Thursday, November 1, 2007

There's a lot more life in Siberia than you ever imagined...

Lake Baikal, (озеро Байкал) at 1,637 meters (5,371ft) deep, is the deepest and largest lake in the world, and is the largest freshwater lake by volume (23,000km3). It contains one fifth of the world’s surface freshwater. Although its surface area is not all that impressive, (at least when compared to Lake Victoria of Africa) Lake Baikal has as much water within it as all of North America’s Great Lakes combined.

Located in Southern Siberia, between Irkutsk Oblast and Buryatia, the name comes from the word Байгал which in the Mongolian language means "nature".

Known as the “Galapagos of Russia”, Lake Baikal is home to 1,085 species of plants and 1,550 species and varieties of animals and 80% of the species that live there cannot be found anywhere else in the world. It is one of the oldest lakes in geological history, estimated at 25-30million years old…thanks to its age and isolation it is of exceptional value to evolutionary science.

It’s a pretty cool, almost sci-fi sort of place. It’s filled with some really strange looking creatures, but for this blog I’m going to focus on just one, the Nerpa, one of the only species of entirely freshwater seals in the world.

Nerpa are unique among seals in many ways, (and not only because they look like some kind of big grey balloon).

They are, along with two subspecies of the Ringed Seal, the only seals to spend their entire lives in fresh water. They can grow to be over 50 years old, making them the longest lived seals, and they nurse their young on milk for twice as long as any other seal species.

Scientists are still not sure as to how the seals originally came to Lake Baikal, seeing as it is hundreds of kilometres away from any ocean. But it is thought that they probably came at a time when there was a sea-passage which linked the lake with the Arctic Ocean.

Nerpa generally tend to prefer the more northern parts of the lake, as the longer winter keeps the ice frozen for longer, which is good for looking after their pups. The females raise the pups on their own, and dig them a large den under the ice. The pups remain here until spring; when the ice melts and the dens collapse, then the pups are left to fend for themselves. Nerpa usually only give birth to one pup, however they are the only seal that has the ability to have twins.

Nerpa (this is kind of cool) have two litres more blood than any other seal of their size and as a result can stay underwater for up to 70minutes if they are frightened or in danger.

So what do these guys eat? Well, a variety of different shrimp and fish make up their main diet, but their main food source is this spiny little guy here.

The Golomyanka, a type of sculpin that lives solely in Lake Baikal. Isn’t he ugly?
Amazingly, sculpin can live for several hours out of water if kept moist. They use their large pectoral fins to stabilize themselves on the floor of flowing creeks and rivers.
This fish lives in silty areas, and as a result it usually has a lot of grit and silt in its stomach. This silty grit scours out the Nerpa’s innards and removes parasites.

(Dr Denner, I've changed my mind. I do want to study ecology/biology when I go on exchange to Russia...)

And now, in closing, here's a clip of some Nerpa swimming....

1 comment:

Dr. Michael A. Denner said...

we'll make it work, bim. AWESOME ENTRY.