Thursday, 6 December 2012


The stormwater pond near our house is frozen over. 

I know what you are thinking right now. So what?  It’s a pond, ponds freeze over in the winter.  So do lakes, rivers and the cup of hot chocolate we left out the other day while tobogganing. But to Beans this was very upsetting news (as was the hot chocolate) because there are frogs in that pond and are the frogs FROZEN?

She knows enough about ice fishing to know that the fish are ok, they hang out down near the bottom where it's not frozen and people (like Daddy) catch them. Clearly the frogs can't go south for the winter, that is an exceptionally long way to hop. And they don't go down to the bottom of the big lake to hang with the perch. So they are here somewhere, but where? The answer is that they are exactly where they always are - in the pond (or the woods if you happen to be a wood frog). Frogs use a form of hibernation to get through the winter.

Not surprisingly, aquatic frogs hibernate in the water. The water frogs, like the leopard frogs (the ones with spots) and green frogs (the ones that sound like elastic band guitars) we usually catch, basically go hang out near the bottom where it's warmer and basically sit there until spring. The water temperature at the bottom is pretty consistant at 4°C in the winter, which is why fish, frogs and turtles go hang out there. They are a bit slower (anyone who has tried to zip up a 4-year-olds jacket in -10°C without mittens on knows that you are slower and clumsier in cold) but they even swim around a bit. The turtles bury themselves in the mud at the bottom, the frogs don't because that would suffocate them, so they just sit partially in or on the mud at the bottom. Their metabolism slows down enough from the cold that they don't need to eat and get by on limited oxygen.

And while that's pretty cool, it's not that overly exciting I know. But wait, there's more!

Hi there! I'm a wood frog and I'm awesome.

Terrestrial frogs - the wood frogs specifically - do something that will knock your socks off. They freeze. Seriously - they freeze and thaw as the temperature fluctuates! They hop on into a crack somewhere and then just freeze for the winter. They go into suspended animation (like in Red Dwarf - bonus points for awesome british science fiction show reference!) where their heart stops and their brain stops and they are basically a frogsicle - to quote the researcher: "when you drop it, it goes clink". To stop their organs from freezing and collapsing they produce mass amounts of glucose which packs into the cells and keeps them viable. Their body temperature can drop to as low as -6°C. When it warms up they thaw out, their heart starts back up and off they hop!

Watch it happen:


And the awesomeness doesn't end there! This is such an impressive feat of nature that it is being studied to help out in human organ transplants. Right now you can't freeze organs for transport, which gives them a limited shelf life and makes it necessary for donors and recipients to be in surgery on the same day, the closer the better. If the frogs method of removing water from organs with special proteins and the extra glucose can be mimicked it means there could be organ storage and longer transport distances. Livers for everyone!

So, while Beans' fear was true, some of the frogs are frozen, it's okay that they are frozen and now apparently we have to go find one. So if you see a little girl in pink zebra mittens out in the woods in the snow peering into cracks in a log, that's Beans, looking for a frogsicle.

1 comment:

  1. My favourite post yet! And oh so cool-- I never knew some frogs froze!