water

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Sharks

Sharks are one of the most formidable inhabitants of the ocean. The lack of bone tissue and Gill covers, especially the structure of scales, and many other features of the structure speak of their ancient origin, as confirmed by paleontological data the age of the first fossil remains of sharks is determined approximately 350 million years. Despite the primitiveness of the organization, shark — one of the most perfect predatory fish of the ocean.

Over a long period of existence they managed to adapt perfectly to life in the water column and now successfully compete with bony fish and marine mammals. Unlike bony fish sharks and rays don’t spawn and lay their large, covered with a Horny shell eggs or give birth to live young.

The highest values reach whale (up to 20 meters) and the so-called giant shark (up to 15 meters). Both these and others, like baleen whales, they feed on planktonic organisms. Wide and gaping jaws, these sharks move slowly in the midst of clusters of plankton and filter the water through Gill openings covered by a network of special outgrowths of surrounding tissue. Giant shark profiltruyte an hour to one and a half thousand cubic meters of water and remove all organisms larger than 1-2 millimeters. Continue reading

Tiger shark

Tiger shark (Galeocerdo cuvier) is the only species of the genus tiger sharks (Galeocerdo). The species was first described by Peron and Lessueur in 1822, under the name Squalus cuvier. In 1825 Blainville has included this species to the genus Carcharhinus, Carcharhinus lamia calling it. Müller (Muller) and Henle in 1837 tiger shark was transferred into a separate genus Galeocerdo and gave her the specific name of Galeocerdo tigrinus. Gill in 1962 called the described type of Galeocerdo tigrinus. Currently, the tiger shark is the scientific name Galeocerdo cuvier, on the grounds that this species gave the name of her who first described it Lessueur, however, the generic name had to change, as the tiger shark belongs to the genus Squalus (spiny sharks), as suggested Lessueur, and is a separate a monotypic genus, as noted above.

Systematics

Class: Chondrichthyes (cartilaginous fish)

Subclass: Elasmobranchii (platinotipiya, or elasmobranchs)

Superorder: Selachimorpha or Selachii (sharks)

Order: Carcharhiniformes (carcharhiniformes) Continue reading

A pond for goldfish

oAll your favorite goldfish are one of the first that were adapted to life in aquariums. This smallest member of the carp family. Ponds with goldfish first appeared in the Tang dynasty in China. In a time of cyprinids living in this dynasty, there have been some genetic mutations and individuals appeared, painted in gold and yellow-orange. The Chinese Emperor ordered to maintain the resulting first pond with goldfish and thought it was exceptional luxury of the Imperial dynasty. It was a symbol of Royal splendor. Breeding exclusively among the resulting new individuals led to greater mutations.

For goldfish it is necessary to equip the fresh-water ponds. The pH level in water should be 6.0-8.0, and water temperature can range from 4 to 40C. Overall, the gold fish are very hardy, but it is hard for them to live in water with high temperature. For comfortable existence zolotusky requires a lot of oxygen in the water, so the thin layer of ice that can form on the surface of the water in the pond in winter is not desirable. Furthermore, goldfish require no special care, is very colorful and can live in almost any pond. Continue reading

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