Fishes of the deep sea are easily the most bizarre and scary-looking marine animals. But they are also some of the most fascinating. They have developed special adaptations in order to survive on tiny food supplies and in extreme pressure. Let’s discover a world without daylight—the world of bioluminescence—with these ten incredible deep-sea fish.
Featured image credit: NOAA Ocean Exploration
Anglerfish
How deep? Some species live even deeper than 6,500 feet (2,000m)
Characteristics: Fishing pole-like dorsal spine with a light at its end protruding from the middle of the fish’s head
Credit: Open Library
The anglerfish is arguably the most famous deep-sea fish and is often depicted in ocean movies and documentaries. There are more than 200 species of anglerfish, many of which live in the midnight zone (3,300 – 13,100 feet, or 1,000 – 4,000 meters deep) of the Atlantic and Antarctic oceans.
The lure protruding from the fish’s head is tipped with esca — a sac of bioluminescent bacteria — that gives the anglerfish’s lure its characteristic glow. However, only females actually have this distinctive light.
Female anglers are ambush predators that can grow up to 4 feet. They use the bioluminescent light on their head to lure in any potential prey and to attract potential mates. Males are often as small as 8 inches (20 cm). They, in some cases, latch onto females and eventually fuse with them.
Stoplight Loosejaw
How deep? From around 1,600 to almost 13,100 feet (500 to 4,000 m)
Characteristics: The distinguishing feature of the stoplight loosejaw is its jaw which is larger than its skull and has no floor
Credit: ESRI, Dr. Beinart, Tracey T. Sutton
The stoplight loosejaw belongs to the family Stomiidae, better known as dragonfish. It has an elongated body and rounded snout with sharp fangs, which give it its dragonlike appearance. The jaw of this ambush predator hangs loose, ready to quickly snap and catch even larger prey whenever the opportunity arises.
Loosejaws can both see and produce red light, which gives them a significant advantage over other fish living in the twilight (mesopelagic) and midnight (bathypelagic) zones. It allows them to stay hidden when using the red light to look for prey, as the long wavelength red light is invisible to most other fish. Loosejaws are actually able to produce both red and green light thanks to bioluminescent organs (photophores) around their eyes — this earned them their name “stoplight.”
Chimaera
How deep? Their maximum depth is approximately 8,500 feet (2,600m), but Chimaeras are usually spotted around a depth of 1,600 feet (500m)
Characteristics: Tapering body and bulky head with a one-gill opening
Credit: NOAA Ocean Exploration
Chimaeras, also known as ghost sharks, are closely related to sharks, rays, and skates. Just like their relatives, they have skeletons that are entirely made of cartilage rather than bone.
Other similarities with sharks are their smooth, scaleless skin and the electrosensory organs chimaeras use to detect their prey. They can be found in all oceans, with the exception of the Arctic and the Antarctic.
Mariana Snailfish
How deep? Mariana snailfish live in depths from 22,600 feet (6,900 meters) to 26,830 feet (8,178 meters)
Characteristics: Short rounded body with a long tail and translucent scaleless skin
Credit: Gerringer M. E., Linley T. D., Jamieson A. J., Goetze E., Drazen J.
Mariana snailfish or Pseudoliparis Swirei holds the record for the deepest fish caught (in situ) from the ocean floor. It was collected in the Mariana Trench from 7,966 m (26,135 ft), but since then, it has been filmed in even greater depths.
In order to survive so deep, the snailfish needs to be able to withstand approximately 800 times greater pressure than the pressure at sea level. This small fish is scaleless and feeds on invertebrates, such as tiny crustaceans.
Lanternfish
How deep? Different species live at depths up to 3,300 feet (1000 meters) below the sea surface
Characteristics: A small elongated fish with large eyes can have photophores producing a blue-green light line over the body, typically on its belly, face, and tail
Credit: Edd48
Lanternfish most likely use their bioluminescence for communication and counterillumination (a form of camouflage). They undergo vertical migration, which means they move closer to the ocean surface—the epipelagic zone (10-100m or 30-300 ft.)—during the night in order to feed on their primary food source, zooplankton.
Over 240 species of lanternfish range in size anywhere from 2 to 30 cm. This small fish can be found throughout the world’s oceans. In fact, according to research, lanternfish make up 60% percent of deep-sea fish populations. This makes them essential for the marine ecosystem and leads to them becoming important prey for many larger marine animals such as other deep sea fish, tuna, salmon, jumbo squid, whales, dolphins, sharks, and others. Lanternfish are also a common target of commercial fishing.
