Exhibition of Oceanic Hydrothermal

This part of the museum, unlike most other parts, is designed not taxonomically, but “ecologically”, so the main object of this part is not a particular taxonomic group but a community of diverse animals that constitute a very  specific ecosystem, “submerged” into the depth of the ocean. Hydrothermal ecosystem is the only ecosystem of its own kind on the Earth caused to the existence by specific planetary-scale processes taking place in the bowels of the Earth.

The vents in question are formed in the spreading zones, i.e. in the areas of slow (from 1-2 to 18-20 cm per year) moving apart of the huge blocks of the earth’s crust (tectonic plates), being moved on the outer layer of semi-liquid shell of the Earth's core (mantle). Here, the red-hot shell material (magma) is poured out, forming a young bark as a mid-ocean ridges, which total length exceeds 70,000 km.

The ocean water penetrates into the crust by cracks of the young bark to become oversaturated with minerals and heated and then returns to the ocean through the hydrothermal vents. The most hot vents with black or dark water similar superficially to the smoke are called black smokers, and more cold vents of whitish water are called white smokers.

The vents are effusions of warm (up to 30-40° C) or very hot (up to 370-400° C) water, the so-called fluid of oversaturated compounds of sulfur, iron, manganese, and some other chemical elements, and a myriad of bacteria living at the temperatures up to 110° C.

The water near these specific volcanoes is almost fresh, very acidic and rich in hydrogen sulfide. The “fireplace chimneys” of these smokers are growing onto this “liquid ore” with fantastic speed, sometimes several meters per month.

Finding of hydrothermal vents on the bottom of the World Ocean with their extremely rich and extremely exotic special fauna in 1977was one of the greatest discoveries in biology of the 20th century.

A fantastic world was opened in which ocean water in contact with the hot interior of the Earth gave rise to a very rich life. This was true oases among desert landscapes of the deep seas.

Within the first 20 years (1977-1997) of study of quite rich hydrothermal fauna, discovered were more than 450 species of animals, 97% of which  appeared to be new to science. With discovery of new vents and more detailed study of already known ones, more and more new kinds of organisms are constantly being discovered.

Biomass of the hydrothermal animal communities is 52 kg or more per square meter or 520 tons per hectare. This is 10-100 thousand times higher than the biomass of the communities on ocean floor adjacent to the mid-ocean ridges.

Stunning impression was produced by first photographs taken by submarines, which managed to capture the thickets of white tubes up to 2.5 meters long with bright red plume of tentacles prominent of them. It turned out that these giant tubes were inhabited by huge worms, previously unknown to scientists. The structure of these worms appeared to be so unusual that they were allocated to a separate class Vestimentifera within the type Pogonophora. In the largest specimens of Riftia pachyptila, the tube reaches length of 2.5 m and a wall thickness of 3 mm. In many cases, the individual tubes fused together to form a branched “trees”. The walls of the tubes are made of protein and chitin.

The front end of the worm's body bears a complex tentacular apparatus. The central tentacles are richly supplied with blood saturated with respiratory pigment hemoglobin, therefore they are bright red in color. Gas exchange is carried out through them. One of the characteristic features of Vestimentifera is a spongy tissue that occupies most of their body. This tissue, called trophosome, serves as the seat of the symbiotic bacteria that can hold more than 30% of its volume and supply their hosts with the nutrients.

Symbionts are capable of utilizing hydrogen sulfide effused by smokers in great amount. Process for producing organic compounds by means of oxidation of inorganic compounds is called chemosynthesis, which unlike photosynthesis does not require any light. They provide the oxidation of sulphides, which are toxic to all multicellulate animals. So bacteria are a key link in the entire food pyramid in the ecosystems of hydrothermal vents.

There are several rather large (up to 18-25 cm long) bivalve and gastropod mollusks living in the soil cracks and also feeding upon symbiotic bacteria. These mollusks completely lack intestines, just like vestimentifers.

The outer walls of vent craters, where the water temperature reaches about 100° C, is covered by a continuous “carpet” formed by colonial polychaete worms of the genera Alvinella and Paralvinella. These worms live in thin leathery tubes produced by themselves, but use to come out of the tubes from time to time and float around, moving away to a distance of 1 meter, where the water temperature is reduced to +2 ° C.

Numerous shrimps of the genus Rimicaris living in enormous clusters directly on the vents also feed upon bacteria settling on the shrimps’ gills. The latter totally devoid of eyes, but have a special sensory organ located on their back. This organ allows to shrimps to keep themselves within a narrow range between zone of very hot and cold waters.

There are specific predators feeding on other hydrothermal inhabitatns; these are blind white crabs of the genera Bythograea and Cyanograea. They are joined by several widespread predators of the oceanic depths, such as king crabs (Neolithodes, Paralomis) and some fish.

Discovery of hydrothermal communities showed that the Sun is, though the main, but not the only source of energy for life on Earth.

Role of hemobiosis in the life of World Ocean is still investigated insufficiently, but it is obviously very significant.

The display just described is richly illustrated with color diagrams and photographs taken in hydrothermal habitats by submarines “Mir-1” and “Mir-2”. In addition to representatives of the main members of the hydrothermal fauna, it includes two natural geological objects, the smoker’s top at the stage of its extinction and a fragment of the “chimney”. Of particular interest is a unique preparation of the giant vestimentifer, Riftia pachyptila, of about 80 cm in length.