Since it is almost Halloween and kids will be knocking on doors asking for sweet handouts, it is time to start with the scary stories. Quite a few of them can be found among the animal kingdom.
No need to look far and wide for a scary monster out of your nightmares – come and meet The Black Swallower. With a name that matches its frightening description, this fish is indeed a horror of the deep sea. It is not alone in that matter. There are plenty of oddities hiding in the deep ocean.
In the twilight zone of our oceans, the ability to swallow more than you can chew is a matter of survival. This is where the Black Swallower excels. Thanks to its balloon-like stomach, huge mouth, and long lower jaw, it can swallow another fish whole. And those fish can be up to twice their length and ten times their weight.
These eating habits are similar to how snakes swallow a whole large animal. They have hooked, backward-pointing teeth which retract to make room for prey. Once caught, they interlock to keep it inside.
Black swallowers are rarely seen in their natural habitat. That is because the deeps of the ocean have not been explored thoroughly. The Black Swallowers live at around 700-3,000 meters (3,000-10,000 feet) depth. However, some dead specimens have been found floating at the ocean surface.
They were found with what looks like a semi-transparent tire hanging from their bellies, filled with barely digested larger fish. This is how their eating habits were discovered. It is always a face between digestion and gases from decomposing fish in your stomach when your eyes are bigger than your stomach. Sometimes, this is a battle that the Black Swallower loses.
When Was The Black Swallower Discovered?
In the mid 19th century, scientist J.Y. Johnson named the first specimen of the Black Swallower that was discovered. This was not a live fish but rather a carcass that floated to the surface. The scientific name of the Black Swallower is Chiasmodon niger.
Maybe it is good that these snake tooth fishes live 2.7km under the sea. At least, this means you are generally not going to see them at the surface of the water. If they were closer to the surface, they could be a danger to other species with their carnivorous eating habits.
Sometimes, if the Black Swallower fish is too greedy in their feeding, the prey fish will decompose inside their stomach before they've finished digesting it. This is how they die and allow the scientist to discover them. One species demise is another one's gain, or so the saying goes.
After their death, the Black Swallower fish float to the surface of the water. This is how the scientists know what these horrifying fish like to eat. The way they feed themselves is by locating the prey in the dark and grabbing onto its head. Their teeth prevent the prey from getting away until the Black Swallower swallows them whole. This is very efficient in the deep ocean with no light at all.
How Large Is The Black Swallower Exactly?
The black swallower or Chiasmodon niger is a part of the Chiasmodontidae family. They are also called swallowers or snake tooth fishes.
This deep ocean monster lives approximately 2.7km below the ocean surface. The zone they live in is the mesopelagic and bathypelagic zone. This means that you're unlikely to run into the Black Swallower while out for a swim.
This fish is surprisingly small. Only a few inches long with it has an abundance of sharp teeth. As much of the deep-sea fish, the Black Swallower does not grow larger than a foot, most in the six to 8-inch range. They have a long body that is compressed for its length.
The Black Swallowers are fish without any scale. Their skin is smooth and soft to the touch.
A prominent feature in the appearance of the Black Swallower is their long pectoral fins, each with about 13 rays. Their pelvic fins are small and have only five rays. This fish also has two dorsal fins. Each one is different in shape.
The dorsal fin of the Black Swallower has 12 spines. The second dorsal fin has just one spine. However, it also has about 28 soft rays. The anal fin of this fish has one spine and approximately 28 soft rays.
The feature of the Black Swallower that you will notice right away is its large stomach. This is because it evolved to eat large fish, much larger than its own body. Its mouth is lined with very sharp teeth that dig into its prey. They are hooked and prevent the prey from getting away.
With a few of their bodies floating to the surface with their prey still undigested, the scientist made a couple of estimates about the fish they eat. For example, scientists estimate that the Black Swallower can consume fish up to ten times their size and twice its length.
To help the swallowing, the lower jaw of this fish protrudes past the upper jaw. The teeth interlock when the mouth is closed, making the escape impossible. The Black Swallower also benefits from a gut that stretches to accommodate the size of the meal. The skin of the fish will become transparent. This makes it possible to see the meal inside their stomach.
Due to its eating habits, the black swallower is ideally suited for life in the deep ocean. Meals are hard to come by there. This fish has to make the most of any opportunity.
Eating Habits Of The Black Swallower
The Black Swallower fish are full predators. Their eating habits sometimes lead to their death, but it is all they can do to cope in the deep ocean.
These fish spend the majority of their time in the twilight zone - or even deeper. They have to be stealthy hunters. Its dark, scaleless body accommodates this. The Black Swallowers are very abundant in the temperate and tropical Atlantic and the Gulf of Mexico.
At only 6-8 inches long, the Black Swallower often eats fish much larger than itself. This happens with the help of an expanding stomach. Their meals are sometimes so large that there isn't enough time for digestion before it starts to decompose. Sometimes this leads to their death, but it is a risk they have to take.
When they catch their prey, the Black Swallowers clamp their teeth onto the head past the gills. Then they wait them out until they suffocate. Quite gruesome! Their teeth are designed to act as a trap that the prey cannot escape. Only once the prey has suffocated, the Black Swallower starts feeding the rest into its expanding stomach. They have a lower jaw much longer than their upper jaw, which helps with the process.
Is The Black Swallower Endangered?
Unfortunately, no one has ever seen a Black Swallower specimen alive. The only ones that the scientists are able to study are those that overeat.
Still, scientists have found eggs inside dead Black Swallowers that measure 1.1 mm. These speak about their reproductive habits. The eggs are found in fish between June to September off the coast of South Africa, which is winter in the southern hemisphere. Sometimes, juveniles are found from April to August off Bermuda.
It is currently impossible to determine how many individuals of this species are living in the ocean right now. Their range is huge, and they are not on the IUCN red list. This means that the species is not endangered. It is far from that, actually. The conditions of the Black Swallower are not changing, and since the deep ocean is rarely disturbed, their status will likely remain the same for a long time.