Moonfish — one of the least explored fish in the world's oceans. Although it attracts attention with its appearance, it remains a mystery to researchers in the field of physiology and behavior. To date, few facts are known about her, and basically these are only superficial observations of her behavior and lifestyle. However, this fish is actively hunted.
Species origin and description
This fish got its name due to its unusual appearance, similar in shape to the moon. It is included in the order of pufferfishes and has similar teeth and skin cover from them, the absence of the outer side of the gills. For example, the poisonous puffer fish belongs to the same order, but the fugu is in the suborder of dog fish, and the moon & # 8212; in the suborder of lunates.
The order of pufferfish as a whole is very unusual. These fish are characterized by non-standard body shapes, such as a ball and a square. Fish from this order easily adapt to different water temperatures and live in almost all oceans.
Another, Latin name for this fish is mola mola, which means “millstone”, i.e. round device for warming up grain. The fish is also called “sun fish” because of its round shape. In Germany, this fish is called “head fish” because of its physiology.
The British call the moon fish “Ocean sunfish” also because of the shape of the circle and the following circumstance: this fish loves to sunbathe, floating to the surface of the water and staying there for a long time. In fact, this behavior is scientifically justified, since seagulls have a healing effect on fish – they remove parasites from under their skin with their beaks.
Moon fish is the largest representative of bony fish, since its weight can vary within a ton or even two.
Looks and Features
Usually the length of this creature is 2.5 m in height, about 2 m in length (the maximum fish grows to 4 and 3 m).
The body of the fish of the moon is laterally flattened and it is vertically elongated, which makes its appearance even more unusual. Her body can be compared in shape to a disk – a wide plane. It is also distinguished by the complete absence of a caudal fin due to underdeveloped bones of the pelvic girdle. But the fish can boast of a “pseudo-tail”, which is formed by dorsal and ventral fins shifted together. Thanks to flexible cartilaginous torches, this tail allows the fish to maneuver in the water.
An interesting fact: in 1966, a female moon fish was caught, which weighed 2300 kg. This fish got into the Guinness Book of Records.
The fish of the moon has no external gills, and its gills look like two oval holes. Because of this exposure, it often falls prey to parasites or parasitic fish. It has small eyes and a small mouth, making it harmless to most marine life.
An interesting fact: the moon fish has not only a record weight among bony fish, but also the shortest spine relative to the size of the body: only 16-18 vertebrae. Accordingly, its brain is longer than the spinal cord.
This fish does not have a swim bladder and a lateral line, thanks to which fish detect danger out of sight. The fact is due to the fact that the fish has almost no natural enemies in its habitat.
The fish is completely scaleless, and its dense skin is covered with protective mucus. However, small bony outgrowths are observed in adults, which are considered to be evolutionary “remnants” from the scales. It is not colorful – gray and brown; but in some habitats, fish are distinguished by bright patterns. In case of danger, the moon fish changes color to a darker one, which gives a frightening look in the animal kingdom.
Where does the moon fish live?
Moonfish are predisposed to living in the warm waters of any ocean, such as:
- East Pacific, namely Canada, Peru and Chile;
- Indian Ocean. Moon fish is found in any part of this ocean, including the Red Sea;
- Waters of Russia, Japan, Australia;
- Sometimes fish swim in the Baltic Sea;
- West Atlantic. Fish are rare here, appearing more often in the south of Argentina or in the Caribbean Sea.
In the east of the Atlantic (Scandinavia, South Africa);
The warmer the water, the higher the abundance of this species. For example, in the west of the Atlantic Ocean near the coasts there are about 18,000 individuals no larger than one meter in size. The only place where the moon fish does not live is the Arctic Ocean.
Fish can descend to a depth of up to 850 m. Most often they can be found at a depth of an average of 200 m, from where they occasionally float to the surface. Often the fish that surface are weak and hungry and soon die. At the same time, the water temperature should not fall below 11 degrees Celsius, as this can kill the fish.
Interesting fact: It is believed that fish float to the surface of the water not only to cleanse themselves of parasites, but also to warm body before diving to depth.
What does the moon fish eat?
Moon fish diet depends on where it lives. The food must be soft, although there have been cases that such fish ate crustaceans with hard chitin.
Moon fish usually feed on:
- Comb jellies;
- Eels and eel larvae;
- Large-sized starfish;
- Medium-sized squids. Sometimes a fight occurs between fish and squid, in which the fish, due to its low maneuverability, retreats;
- Small fish. They are more common on the surface or near reefs;
- Algae. Not the most nutritious option, so fish will eat them in case of emergency.
