Text and pictures © 1993-2021 Guillaume Dargaud
Last updated on 2020/03/19
"Many times I have thanked God for a bite of raw dog." — Robert Peary, polar explorer
Left: Weddell seal (Leptonychotes weddelli) bathing in the sun near Terra Nova Bay.
Their fat protects seals efficiently from the cold, both at sea and outside. They can weight up to 600kg, a good portion of which is fat. As an additional protection against the cold the have a thin layer of very dense fur. The male is bigger than the female, up to 3m long, but is not seen too often on the ice. They are very good divers, able to dive down to 600m and hold their breath for an hour. Their only predator is the killer whale, sometimes seen off the shores of Antarctica. During those dives they catch and eat mainly fish, squids, octopuses, krill, crabs and shrimp.
Left: A newborn Weddell seal, still wrinkled from the womb, opens his eyes to the world.
When seals are young, they like to be scratched under the 'arms'. Baby seals have never been hunted in Antarctica and big ones have not been hunted for about a century (whalers used to catch them when they couldn't find enough whales). From the dark color of baby seals, it's easy to tell they don't have land predators: baby seals from the arctic are white to try to hide from the sight of polar bears...
If the ice is not too thick, Weddell seals can drill a hole in it by opening their mouth wide and turning it repeatedly against the ice. They normally never venture inland, but mummified remains of seals have been found in the Dry Valleys, hundreds of km away from the sea.
Right: A young seal underwater. Attracted by the noise of my camera it came close and touched it with its nose.
Left: Baby seal bathing in the spring sun on the sea ice.
There you'll find more details on Weddell seals and their diving capabilities.
Left: Couple of crab-eater seals (Lobodon carcinophagus).
Although very abundant around Antarctica, they are not very common around DdU and I saw only a couple of them. The only thing I know about them is that they don't particularly eat crab but krill which they filter out of the water with their uniquely shaped teeth. They may reach up to 2.5m and weigh more than 200kg. They often have scars from leopard or killer whales attacks.
Right: The infamous leopard seal (Hydrurga leptonyx), the main predator of Adelie penguins at sea.
When they catch one, they play with it just like a cat with a mouse. You wouldn't want one to mistake you for a penguin (it's happened a few times to people standing on the shore !). They come to DdU mainly when the chicks go to the sea for the first time, still learning to swim. Penguins are extremely tough animals, though, I've seen several that survived such attacks with no feet or tails that successfully manage to raise chicks every year.
Their name comes from their spotted fur and also from their huge mouth and powerful jaws. Females are larger than males and may reach 4m and weight up to 450 kg. They are solitary predators and eat just about everything, from krill to other seals but particularly appreciate Adelie penguins. They often attack penguins that are walking on broken floating ice by bursting through the ice; you can tell penguins are nervous when walking on broken ice by the speed they go ! And they don't stand near the shore. It's also something that has cause more than a few scares in my colleagues when they saw a leopard seal burst out of the water at their feet, probably thinking they were some kind of fat penguin.
Left: Amazing video of an encounter between National Geographic photographer Paul Nicklen with a leopard seal. The leopard fed penguins to his camera and tried to teach him how to catch preys !
Left: Notothenia Rossi, one of the 19 species of fish found near DdU.
It is one of the only species that stays near the coast even during the winter. Size about 15cm. Although the Antarctic ocean is one of the richest in the world, few fish wander near the coast because the water gets too cold (-1.8°C, 28.7°F). And the Antarctic convergence adds another barrier: it's a current that circumnavigates the continent, with a sudden difference of 3°C from the northern water, also a lower salinity, higher oxygen and higher density making so that the species living in it are highly specific. Fishing them in winter is fun: drill a hole in the ice, put down a baited line, get it out and it will flash freeze in a matter of seconds. They are not very good to eat, especially since the best place to fish them is near the bathroom drain...
Right: Some Ice Fish caught and opened up for the sake of science.
Some Antarctic fish happen to have a very peculiar thermoregulating muscle in their jaw. Most antarctic fish keep their body temperature identical to the water temperature, using a high quantity of glycopeptides in their blood as antifreeze, but not this specie thanks to a special thermoregulating muscle. Here the muscle has been removed for analysis. Biologists study also their digestive enzymes for cold temperature detergent applications.
Another weird fish is the family of Channichthyidae, a.k.a. ice fish or ocellated icefish which is almost transparent thanks to the complete absence of hemoglobin (a protein which gives the red color to blood and also carries oxygen around the body); even its parasitic leaches are transparent ! Without hemoglobin, the oxygen gets carried to the organs by being fully dissolved in the plasma. Remember that cold water can contain more oxygen than warm water (hence the quantity of life in polar oceans), but it also applies to plasma. Still, the heart needs to pump much more liquid around and is bigger than in normal fishes and also beats five times faster. Its metabolism is also kept to a minimum. Why is it an evolutionary advantage ? No idea.
Left: This antarctic ground algae is the only green thing growing near DdU, probably Nostoc Commune which is actually a mat of cyanobacteria.
Picture size about 1cm. It grows in or around mud puddles in summer. In winter it dries out or gets covered by snow and you can't even see it. I can tell you that you are glad to see some real green grass when you get back from Antarctica ! In the warmer Antarctic Peninsula there is some hardy grass and tiny flowering plants growing.
So the land life is fairly poor, in high contrast to the sea life which is teaming with life (cold water can absorb more oxygen and less salt than warm water). Phytoplankton, the 'grass' of the sea, is a mass a tiny micro-organisms that form the base of the Antarctic food chain. In summer the long days of sunlight allow those tiny algaes to bloom quickly, often on the underside of floating ice. They are in turn eaten by zooplancton (tiny animals), which gets eaten by krill, fish and squid which get in turn eaten by penguins and seals, and the chain finishes in the stomach of the killer whale and sea leopard.
Right: Antarctic lichen
This lichen, is one of the rarest life form on Earth: it grows only on one spot about 10m by 2m near DdU. I am not sure if this is one, two or three different lichen, because there is some orange one (possibly Xanthoria elegans), some gray one and some black one (background). Other lichens can be found throughout Antarctica and there rate of growth is incredibly slow, from 1cm per century to 1cm per millennia ! They can survive for long periods of in a dry and inactive state and can also perform photosynthesis at temperatures as far down as -20°C. Picture size about 2mm. More info about lichens.
This cryptoendolith (hidden-in-rock in Greek) is one of the strangest life form of all. It is a whole ecosystem growing inside clear rocks, just a few millimeters under the surface and includes an association of bacteria and algae. It is visible as the green stripe on this split rock. Enough light and water gets through the rock for photosynthesis, and that's all you need to live, right ? Picture size about 5cm.
Right: Two adults in their 'seal hole'. They normally use cracks in the ice, but they can also drill a hole with their teeth if need be.
See the Penguin FAQ, the Dome C FAQ or the Climate FAQ for more frequently asked questions. And for a different kind of Antarctic fauna, there's always Nick's site.
Pictures of the penguins and birds seen around the base.