shark was caught during a recreational fishing expedition off the coast of Los Cabos, Mexico.


According to photos from the Facebook page of Pisces Sportfishing Fleet, a luxury yacht company in Los Cabos, local fisherman Jaime Rendon was with a client aboard his boat Dr. Pescado when they hauled up a curious little shark approximately a mile offshore in 370 feet of water. After dropping a baited line, one of the men on the boat felt that he'd hooked something, and four minutes later managed to pull the unlucky creature to the surface.

"I was really surprised but what caused most impact were the eyes, so strange," Rendon told Pisces Sportfishing Fleet.

Previously in weird creatures from the deep: The Guy Who Caught the Internet's Favorite Giant Fish Is Bummed No One Gets It

Taking a look at Rendon's photos, it appears the shark could be displaying some characteristics associated with the pigmentation condition albinism. The animal's skin is a mottled pink—almost sunburnt-looking—but the majority of its body seems to be lacking any sort of pigment whatsoever. However, a close inspection of shark's face shows that its eyes are blackish-brown instead of pink or red, which is a feature that suggests it's likely leucistic, and not albino. While both albinism and leucism share a defining lack of melanin, they differ in that vertebrates with leucism will only exhibit a partial lack of pigmentation and will retain the colored cells in their eyes.

The conditions albinism and leucism aren't unheard of in sharks. Every so often, one of these animals is spotted or found washed up on a beach somewhere. But the condition is exceedingly rare in the wild, since sharks with this trait are more visible to their prey and are highly likely to be preyed upon as young.


Some other characteristics that Rendon and his fishing partner noticed about the shark were its "three rows of tiny teeth" and "three gill slits" on either side of its head.

Teeth aren't necessarily a smoking gun when it comes to shark identification—in fact, sometimes they make the whole process a lot more difficult. Shark teeth morphology depends on a host of factors such as age, sex, normal wear and tear, and even whether the row of teeth in question appear on the shark's upper or lower jaw.

Gills, while somewhat less complicated than teeth, still aren't an incredibly helpful guide when it comes to pinning the species on the mystery shark. All sharks have somewhere between 5 and 7 gill slits on each side of their head. Open ocean, or pelagic, sharks like the shortfin mako shark (Isurus oxyrinchus) need to swim continuously forward to keep oxygenated water flowing over their gills and mouth in order to breath and survive. Other sharks, such as the bottom-dwelling nurse shark (Ginglymostoma cirratum), can pump water over their gills and hang out, immobile on reefs or the ocean floor for extended periods of time. Most shark orders feature 5 gill slits, with the outlier being the Hexanchiformes order, which features 6 to 7 gill slits.

But there are no sharks that have only 3 gill slits. According to East Carolina University shark researcher Chuck Bangley, there could be an explanation for this.


"Sometimes on the more bottom-dwelling sharks some of the gill slits are smaller or really compressed together, so that may explain the weird number of gill slits. Or it could be a developmental anomaly," he told me.

When Bangley first saw photos of shark being circulated on Twitter, he tentatively identified the mysterious specimen as a swell shark (Cephaloscyllium ventriosum), suggesting that it could be albino, or unusually light-colored.

Swell sharks are a species of cat shark, and are observed off the coast of California and down through Southern Mexico, occasionally popping up in the waters off Chile. They're often found as bycatch in commercial lobster and crab traps or, in this particular case, accidentally hooked by unsuspecting fishermen.

Swell sharks in a Washington, D.C. aquarium. Image: Cliff/Wikipedia

Dr. David Ebert, director of the Pacific Shark Research Center at Moss Landing Marine Laboratories, was the first person to confirm that this was definitely a swell shark after photos were sent to him by several of his colleagues.

One of the most telling clues that the Los Cabos shark is, indeed, a swell shark, is its peculiar distended stomach (although, sometimes animals' stomachs will expand from pressure changes if they're rapidly dragged from deep ocean to the surface). According to Monterey Bay Aquarium, these small sharks are known for swallowing large amounts of sea water when threatened, so as to puff up their bellies and make them appear less of an easy meal for predators.


"The way the belly is swollen is an obviously clear sign. Most sharks can't do that. This one has the rounded snout, large semicircular mouth, and pectoral fin shape that are characteristic of swell sharks," he told me.

Dr. Ebert added that the shark was probably leucistic, as it was missing the spots and coloration that swell sharks usually exhibit. According to him, this is the first ever reported instance of leucism or albinism occurring in this particular species.

Somewhat of a "lost shark" explorer, Dr. Ebert is used to coming across fascinating finds like this. He and a fellow researcher recently discovered the ninja shark (Etmopterus benchleyi), a new species of lanternshark, off the coast of South America.

"This particular swell shark is cool to see, but with a lot of species, leucism and albinism are anomalous. In the bigger scheme of things, this discovery highlights a species that tends to be overlooked and not thought about often. Events like this encourage people to think about sharks that might not be on their radar, so I embrace them whenever they come up," he said.

There are currently 1,200 known species of sharks and skates. And twenty percent of them have been discovered in the last 10 years, Dr. Ebert told me.

Although the fishermen released the shark after catching it—in a Facebook post, Rendon said he realized he'd snagged "something special" and wanted to return it to the sea—this doesn't necessarily mean it survived to swim another day.


Ocean conservation biologist Rick MacPherson told me that "as far as catch and release fishing is concerned, it's in theory a better proposition [than killing] for sharks. But many shark species, such as hammerheads, don't do so well in catch and release scenarios. The scientific community has observed fairly high post-release mortality in these species. So it really matters how long the fish is on the hook, how much stress is built-up in the process of being landed, and then how the fish is revived after release from the hook."

But, according to MacPherson, bycatch is still a primary driver of shark mortality.

3.3 million sharks are killed each year as bycatch from longline fishing, and that just in the Pacific Ocean alone, says the World Wildlife Fund. More than 15 shark species are currently on the verge of extinction due, in part, to commercial fishing bycatch.

The intentions of the two fishermen seemed good enough, and it's pretty neat that their afternoon fishing trip landed the scientific community a fairly incredible new find. Here's hoping discoveries like this continue to inspire respect and admiration for marine ecosystems, and maybe even encourage land-dwellers to take better care of them. After all, the Earth is mostly ocean. We're just livin' around it.

Correction: This story has been corrected to reflect that shark bycatch is not the primary driver of shark mortality, but is a primary driver of shark mortality.