Sharks can be really scary. But while most of us are afraid of sharks (such as the great white), few know what might be lurking in deep waters. There, at a depth of 3 thousand meters, the real monsters of the sea live - the elusive demon cat shark, deep-sea dog fish, and a ghost shark. With their strange teeth and evil eyes, they look like characters in Tim Burton films. But perhaps the creepiest fact is that we know very little about them.
A good year for researchers
To shed light on these mysterious creatures, a research expedition to the west coast of Scotland was organized in September this year. Her goal was to collect samples for a project to find out the behavior, feeding and movement of deep-sea sharks.
The expedition took two weeks and was quite difficult. The researchers collected samples at depths ranging from 500 to 2000 meters. Many scientists have previously worked in this region for a long time. Luckily for them, it has been a good year. Each day, scientists managed to obtain four to five samples, each with its own distinctive oddities.
Most of us have never seen deep sea sharks. But even though they are hidden under a layer of water that creates impenetrable darkness for the human eye, they represent a group of very diverse sharks. Looking at them, it's clear why many of these bizarre fish got their hideous names.
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The inaccessibility of the ocean depths has limited our scientific understanding of these creatures. These mysteries only enhance their complex biology.
Classification
Deep-sea sharks can be divided into three groups: katraniform, karchirin-like and chimera-like. The former include dog fish (katrans), the latter include cat sharks, and the third include ghost sharks. While katrans and cat sharks are real sharks, ghost sharks belong to the group of chimeras. They are cartilaginous fish closely related to sharks.
Features of the species
The most common family in Scottish waters is the cat shark. Researchers managed to find one of its species - the demon cat shark (Apristurus). These creatures have slender bodies with relatively large heads and narrow eyes, from which this species got its name. They are especially difficult to identify, and during the expedition, scientists encountered a species that had not previously been described. Scientists have little understanding of how many species there might be in this group, let alone their biology and ecology. They are believed to feed on shrimp, but much remains unknown.
Katrana are usually chunky, their skin resembles sandpaper. They have large eyes, and their jaws are lined with rows of teeth. In Scottish waters, scientists have managed to find a really wide variety of these fish - from a 30-centimeter Etmopteridae shark to a 1.5-meter leaf shark. Their diet is very extensive. They eat both the carcasses of whales that fall to the bottom, as well as small fish and shrimps.
Real Horror: Ecosystem Endangered
These alien-looking creatures actually make up the majority of the deep water inhabitants. About half of all sharks known to scientists live there. In addition to the ghost shark and the demon cat shark, scientists have also found a 2.5-meter sofa shark.
And while the appearance of most of these fish may scare some particularly impressionable people, the horror story of these creatures' real life is actually created by human activity. Deep sea fishing, mining and environmental pollution pose real threats to deep sea ecosystems. Given the extremely slow growth rate of these sharks, longevity and low reproductive rates, it is doubtful that these species will be able to survive in such a situation.
But without knowledge of their fundamental biology and behavior, it is very difficult to assess how much such human activity will affect them. They may not be the cutest animals on our planet, but they play an important role in the ecosystem - they store carbon dioxide and are an important link in the food chain.
Unfortunately, without appropriate conservation measures, these deep-sea ghosts and demons can become nothing more than heroes of myths and legends.
Anna Pismenna
