Long-tailed denizens of the deep (Grenadier)
Despite the fact that seas and oceans have long attracted the attention of the person as a means of communication and a source of food, until the nineteenth century, even among scientists prevailed a strong belief that at great depths there are no living beings. For example, the famous biologist Edward Forbes asserted that life is under great pressure as unthinkable, as in a vacuum.
“The last sparks of life fade on pjatisotmetrovyj depth”, — he wrote in 1840.
However, less than two decades, as we found out, many organisms live much deeper. Scientific expeditions performed in different countries in the first half of the twentieth century, showed that life penetrates even to the most extreme depths of the ocean: in 1960, the famous Explorer, Jacques Piccard, sunken bathyscaphe “Trieste” to the bottom of the Mariana trench, has found an unknown number of fish and invertebrates at a depth of about 11 km And yet for some time it was believed that, while life in the oceans exists everywhere, inhabitants of great depths is quite small. Only the results of large-scale fisheries issledovaniy–60-ies of XX century allowed to come to the conclusion that the strength of a number of fish at depths greater than 200-300 m high, they form dense clusters and can even serve as objects of hunting. One of the most characteristic and popular representatives of the demersal deep-sea fish, leading gregarious way of life, are dolgopoly . or Grenadier .
These fish are widespread from the Arctic waters of the Atlantic and Pacific oceans to Antarctica, inhabiting depths from 300 to 4000 m, but in some areas (including Pacific waters of Kamchatka and the Northern Kuril Islands) often rise to 150-200 m.
All Grenadier are distinguished by their elongated, converging on the body, which often extended in the form of thread, because of what the British call them “chrysocolla”. Tail fin as such these fish is missing. Grenadier usually uniformly colored in a grayish-brown, brown or coal-black tones.
In Kamchatkan waters of the most common and numerous three species of Grenadier — Malagasy . ash and black . The largest and most long-lived of these is the first, which size can reach 210 cm, weight — 36 kg age over 40 years, although it most often caught species in length, 60-110 cm with a mass of 1-4 kg. the other Two Grenadier are much smaller — their size usually does not exceed 60-70 cm, and body weight — 1 lbs. they form dense aggregations at depths from 400 to 1500 m.
The author is a major instance of a Grenadier
Like many other deep-sea organisms, makrousov developed a number of peculiar adaptations to life in the deep sea. On the head and along the body of these fish are huge sensitive channels opening outward fine pores, which allows them to detect prey at a considerable distance by the slightest vibrations in the water that are created by the movement of living creatures.
Unlike many other fish, which went to the depth of the eyes decrease in size and even reduced, the eyes of all the Grenadier is a very large and sometimes even huge. According to scientists, the so-developed organs of vision are the Grenadier for the detection in the deep sea luminous organisms. On the sensitivity of the visual apparatus of the Grenadier evidenced by the fact that one of these species of fish found in the Philippine Islands at depths of 500-1700 m, only 1 square millimeter of the retina, there are about 20 million light-sensitive rods.
According to modern concepts, the majority of Grenadier in adulthood leads a benthic life. Judging by the photos, they “hover” above the bottom in an inclined position, head down, examining it in search of benthic animals that serve them the food. However, some representatives of these fish consume the plankton, and therefore make vertical migrations in the water column and returning after feeding organisms. Most often the distance from the bottom does not exceed a few tens of meters, but sometimes up to 2-3 km (at the right distance from the bottom of the research vessel “Vityaz” was repeatedly caught in the Kuril-Kamchatka trench black Grenadier). The presence of well-developed swim bladder facilitates the Grenadier “soaring”.
Some experts believe that these fish are able to produce sounds that propagate for hundreds or even thousands of meters, since males of all species have a pair of powerful drum muscle, contractions which cause fluctuations of the swim bladder. Structural features of the hearing aid of the Grenadier attest to its high sensitivity. Because males and females of many species of Grenadier a significant part of the year kept separately, apparently, the ability of the latter to produce sounds facilitates mutual finding of males and females in the deep ocean during the breeding season.
Despite the fact that, according to experts, the stocks of Grenadier as off the coast of Kamchatka and in the economic zone of Russia in General quite high, so far domestic industry they operate very poorly. Although the meat of the Grenadier watered, they all belong to table fish, and therefore can be used to prepare food products. In addition, the liver of the Grenadier, as well as cod and Pollock, is characterized by high fat content and rich in vitamins.