If you wanted to know what was going on in the mind of a fish of a species short macropinnasit’s easy for you to do this - because this fish has a completely transparent head!
This species was discovered as early as 1939, but the first photos of the animal were obtained only in 2004. Malorotya macropinna lives at a great depth of about 1000 meters in the northern part of the Pacific Ocean, so it is extremely difficult to study it. And when climbing to the surface, the fish cannot withstand the pressure drop, which is why for a long time scientists could not study in detail the structure of its head. It was possible to do this only in 2008.
It turned out that the chamber filled with a clear liquid is necessary for fish to protect the eyes that are right in the head. That is, the fish literally sees through the head. And those brown dots on the transparent surface, which could initially be mistaken for sad eyes, are in fact olfactory receptors that help the small and small macropinnes to hunt.
The size of the fish is small - about 15 centimeters in length, and it feeds mainly on zooplankton, which is accumulated in large numbers on the tentacles of cnidarians - multicellular animals such as stitching. Their tentacles contain stinging cells, deadly to marine life. But the transparent shell that protects the vital organs in the fish’s head reliably protects the short-lifted macropinn from the attack of cnidarians.
How does an unusual fish move
The body is macropinnati, compressed from the sides, is small in size, and in its form resembles a torpedo or pill. The body is covered with black scales, the fins are rounded and slightly shifted to the back of the body. The structure of the body and fins is such that the fish has the ability to "hang" for a long time in one place. The same is evidenced by the weak development of muscles, which scientists attribute to vitamin D deficiency. The nature of the fish implies composure, unhurried movement, and even immobility. But in the case when Macropinna needs great speed, she presses the fins to the body and actively moves with the help of the caudal fin. When a fish develops high speed, it has a high clear-cut maneuverability, which is very important for fish that live at great depths, where prey is found, unfortunately, not often.
In connection with the habitat, and this is great depths in the waters of the Pacific Ocean, where very little light penetrates, the macropinna has the unique ability to see in pitch darkness.
Unique macropinnati eyes - help in hunting
The greatest interest are the eyes of this type of fish. They are located inside the transparent dome and are green in color, which gives them the appropriate pigment. This pigment reduces the brightness of the light by filtering it. The complex structure of the eye suggests that they play a huge role in the life of the fish. The eyes of the fish are separated by a bone septum. Scientists have concluded that macropinnas can see inside their transparent heads in different directions. While the fish swims in a horizontal direction, its tubular eyes look upwards, which allows searching for prey. Due to the fact that macropinna lives at great depths, most food objects are directly above it, and this function of the eyes becomes especially relevant.
But as soon as the macropinnas notice the prey, it assumes a vertical stance-position, which provides a “look ahead” and allows you to get food. On the head, on the front, there are false eyes, which, in fact, serve as organs of smell. Between the cylindrical eyes and the mouth there are special pockets in which various receptors are located. The transparent chamber itself is filled with a special substance that protects against adverse factors.
Interesting facts about fish with a transparent head
- This fish has the name “short-lived” not by accident: the size of the mouth is really small and, despite the fact that the macropinnas are predators, the size of the prey is rather limited: small fish, crustaceans.
- During the day, representatives of this species of fish make regular migrations to the upper layers of water in order to obtain food. At night, the fish return to the depths. The fact that representatives of this class of fish were repeatedly caught by fishermen on a small scale speaks about the ascent to the surface layers.
- In the process of reproduction, females macropinny sweep a huge number of eggs. At the beginning of the life cycle, the fry have a long body shape and are not at all like their parents. However, in the process of development, they undergo numerous morphological changes and become those adults who are so interested in scientists.
To date, scientists have identified about ten representatives of the fish of this family. Most of them live in the northern waters of the Pacific Ocean. They are quite numerous off the coast of Kamchatka, in the Sea of Okhotsk and the Bering Strait.
Representatives of the family of fish with a transparent head are represented in an aquarium located in California. This aquarium is one of the world's largest structures, and it has 93 tanks, which contain these unusual fish. This aquarium is considered one of the most visited in the world, and every year about two million people come here on tours.
Behavior and nutrition of fish
Usually these fish are stationary or move very slowly horizontally. Due to the fact that the fins are always fully stretched, the fish is in a stable position in the water, but in case of danger, it presses the fins to the body and moves with the help of sharp tail movements. They feed mainly on zooplankton of various sizes.