Viperfish
How deep? From what we know, the viperfish usually remains in the twilight zone (660 – 3,300 feet or 200-1000 meters) but can be found deeper than that
Characteristics: The viperfish has two very long front fangs that stick out of the mouth and run past its eyes
Credit: jidanchaomian
Like some other deep-sea fish, viperfish also migrate during the night to shallower waters where they feed. Viperfish typically don’t get bigger than 1 foot, so they hunt primarily small crustaceans or fishes, such as lanternfish. They have long, sharp teeth, which earned them their name.
Viperfish use their bioluminescence in an interesting way. Not only do they use it to attract prey, but they also use the glowing photophores along their bellies for counterillumination. This allows them to match their background better and hide their silhouette from predators lurking below them.
Rattail Fish
How deep? Depending on the exact species, rattail can be found anywhere from 650 to around 23,000 feet (200 – 7,000m)
Characteristics: Typical rattail features are large eyes, longer pelvic fins, and a long tapering tail
Credit: NOAA Photo Library
There are hundreds of species of rattail, otherwise called Grenadier. Grenadiers are benthic fish, which means they live near the ocean floor. The depth record for rattail is 23,005 feet (7012 m).
While some species are known as apex predators, others are scavengers. Rattails eat a large variety of food, from squids and small crustaceans to other deep-sea fish.
They have a really strong sense of smell and touch. Unfortunately for Grenadiers, they are one of the deep sea fish that often gets caught with trawl nets. This is dangerous for their habitat and their numbers, as they reproduce quite slowly.
Owlfish
How deep? Anywhere from 1,800 to 22,000 ft. (550 to 6,600m)
Characteristics: Owlfishes have large owl-like eyes and can be dark brown to black in color
Credit: Free Public Domain Illustrations by rawpixel
There’s little we know about the owlfish. It is named for its large eyes resembling an owl, and it can be found in the North Pacific. The owlfish needs to take full advantage of the size of its eyes in order to see prey in the bathypelagic zone it lives in. Owlfishes are known to feed mainly on small shrimp and jellies.
Coelacanth
How deep? Typically observed in depths between 500 and 800 feet (150-240 m)
Characteristics: Paired lobe fins that resemble limbs and hard scales
Credit: Bruce A.S. Henderson
Coelacanth, or Latimeria, is often referred to as the “living fossil.” This specimen was believed to have died out together with dinosaurs until one was caught near the coast of Africa. The coelacanth is the largest fish on this list. It can grow over 6.5 feet (2 m).
Latimerias are foraging predators that feed on almost anything they can find. Scientists think that coelacanths have an electric sense that helps them find prey. From what we know, they live in deep water caves or rocky reefs of the western part of the Indian Ocean and the Indonesian waters near Sulawesi.
Deep-Sea Lizardfish
How deep? Anywhere from 2,000 to around 11,500 feet (600 to 3,500 meters), but most commonly found in depths between 3,200 and 7,000 feet (1000-2000m)
Characteristics: Flat lizard-like head that is slightly raised and a large mouth with multiple rows of sharp teeth
Credit: NOAA Ocean Exploration
Deep-sea Lizardfish (Bathysaurus Ferox) might resemble its relative shallow-water lizardfish but is, in fact, one of the top predators of the midnight zone. The deep-sea lizardfish is an ambush predator that lives on the seafloor. It is not picky; it eats basically anything that passes by, even its own kind.
The deep-sea lizardfish is a hermaphrodite, meaning it has both male and female reproductive organs. This specie has been spotted mainly throughout the Atlantic and Pacific oceans.
FAQs
How do deep-sea fish survive the pressure?
Most deep-sea fish do not have air pockets in their bodies, meaning the pressure doesn’t affect them the same as shallow-water fish. They also have a chemical called TMAO, which protects some vital proteins and molecules in their bodies from compression.
What is the deepest living deep sea fish?
The Mariana snailfish was caught at 7,966 m (26,135 ft) depth in the Mariana Trench but has been filmed in even greater depths. Mariana snailfish holds the record for the deepest fish caught in situ from the bottom of the ocean.
What is the most common fish in the deep sea?
Lanternfish make up approximately 60% of all deep-sea fish. There are more than 240 species of lanternfish, and they can be found in depths up to 1000 meters throughout the world’s oceans. Another very common deep sea fish is the rattail.
Do any fish live in the Challenger Deep?
While there are no fish known to live as deep as the bottom of challenger deep (about 36,000 feet below sea level), there are plenty of fish and other marine animals living in slightly shallower parts of the Marianna Trench. However, there are some organisms, such as marine microorganisms, shrimp, or sea cucumbers, that live in the Challenger Deep.
Do deep sea fish die/explode when brought to the surface?
It depends. In some cases, just the warmer temperatures are enough to kill the fish. Other times the gas expanding with the lower pressure can tear tissues and push on the organs (even push them out), which also results in killing the animal. However, some deep-sea organisms are able to survive as they can withstand a range of pressures.
