Jellyfish displace fish and become dominant in the oceans
Coastal waters from California to Australia was captivated by the jellyfish. If population growth continues, after fifty years, these marine animals displace fish and become dominant in the oceans.
The number of jellyfish naturally increase every 12 years. Next 4-6 years, it remains unchanged, and then begins to decline. However, the last decade their population and habitat is expanding at an accelerated pace. The jellyfish is more likely to end in different regions and thrive in a new place. In this case, the aliens cause irreparable damage to the ecosystem.
1. This summer, the Moscow river appeared tropical jellyfish craspedacusta, the dimensions of which do not exceed 3 cm. the Usual habitat of craspedacusta — the Amazon river in South America, but today it spread over all the continents.
2. In Primorye this year in the coastal waters noticed robilem (rhopilema esculentum) is a jellyfish of enormous size. The diameter of the umbrella can reach half a meter. Usual habitat — the Japanese, Chinese and the Yellow sea.
3. Off the coast of Japan the number of jellyfish is increasing since 2002. Over the last ten years, the damage the Japanese economy amounted to $110 million jellyfish poison the fish in the nets clog the pipes in the cooling systems of local power plants.
4. In the 1990s Medusa-grinevitskaya Black sea. The number of jellyfish was 90% of the mass of all living organisms in the pool. When the sea came the jellyfish is a predator beroe ovata, the ecological balance began to return to normal.
5. In 2002 on the French Riviera jellyfish Pelagia tore the fishing nets weighing more than 2 thousand kg. In 2008 from jellyfish that attacked the coast of Tuscany, was already rescued tourists.
6. In 2006 on the coast of Spain from the invasion of Pelagia suffered 14 thousand people. And in 2007 on the beaches of France threw out 11 million tons of jellyfish. In 2008 for medical help addressed more than 500 people.
The structure of the jellyfish
The structure of the jellyfish
Jellyfish are among the most ancient life forms on Earth, they appeared more than 600 million years ago and has changed little during this time. These animals are relatives of sea anemones and corals that do not have bone framework. Consist of 95% water, 3-4% salts, and 1-2% protein. Heart, circulatory system and the brain are absent, the nervous system — simple neural network.
The body of a jellyfish — it is the bag which wall consists of the outer covering and protective epithelium (ectoderm) and inner secretory and digestive epithelium (endoderm). The cavity of the bag opens only one hole — mouth and is a digestive.
Some species of jellyfish have 24 eyes. Jellyfish at their stations, they can distinguish colours and are 360 degrees. Their eyesight is better than birds, but what it this “gelatinous umbrellas”, scientists are at a loss to explain.
The scheme of reproduction of jellyfish
Jellyfish — heterosexual beings. Sex glands they are located in the pockets of the stomach. Their reproduction is similar to reproduction of fish. Planula, the larvae turn into adults in a few months.