Such a variety of food found in the stomachs of fish suggests that the moons feed at different levels of water: both at depth and on the surface. Most often, the diet of fish of the moon is jellyfish, but they become insufficient with the rapid growth of fish.
These fish do not have the necessary maneuverability and cannot pursue prey. Therefore, their mouth is adapted to suck in a large stream of water into which food enters.
Peculiarities of character and lifestyle
Fish lead single way of life, straying into flocks only during the breeding season. However, there are fish that swim in pairs for a long period of time or even for a lifetime. Schools of fish stray only in case of accumulation of cleaner fish or gulls.
The fish spends more time at depth, occasionally surfacing to warm up the body and clean it from parasites. When she floats to the surface, she does not swim vertically, as is usually the case, but horizontally. So the area of u200bu200bher body allows seagulls to land and begin to get parasites from under the thick skin.
Unlike many fish, the fins of the moonfish do not move from side to side. The principle of their work is similar to oars: the fish rake water with them and slowly move at depth. But the fry of these fish move their not yet formed fins like ordinary fish: left and right.
Compared to many fish, the moon fish swims very slowly. The maximum speed of movement is about 3 km/h, but the fish cover relatively long distances: up to 26 km per day. This is due to the fact that the vertical shape of the fish allows you to catch currents that accelerate its movement.
By nature, these fish are phlegmatic. They do not show aggression to the surrounding life forms and are absolutely harmless to humans. Despite its impressive size, the moon fish freely allows scuba divers to swim in close proximity with them. In the event of an attack, the moon fish is not able to fight back, because it does not have the necessary dexterity, and its jaws are not adapted to cracking through solid objects.
Social structure and reproduction
How It has already been said that in the bulk of the fish of the moon – loners. Due to the fact that this species is poorly understood, it is difficult to say exactly about the biology of reproduction. But scientists have found that the moon fish is the most prolific vertebrate on the planet.
The mating season falls roughly on the summer period of time, when the fish have the opportunity to go to shallow water. This is a rare case when you can see a flock of fish. Due to the fact that the fish are together in a small space, they often spawn in the same place. This is where the parental role of the fish of the moon ends.
An adult fish lays up to 300 million eggs, from which larvae appear. The larvae have a pinhead size of 2.5 mm and have a protective sheath in the form of a translucent film. In the state of the larva, the moon fish has an outward resemblance to a relative – the puffer fish. Only the appearance factor is a protection for the larvae, since otherwise they are not protected by anything from predators and an aggressive external environment.
Moon fish lays eggs in the southern part of the Atlantic waters, the Indian and Pacific oceans. In their natural habitat, moon fish live up to 23 years, rarely reaching 27. In captivity, fish grow quickly and reach large sizes, but their life expectancy is reduced to 10 years.
Because fish the moon lives mainly in deep waters, it has few natural enemies.
- Sea lions. Often this predator cannot bite through the thick skin of the fish of the moon. He catches her when she is on the surface and bites off her fins, making it impossible to move. If further attempts to bite through the fish are not successful, the sea lion leaves the prey in this state, after which the fish drowns and is left to be eaten by starfish.
- Orcas. Fish-eating killer whales attack the moonfish, but cases are quite rare. Often cetaceans have no interest in this species and ignore it. The killer whales that attacked the moonfish were hungry or old for a full-fledged hunt.
- Sharks. These predators willingly attack moon fish. The jaws of sharks allow you to freely bite through the thick skin of fish, and the remains go to underwater scavengers – small crustaceans and starfish. But sharks aren't often at the depths of the fish of the moon, so these skirmishes are rare.
- The main enemy for the fish of the moon is man. Not so long ago, fishing for this species was very popular, although the fish itself carries very little nutritional value. They got it as a trophy, because not so long ago the moon fish was a mysterious and unexplored inhabitant of the ocean.
Population and species status
It is difficult to estimate the approximate number of moonfish in the world. It is prolific and has almost no natural enemies, so you can not worry about the population of this species. Ocean pollution is one of the few dangers to fish. Often, along with food, they suck in plastic waste, which clogs the respiratory tract and causes suffocation.
Despite the fact that the moon fish is absolutely not an aggressive creature, sometimes it collides with boats or jumps into them which sometimes led to injuries and accidents. Such collisions are very common.
There is still an active fishery for this fish. Their meat is not tasty, nutritious and healthy, but is considered a delicacy in Eastern countries. All parts of the fish are eaten, including the internal organs (some are even prescribed healing properties). The moon fish continues to be explored by scientists. The priority at the moment is the study of migration processes and reproduction features.