Vērotāja wrote:Interesanti. Ja dzīva radība sasalst, ķermeņa šķidrums pārvēršoties ledū izplešas un saplēš šūnas. Tāpēc radības uz ziemu slēpjas vietās, kur temp augstāka par sasalšanas temp un tuvojoties salam laižas ziemas stingumā – apturētas dzīvības stāvoklī jeb anabiozē.
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Bet tā Aļaskas vardīte sasalst, tas tiešām ir dīvaini no fizikas viedokļa. Pat neticami mazliet.
http://www.snopes.com/photos/animals/frozenfrog.aspIzrādās, ka Sunshine ievietotais attēls esot dārza dekors un attēls jau gadus klejo internetā. Tomēr tādi aukstumizturīgi dzīvnieki tomēr eksistē.
Tāda ir Wood frog/Лесная лягушка (лат. Rana sylvatica)/ Meža varde Aļaskā.
Tajās lielākā daudzumā ir īpašas vielas - tāds kā antifrīzs, kas pazemina sasalšanas temperatūru un tādējādi tiek ierobežots ledus daudzums ķermenī.
Frozen Wood Frog survives the winter in Alaska, Steve Downer - Wildlife Cameraman
"A sequence filmed by UK wildlife cinematographer Steve Downer for Denali - Alaska's Great Wilderness, a film in the PBS series The Living Edens.
The Wood Frog ( Rana sylvatica ) survives the winter in suspended animation underground. With its body frozen, the frog shows no signs of breathing or a heartbeat. A natural form of antifreeze prevents the insides of the frog's cells from freezing and causing tissue damage. In the spring the frog thaws out and resumes normal activity."
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"The way wood frogs avoid freezing to death is due to so-called cryoprotectants — solutes that lower the freezing temperature of the animal's tissues. These include glucose (blood sugar) and urea and have been found in much higher concentrations in the Alaskan wood frogs than in their southern counterparts.
Increased levels of cryoprotectants help the frogs' cells survive. In most animals, prolonged exposure to subzero temperatures causes cellular shrinkage — a process in which the formation of ice in the tissues pulls water from the body's cells, essentially sucking them dry and eventually killing the cell. (Related: Champions of the Cold.) But cryoprotectants help the cells resist that shrinkage. "The solutes tend to depress the freezing point [of tissue]," said (Jon Costanzo of the Department of Zoology at Miami University in Ohio). "It limits the amount of ice that actually forms in the body at any part. The more of that cryoprotective solute you can accumulate, the less ice will form and therefore the less stress there is on cells and tissues."
http://www.snopes.com/photos/animals/frozenfrog.asp
Tā ka bildīte laikam ir greiza, tomēr vardītes ar šādu īpašu pārziemošanas taktiku tiešām eksistē!
Daba ir tik daudzveidīga.
Liekas, ka jenotam šoreiz nebija cerību uz vakariņām..