Antarctic Animal Adaptations
Antarctica is a very harsh and extreme environment though is very rich in wildlife due to the very high productivity of the Antarctic Ocean during the summer months. Long days provide abundant light and copious nutrients brought to the surface layers by ocean upwellings along the Antarctic Convergence fertilize the growth of phytoplankton. Animals need to have a whole range of specializations to be able to take advantage of these conditions.
- Anatomical - Structures of the body.
- Behavioural - The manner in which animals move and act.
- Physiological - The internal functions of the
Largest of all penguins by a considerable margin. Animals of the very deep south and the only large animal that remains in Antarctica in the depths of the long dark winter night.
Anatomical AdaptationsLarge size retains heat - Emperors are twice the size of the next biggest penguin, the king, so are able to survive the winter fast and the extreme cold temperatures endured at this time
Short stiff tail helps balance on land, forms a tripod with heels on ice to give the least contact area to prevent heat loss
Chicks have soft down for insulation, this is a more effective insulator on land than the parents feathers, but of little use in the sea, they must moult before they can swim
Behavioural AdaptationsHuddle together in the winter to conserve heat, without this they wouldn't be able to survive the Antarctic winter
Unlike other penguin species, they are not aggressively territorial, hence the huddling (above)
Breed during the depths of the Antarctic winter, so the chicks are large enough to become independent during the summer abundance of food
Physiological AdaptationsA complex heat exchange system allows 80% of heat in the breath to be recaptured in the nasal passages
They can dive to a depth of 1,800 feet (550 meters) and hold their breath for up to 22 minutes, so are able to reach and exploit food resources that other birds can't reach
Males can make "milk" in the oesophagus which can be used to feed chicks in the winter before the female arrives back from fishing
The second most southerly penguin species after the Emperor, breed in the far south, but leave it to head north with the onset of winter.
Anatomical AdaptationsShort wings reduced to flippers for swimming underwater
Backward pointing barbs on tongue to stop slippery prey escaping
Black above and white underneath makes it harder to see in the sea, and helps warming / cooling on land, back or front to the sun according to whether they are hot or cold
Behavioural AdaptationsMigrate north at the end of the brief summer
Arrive in the south early in the summer season, to take best advantage of the seasonal abundance of food
Tobogganing sliding on their front while pushing with legs, saves a lot of energy in long journeys
Physiological AdaptationsMuscle has large amounts of myoglobin to hold extra oxygen that is used up during a dive
A counter-current system in the legs means that the feet are kept just above freezing and operated by muscles in the legs via tendons, this reduces heat loss
During a deep dive, the heart rate slows from 80-100 down to 20 beats per minute
The most southerly dwelling of all mammals. Live at the edge of pack ice wherever there is a breathing hole or tide crack.
Anatomical AdaptationsFore and hind limbs developed into flippers for swimming
Smooth, streamlined shape to pass easily through the water
A substantial blubber layer lies under the skin acting as insulation, so allowing the seals to swim indefinitely in frigid Antarctic waters down to -2C
Behavioural AdaptationsSeals keep open breathing holes in the ice by rasping back and forth with their teeth, so allowing them to live further south than any other mammal
They can swim large distances between breathing holes and cracks, finding the next hole using a form of sonar with high pitched sounds
They avoid the "bends" when diving by exhaling first and allowing the lungs and air passages to collapse
Physiological AdaptationsWeddell seals can dive for over an hour, though 20 minute dives are more common. They can dive to 600m
The "cost" of diving in terms of extra oxygen consumption is about 1.5 x the sleeping rate - this is much lower than other diving seals and birds
The blood has high haemoglobin concentrations and can carry 1.6 times more oxygen than human blood
A Crustacean member of the zooplankton, krill are about 4-5cm long and feed on phytoplankton. Unusually large for zooplankton they are eaten by just about anything and everything that comes across them
Anatomical AdaptationsVery fine filtering net or "basket" formed by 6-8 pairs of limbs that can capture phytoplankton down to 1µm (1 micrometer, a millionth of a meter), the smallest that there are, no other zooplankton of this size can do this
Small bioluminescent organs are found on several places on a krill's body, they have a reflector at the back, a lens at the front and can be directed using muscles, the function is not fully known, it may be connected with schooling or mating. For this reason krill are sometimes called "light shrimp"
Behavioural AdaptationsSwarming behaviour similar to schools of small fish as a defence against predators, such swarms can have up to 10,000 to 30,000 individuals per cubic meter of sea water
In the winter and spring they are found beneath sea ice where they feed on algae growing on the under side of the ice which they rake off in a methodical manner like a lawn mower
Physiological AdaptationsCan withstand long periods of starvation (up to 200 days) by using their muscle as a reserve, the krill shrink in the process, this happens over the winter months when the krill are under seasonal sea ice and there is little or no photosynthesis
Female Antarctic krill can lay up to 10,000 eggs at a time, they can do this several times in a season
Balaenoptera musculus Sulphur Bottom Whale
The largest animal ever to have lived, larger than any dinosaur, the huge bulk being supported by the sea. They can eat up to 4 tonnes of food a day in the Antarctic summer, they feed for about 8 months and then fast for 4 months living off their fat reserves.
Anatomical AdaptationsBaleen plates in the mouth instead of teeth, made of keratin, the same tough protein that makes hair and nails. They hang down from the upper jaw forming the two uprights of a triangle with the lower jaw being the flat third side.
55 - 68 ventral grooves that extend from the lower jaw to the navel. These allow a huge mouthful of water and food to be taken, expanding to about 6 times larger than normal size.
Blowholes (the two nostrils) located on top of the head.
Behavioural AdaptationsBlue whales migrate to polar regions during the summer months of that region. There are distinct southern and northern populations which go to their respective pole, none go to both poles.
Blue whales use sound to communicate with each other and also possibly as a means of finding krill swarms. They have been described as making the loudest noise made by any animal at 180 dB or more.
Physiological AdaptationsAdult blue whales have a daily energy requirement in the region of 6.3 million Kilojoules (1.5 million kilocalories). This is supplied by up to 3.6 tonnes or 40 million individual krill eaten per day which all have to be processed by the digestive system.
Like many other air breathing diving animals such as other whales, seals, and penguins, blue whales have muscles rich in myoglobin. This is an iron containing protein similar to haemoglobin that stores oxygen in the muscles.