Sharks inhabit every ocean around the globe, and despite most people not living near the ocean, many have likely heard of great white sharks and tiger sharks. While these well-known sharks are major predators, they tend to stay in shallower waters.
There are some sharks, however, that swim so deep in the ocean that people know little about these predators. In recent years, technology has helped scientists better understand deep-sea sharks. Learn more about them here with these four sharks that swim deep beneath the surface.
1. Scalloped Hammerhead Sharks (Sphyrna lewini)
Preferred Waters: Warmer coastal areas
Known Depths: 2,600 feet
The scalloped hammerhead sharks are named for the rounded curves that run across their wide, hammer-shaped heads. They prefer warm, coastal waters and have been seen as north as New Jersey and as far south as Australia.
In a May 2023 article in Science, researchers revealed the scalloped hammerhead is a deep-sea shark that can dive past 800 meters (or 2,600 feet) when hunting. They do so by closing their gills and holding their breath to prevent heat transfer when they enter the chilly waters of the deep sea.
Hammerhead sharks are threatened by overfishing, and they are critically endangered. Shark-fin hunters have targeted them and constitute as much as 5 percent of the commercial shark trade. And because they swim near coastal waters, they often come into contact with human populations and have been involved in bite incidents. If provoked, they are considered potentially dangerous sharks.
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2. Goblin Sharks (Mitsukurina owstoni)
Preferred waters: Observed in coastal areas worldwide from the Gulf of Mexico to Japan
Known Depths: 4,200 feet
The goblin shark is a rare, elusive shark that gives off a serious pre-historic vibe. One research team described it as having a “flabby body” and “flat, blade-like elongated snout, tiny eyes.”
Given that the goblin shark likes to keep to itself, researchers have long wondered about its feeding behavior and how it survives in the ocean deep. In a 2016 study in Nature, researchers were able to video these sharks for the first time and gain an understanding of how their jaws have adapted for them to thrive in deep seas where food is scarcer.
After analyzing videos of the goblin shark feeding, researchers have suggested it is likely a “ram feeder.” Its jaws protrude during feeding, meaning it swims with its mouth open to catch food. The lower jaw has more movement and can “capture and manipulate” prey.
Scientists have found various deep-sea creatures inside goblin sharks’ stomachs, including bony fish. Researchers think the goblin shark evolved to have this unique jaw structure in order to compensate for being a relatively slow swimmer and for inhabiting great depths where there is less food.
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3. Whale shark (Rhincodon typus)
Preferred waters: Tropical Seas, ranging from Mexico to the Philippines
Known Depths: 6,500 feet
The surface-level behavior of whale sharks has been well-documented by researchers. Scientists have seen whale sharks interacting with bottle-nose dolphins, and the dolphins seem to enjoy swimming in the wakes made by these giant, docile creatures. Researchers have also seen requiem sharks rubbing against whale sharks, which makes scientists suspect this might be a mutually beneficial behavior that helps both creatures remove unwanted parasites.
Only recently have researchers learned more about whale sharks’ deep sea dives. Although they are known to surface feed, they can go to depths of 2,000 meters (6,500 feet) in their hunt for food.
A February 2023 report in PNAS found a mutation that causes night blindness in humans is also seen in whale sharks. This mutation enables them to see at deep, dark depths where only blue light filters in.
Whale sharks are ram feeders that swim with open mouths to feast on plankton and small oceanic creatures. This unfussy approach to mealtime means whale sharks are now vulnerable to swallowing plastics and other human refuse tossed in the ocean. Their populations are declining due to overfishing, and they are considered endangered.
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4. Pacific Sleeper Shark (Somniosus pacificus)
Preferred waters: Pacific coasts, including California to Alaska, China and Russian Federation
Known Depths: 6,500 feet
Depending on where in the world a Pacific sleeper shark is swimming, it might never come to the surface. At higher latitudes, sleeper sharks can be found in shallower waters. But in lower latitudes near California or Baja, they stay exclusively in deep waters, around 2,000 meters (6,500 feet).
The Pacific sleeper shark is both a predator and a scavenger. As a predator, the Pacific sleeper shark is able to swim quietly and ambush unsuspecting prey. They have been known to eat squid, crabs, octopuses and harbor seals. Like many deep-sea dwellers, the Pacific sleeper shark is on the sluggish side, and it is not known for being able to catch fast-swimming salmon or seals.
Most of the Pacific sleeper sharks’ movements happen vertically, and most of their time is spent swimming from deep to shallow water and then back again.
A 2006 study in the Journal of Fish Biology used radio telemetry to monitor the motions of tagged Pacific sleeper sharks in the Gulf of Alaska. To the scientists’ surprise, the sharks were almost always swimming vertically. They tended to go deeper during the day and up to shallower waters at night.
With all their vertical swimming, pacific sleeper sharks kept a close range. The researchers in the study tagged the sharks in August, and the following spring found that 76 percent were within 62 miles of where they were released the previous summer.
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