I don't understand this. Water freezes at 0 C. Water expands when it freezes. At -25 C, is it expanding more than when it originally froze? Is there something else in the beetle egg makeup that expands when it freezes and only does so at -25 C? Doesn't make sense to me...
---John Holmes...
John,
It's not just the fact of expansion upon freezing. It's also a matter of how what's in the egg freezes and when. For example, Antarctic ice fish can live, move, and breed in water that is almost -2C. Here's a nifty middle school
experiment that demonstrates what's going on. In effect, ice fish have evolved special systems, including unique blood, that allows them to be active in subfreezing temperatures. IIRC, there is a type of frog that can be frozen essentially in a block of ice and still be revived with no ill effects. The secret is in a class of chemicals called glycoproteins, which are basically in vivo (in living organisms) antifreeze. These chemicals have two effects that are protective of organisms (and perhaps eggs) that survive subfreezing temperatures. First, they lower the temperature at which the liquid (blood and cellular fluids) freeze so that excursions slightly below the freezing temperature of pure water will not result in the liquid freezing solid. Second, and most importantly, they prevent the formation of ice crystals within cells and tissues. These crystals destroy tissue as they grow and is what results in irreparable damage upon freezing.
Generally, the more complex the organism, the more unlikely that it will survive deep freezing. People? Presently impossible. Cells, seeds, and tissues, etc. are routinely flash frozen in liquid nitrogen for long term storage. Like in flash frozen fish, the water is frozen before it has a chance to form crystals, thus preventing the damage that occurs because of ice crystal growth.
So, beetle eggs are simple constructions which may well contain biological antifreeze. Freezing damage happens at both gross and fine levels and above a certain temperature, the combination are not necessarily fatal. Although there is a probably a dose-response effect. Check out the concept of "LD50" to learn more.
Wilkey