Sharks have evolved to inhabit almost every part of the ocean, including the very deepest parts.
Goblin Shark (Mitsukurina owstoni)
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)
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.
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)
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.
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.
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