Antarctic Invertebrates - Antarctica's "Other"
Everyone has heard of and
seen many pictures of the charismatic mega fauna
that lives in Antarctica, you've probably seen
films and cartoons featuring them and may even
have a toy version somewhere in your house.
and Asia have elephants, Antarctica
has 1mm midges and springtails, where
they have lions and tigers, Antarctica
has predatory mites and while the Arctic
has polar bears, there are water bears
about 0.2mm long.
whales, seals and other Antarctic animals are
certainly especially well adapted to the difficulties
of life in the Antarctic freezer, theirs is
not the whole story. As anywhere else in the
world, there are many other animals around that
don't get anywhere near the same degree of attention,
animals without backbones, the invertebrates.
Unlike almost any other place on earth, invertebrates
on land in Antarctica generally don't make their
presence known. They don't buzz around your
head, try to bite you or keep landing on your
potato salad and taking off again. Neither do
they leave slimy tracks across your path on
damp days, hide in your shoes or get eaten by
The main thing you would notice about Antarctic
terrestrial (land) invertebrates is that they
are small, very small. The largest of them is
a wingless midge,
Belgica antarctica at around 2-6 mm in length.
are only 67 species of insects recorded in
Antarctica, which is absolutely nothing
compared to their teeming hoards on all
Another thing that characterizes them is that
they live stop-go lives according to the temperature.
When it rises above freezing point, they warm
up (a process that often includes defrosting)
and are active for a while as long as it stays
warm. When it cools down again, so they slow
down, stop and possibly freeze again. The go
portion of their lives typically lasts for a
few hours or even less than an hour while the
stop portions may last for weeks or months on
They may be small and hard to find, but terrestrial
invertebrates in Antarctica are amongst the
hardiest of its citizens living in the harshest
environments, places where as recently as 30
years ago it was thought that nothing could
live. Inevitably to find terrestrial Antarctic
invertebrates, you have to go looking for them.
Rotifer (wheel animal)
Tardigrade (water bear)
Antarctica has the smallest permanent land fauna
of any continent. Whereas Africa and Asia have
elephants, it has 1mm midges and springtails,
where they have lions and tigers, Antarctica
has predatory mites and while the Arctic has
polar bears, there are water bears about 0.2mm
Than again all of these invertebrates also live
on all of the other continents, so is there
anything special about Antarctica's Invertebrates?
Why are Antarctic
invertebrates of interest?
The terrestrial Antarctic ecosystem is one of
the most extreme places on earth to live, in
order to live there animals have to endure conditions
that for many years scientists thought were
unendurable until they found the animals that
were living there. Invertebrates are of interest
in Antarctica for several reasons:
- How do they do
it? The fact that they can live in
Antarctica is one reason that scientists
are interested in these invertebrates, they
are much hardier than their relatives from
other parts of the world.
- How is any one
factor affecting them? Antarctica
is often regarded as a giant laboratory
where things can be studied more easily
than in the rest of the world. There is
little or no direct local influence from
man and there are less species so making
observations clearer as there are less other
influencing factors to hide what is happening.
- What can they tell
us about other planets? Nothing directly
probably, however Antarctica is more like
other planets than anywhere else on earth,
the Dry Valleys region with its constant
dry cold and strong winds stands in for
Mars when testing equipment and trying things
out. There are organisms that live in places
in Antarctica that until fairly recently
were thought to be totally sterile, they
can show us where life can exist and where
to look for life on extra terrestrial bodies
- and maybe what it might look like.
What's the problem
with dealing with extreme cold?
In a word - Ice.
All living cells are mainly water, it serves
to dissolve and transport substances over short
distances, and give cells bulk and shape, without
it there would be no life on earth.
by Helen Filatova,
Licensed under the CC-By-SA-3.0.
Below freezing point though, that terribly useful
and vital water becomes deadly. It forms sharp
ice needles which grow, piercing and destroying
cell membranes and killing tissues. In humans
the process causes frost bite and can result
in the loss of fingers and toes if you catch
it fairly quickly, the loss of arms and legs
or your life if you don't.
The problem for invertebrates in Antarctica
is that they are at the mercy of the external
temperature, warming up and cooling down with
the day or a chance patch of sunlight. The average
temperature in Antarctica over the year is below
freezing in most places, so the animals have
to avoid having their tissues destroyed by those
How can animals
|1 - Freeze
depress the freezing
point of the water in the cells.
Sea water freezes at around -1.9°C due
to the dissolved salt rather than at
0°C for pure water, the same principle
can be used in body tissues.
2 - Freeze tolerance
- the next
step is to make anti-freeze in the body
tissues. Specific proteins act
like cushions at the end of forming
ice crystals, they prevent the further
growth of the crystals. The ice forms
but it is contained.
3 - Cryoprotective
dehydration - dehydration
in preparation for freeze drying.
The most extreme adaptation. Antarctic
nematodes and tardigrades in response
to falling temperatures dry themselves
out before they freeze and can stay
that way for months or even years. When
the temperature warms up again enough
for there to be liquid water around,
they warm up, rehydrate and continue
Where do terrestrial
invertebrates live in Antarctica?
anywhere there is bare soil to give a water
film and where there is productivity in the
form of growth of plants such as algae, mosses
or liverworts. They are also often found around
the nests of birds that nest on isolated mountain
peaks elevated from the surrounding ice called
from the peak of the nunatak Plogen, 20 kilometres
away is the nunatak Basen, where a Swedish station
is situated. Invertebrates are found living
on these peaks separated by barren ice fields.
Photo: Ingemar Jönsson.
The Dry Valleys region of Antarctica, the closest
of any place on earth to the planet Mars, though
still home to invertebrates such as nematodes.
Nematode research in the Dry Valleys
Antarctic forest, a small clump of moss on
Signy Island, home to some of the largest
land animals in Antarctica.