Thursday, March 19, 2009

Bioluminescent Under the Arctic Abyss

Bioluminescence is the production and emission of light by a living organism as the result of a chemical reaction during which chemical energy is converted to light energy. Its name is a hybrid word, originating from the Greek bios for "living" and the Latin lumen "light". Adenosine triphosphate is involved in most instances.


The chemical reaction can occur either inside or outside the cell. In bacteria, the expression of genes related to bioluminescence is controlled by an operon called the Lux operon. Bioluminescence has appeared independently several times during evolution.

Bioluminescence occurs in marine vertebrates and invertebrates, as well as microorganisms and terrestrial animals. Symbiotic organisms carried within larger organisms are also known to bioluminesce.

Some of Bioluminescent creatures give off light continually. Others flash their lights on and off by mixing their chemicals on queue or by covering their light organs with a flap of skin. The flashlight fish has a light-producing organ near its eyes that is covered with an eyelid-type flap. The fish can flash its light by opening and closing this flap. These creatures produce light for a variety of reasons. For some, it is a warning to stay away. For others, it is a form of camouflage. Certain species of shallow water squid give off light to blend in with the moonlight. Some creatures use their light for navigation.

Certain fish species use bioluminescence as a form of "night light". Some use it for communication. Certain species of crustaceans send out coded signals to others of their own kind during mating season. Other creatures use bioluminescence as a trap. The anglerfish uses a lighted "lure" on the top of its head to attract its prey. When the unsuspecting animal is within striking distance, the angler vacuums it down with a lightening-fast snap of its powerful jaws. Whatever the reason for producing this dazzling light show, it remains as one of the natural world's most bizarre and spectacular facts.


Saturday, March 14, 2009

Lake Baikal - The Pearl of Siberia

The border between Siberian Russia and Mongolia is a natural divide here, with rugged hills and mountains forming series of wrinkles between the sprawling Russian forests to the north and rolling grasslands to the south. About midway along this border, in a gigantic stone bowl nearly four hundred miles (636 km) long and almost fifty miles (80 km) wide, lies almost one quarter of the all the fresh water on earth--Lake Baikal.

Lake Baikal

At 1,637 meters (5,370 ft), Lake Baikal is the deepest lake in the world and the largest freshwater lake in the world by volume. However, Lake Baikal contains less than one third the amount of water as the Caspian Sea, which is the largest lake in the world. Like Lake Tanganyika, Lake Baikal was formed in an ancient rift valley and therefore, is long and crescent-shaped with a surface area (31,494 km2/12,160 sq mi), less than that of Lake Superior or Lake Victoria. Baikal is home to more than 1,700 species of plants and animals, two thirds of which can be found nowhere else in the world and was declared a UNESCO World Heritage Site in 1996. At more than 25 million years old, it is the oldest lake in the world.

A Russian mini-submarine attempting to set a record for the deepest freshwater dive on July 29, 2008, was originally reported as being successful, but a correction later emerged that reported the MIR I failed to do so, reaching a depth of only 1,580 meters (5,200 ft).

The Committee inscribed Lake Baikal as the most outstanding example of a freshwater ecosystem on the basis of natrual criteria (vii), (viii), (ix) and (x). It is the oldest and deepest of the world´s lakes containing nearly 20% of the world´s unfrozen freshwater reserve. The lake contains an outstanding variety of endemic flora and fauna, which is of exceptional value to evolutionary science. It is also surrounded by a system of protected areas that have high scenic and other natural values. The Committee took note of the confirmation of the revised boundaries of the site, which correspond to the core areas defined in the Baikal Law (excluding the five urban developed areas). It also noted that the special Lake Baikal Law is now in its second reading in the Duma. Finally, it noted concern over a number of integrity issues including pollution, which should be brought to the attention of the Russian authorities.

Lake Baikal seal
The nerpa, or Lake Baikal seal

Lake Baikal long ago became famous for the purity of its waters and surrounding shores, a pristine state that had been seriously threatened by planned industrial development in recent years. Luckily, Baikal was one of the first regions to benefit from the new Russian government's reversal of decades of anti-environmental industrial policies. Since 1992 Lake Baikal and the entire surrounding area have been designated as a national park, and Baikal is today a naturalist's paradise and an idyllic holiday destination. With fine beaches, excellent hiking, birdwatching, and pleasure boating, Baikal is well-positioned to become one of the most attractive vacation spots in Asia.

The Baikal basin, enormous in extent and depth, from the morphological viewpoint, represents a junction of three original troughs, more deeper South and Middle troughs and relatively shallow North trough. The troughs are divided by a prominent elevations of the bottom, the intradepressional uplifts.

The scientists indicate that unlike southern Baikal, where there is no connection between land and underwater reliefs, the most of underwater structures of North Baikal in western and eastern coast are distinctly of superficial origin. They held their shape under water. The latest bathymetric data show that the Baikal basin is cut by a continuous elevation of the bottom from the Olkhon island through the Ushkany islands and farther to the northeast. This is the Academic ridge.

In 1977 the Limnological Institute together with the Institute of Oceanology, USSR Academy of Sciences, carried out deep-sea visual studies of underwater relief, using the "Pisces" an apparatus of autonomous plunge and underwater sailing. In southern trough of the lake 42 submersions were carried out, among them 5 to the depth of more than 1000 m. At this period the record depth of submersion of a man in fresh reservoirs, 1410 m, was reached.


Tuesday, March 3, 2009

The Photochromic of the sea - Cuttlefish

Cuttlefish is the Underwater animal which the same class with squid, octopuses and nautiluses. Despite their common name, cuttlefish are not fish but molluscs. Recent studies indicate that cuttlefish are among the most intelligent invertebrate species.


They have an internal shell, large W-shaped pupils, eight arms and two tentacles furnished with denticulated suckers, with which they secure their prey.

Cuttlefish eat small molluscs, crabs, shrimp, fish and other cuttlefish. Their predators include dolphins, sharks, fish, seals and other cuttlefish. Their life expectancy is about one to two years.


Cuttlefish are photochromic and are sometimes referred to as the chameleon of the sea because of their remarkable ability to rapidly alter their skin color at will. Their skin flashes a fast-changing pattern as communication to other cuttlefish and to camouflage them from predators. This color-changing function is produced by groups of red, yellow, brown, and black pigmented chromatophores above a layer of reflective iridophores and leucophores, with up to 200 of these specialized pigment cells per square millimeter.

The pigmented chromatophores have a sac of pigment and a large membrane that is folded when retracted. There are 6-20 small muscle cells on the sides which can contract to squash the elastic sac into a disc against the skin. Yellow chromatophores (xanthophores) are closest to the surface of the skin, red and orange are below (erythrophores), and brown or black are just above the iridophore layer (melanophores). The iridophores reflect blue and green light.

Iridophores are plates of chitin or protein, which can reflect the environment around a cuttlefish. They are responsible for the metallic blues, greens, golds, and silvers often seen on cuttlefish. All of these cells can be used in combinations. For example, orange is produced by red and yellow chromatophores, while purple can be created by a red chromatophore and an iridophore.

The cuttlefish can also use an iridophore and a yellow chromatophore to produce a brighter green. As well as being able to influence the color of the light that reflects off their skin, cuttlefish can also affect the light's polarization, which can be used to signal to other marine animals, many of which can also sense polarization.