selachii (&friends)

The sea toads and coffinfishes are a family of deep-sea anglerfishes.

These are bottom-dwelling fishes found on the continental slopes of the Atlantic, Indian and Pacific Oceans at depths to at least 2,460 m (8,070 ft). Of the two genera in the family, Chaunacops typically occurs at deeper depths than Chaunax, but with considerable overlap.

They have large, globose bodies and short, compressed tails, and are covered with small, spiny scales. The first dorsal fin ray is modified into a short bioluminescent lure which dangles forward over the mouth, which is turned upwards so as to be nearly vertical. The sensory canals of the lateral lines are especially conspicuous. 

🎂 Happy anniversary to Florida Keys National Marine Sanctuary! 🎉

Today, the sanctuary is 27 years old. Within this sanctuary’s 2,900 square nautical miles lie the world’s third-largest barrier reef, extensive seagrass beds, mangrove-fringed islands, and more than 6,000 species of marine life. 

Sharks have evolved to inhabit almost every part of the ocean, including the very deepest parts. 

Goblin Shark (Mitsukurina owstoni)

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The Goblin Shark is a member of the order Lamniformes, and the only living member of it’s family Mitsukurinidae. Their family has been around for ~125 million years, making the Goblin Shark a “living fossil.”  They have a long and flat snout, which gives them their “goblin-like” appearance. They have highly protrusible jaws, meaning that they can extend them forward to grasp prey.

They, like most other deepwater shark, are sluggish and move slowly. They are rarely encountered by humans, as they are found in waters greater than 100 meters. The tooth of Goblin Shark was once found stuck in an underwater cable that was over 1,300 meters below the surface. Though they’re rarely encountered, they’re thought to be quite common and abundant, inhabiting deep waters around the globe.

Unfortunately, not much is known about their behavior or reproductive biology.

They are listed as “Least Concern” by the IUCN. 

Frilled Shark (Chlamydoselachus anguineus)

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The Frilled Shark is another “living fossil” species. It’s found most often between 50 and 1,000 meters, but has been seen near the surface on rare occasions. Like the Goblin Shark, it is rarely seen but is thought to be an abundant species. 

The Frilled Shark’s teeth morphology suggests that it feeds primarily on cephalopods. It has a very wide moth gape, and can consume very large prey. This is a particularly helpful adaptation, as food is often scarce at great depths. Despite their intimidating looking jaws, they have a relatively weak bite and pose no threat to humans.

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Frilled Sharks may have the longest gestational period of any vertebrate- three and a half years. 

They are listed as “Least Concern” by the IUCN. 

Pacific Sleeper Shark (Somniosus pacificus)

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The Pacific Sleeper Shark is a member of the Sleeper Shark family Somniosidae in the order Squaliformes. It’s a large (up to 7 meters), slow-moving species that lives in waters up to 2,000 meters deep. Though they are generally sluggish, they’re thought to be both scavengers and active predators. Specimens have been found with fast moving species such as squid, harbor porpoises, and Steller’s sea lions within their stomachs, suggesting they can swim very quickly in short bursts while hunting. 

Not much is known about their life history, but they are thought to be long-lived, like their close relative the Greenland Shark.

Due to their large size, Sleeper Sharks do not have very many natural predators, though they are known to be preyed upon by orcas.

And finally, even though they’re technically not sharks, it’s time for the Shark Week shout-out to Chimaeras!

Chimaeras are often called “Ghost Sharks” but they aren’t actually sharks at all. They’re chondrichthyian relatives of sharks and rays that belong to class Holocephali. Fossil records of chimaeras date back to the Devonian period, approximately 420 million years ago.

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Chimaeras are similar to sharks in many ways, however, chimaeras swim using their pectoral fins, not caudal fins, have jaws that are fused to their skulls, and have retractable sex organs on their foreheads. Yep, you read that right. They also have no stomach, instead they have a primitive “stomach” that is fused to the intestines.

There are currently 50 known species of chimaeras.

A “Ghost Shark” Swims into Our Imaginations

To deep-sea explorers, liquid space is the final frontier, full of the weird and wonderful.

Lonny Lundsten, senior research technician at the Monterey Bay Aquarium Research Institute (MBARI), is no exception.

He was part of a team that published research about and produced a video of an unusual species of “ghost shark” in deep-sea habitat off California’s central coast—the first time the species (the pointy-nosed blue chimaera, Hydrolagus trolli) has ever been seen alive.

This animal’s unusual features probably fascinate us for the same reasons they fascinate Lonny. Its lateral line system makes it look stitched together, a little like Frankenstein’s monster. Lonny says these visible lines allow the chimaera to sense vibrations or movements in the water and likely help it find prey.

One of the male’s copulatory organs is actually located on its head. Lonny says it’s thought to be used to grasp and hold a female during copulation. Other striking features include bony tooth plates; a long, slender, pointed tail; large eyes; and large pectoral fins.

Lonny says exploring the deep sea proves the adage that truth is stranger than fiction.

“The things I see are so remarkable and startling that I don’t need to imagine what might be in the deep sea,” he says. “Carnivorous sponges are my current specialty. They are such a bizarre animal…amazing and utterly surprising!”

Exploring the deep sea is MBARI’s specialty, and its scientists have an impressive suite of technological tools at their disposal, especially a remotely operated vehicle that can descend into the ocean’s depths. Lonny conducts a lot of his research watching HD video footage of animals and habitats as filmed by the ROV.

“MBARI is using state-of-the-art technology to push into the deep sea, down to 4,000 meters. This is an environment that is largely unexplored and certainly hasn’t been filmed using high-definition video cameras,” he says. “We use specialized lighting systems and HD cameras that can resolve details down to about a millimeter in size…we can observe animal behavior, and we can see what the habitat looks like where they’re found.”

Lonny reminds us that exploring the deep sea 100 years ago was mostly done by “dragging a net through the water column or along the seafloor, basically taking a big scoop of whatever was there” and working with the pieces—often literally.

“In many cases scientists had fragments of animals, animals that had been damaged or destroyed, with colors that no longer represented how they appear in life,” he says. “Now we see these animals in their own environment, we can see their habitat, their abundance, and the other organisms that live near them. We make stunning video observations and then we can carefully collect them so they are undamaged.”

Lonny says he’s grateful that his job has made his dreams come true of discovering new species and exploring new habitats.

“The coolest thing is that I get a sense of what it must have felt like for early explorers in human history to go places nobody’s ever been and to see things that nobody’s ever seen before,” he says. “It’s truly exciting and rewards me with a feeling of awe and wonder for the natural world.”

Need more ghost shark in your life? Watch the full video! ⬇