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 driven by long days providing abundant light and copious nutrients brought to the surface layers by the upwellings at the Antarctic Convergence.

Animals need to have a whole range of specializations to be able to take advantage of these conditions, those given here are those that are most relevant to living in Antarctica, there are many other adaptations of these animals.

Anatomical - Structures of the body.

Behavioural - The manner in which animals move and act.

Physiological - The functioning of the animal at levels from biochemical, to cellular, tissue, organ and whole organism levels.

Animal	Anatomical adaptations	Behavioural adaptations	Physiological adaptations
Adélie penguin - more Pygoscelis adeliae One of the "classic" penguin species, the second most southerly after the Emperor. Breed in the far south, but leave it to head north with the onset of winter.	Compact shape, low surface area to volume ratio to reduce heat loss Very dense specialized feathersfor insulation on land, fat layer under the skin for insulation in the sea Short wings reduced to flippersfor 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	Migrate 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 Build a crude nest of stones to lift the eggs above ground level to prevent chilling from melting snow in summer Gather at the ice edge in large groups before jumping in the sea in case of predators, increases individual survival chances	Muscle 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 Able to cope with a high saline diet due to salt glands and kidneys that produce concentrated urine (like many seabirds, penguins can drink sea water and gain water)
Emperor penguin - more Aptenodytes forsteriaa 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.	Large 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 Highly specialized bird skeleton a highly upright gait, short neck, short legs and long body Powerful claws on the feet help to gain a grip on snow, ice or rock when emerging from the ocean or when tobogganing	Huddle 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 No nest is made, eggs then chicks sit on the parents feet and covered by a fold of skin to keep them warm When the female lays her egg, it is passed over to the male, the female then goes to sea and will not return for an average of 115 days	A 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 The normal resting heart-beat is about 60-70 beats per minute (bpm), this goes up to 180-200 bpm before a dive as they load up with oxygen, as they hit the water, the rate drops to 100 bpm immediately slowing to 20 bpm for most of the dive Males can make "milk" in the oesophagus which can be used to feed chicks in the winter before the female arrives back from fishing Males can fast for up to 100 days
Animal	Anatomical adaptations	Behavioural adaptations	Physiological adaptations
Weddell Seal - more Leptonychotes wedelli The most southerly dwelling of all mammals. Live at the edge of pack ice wherever there is a breathing hole or tide crack.	Fore 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 Large eyes to help hunting prey under water and frequently under ice where light levels are very low Whiskers (vibrissae) that help the seals feel their way in the dark when catching prey	Seals 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 Males compete for underwater territories based around a breathing hole which gives access to females using the same breathing hole They flush fish out that are hiding in broken up ice by blowing bubbles into it	Weddell 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 Weddell seal milk is one of the richest produced by any mammal,containing about 60% fat The females mate shortly after giving birth, the embryo goes into a kind of hibernation for a few months so it is not born before the full year is up and it is the correct season
Antarctic Krill - more Euphausia superba A Crustacean member of the zooplankton, krill is a super-abundant organism about 4-5cm long that feeds on phytoplankton. Being unusually large for zooplankton they are eaten by just about anything and everything that comes across them	Very 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" Complex and highly developed compound eyes, one of the best visual structures in nature, though why this should be so in krill is a mystery	Swarming 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 Rapid backwards escape reactionin common with many other crustaceans with a pronounced flattened tail or telson, they can flip it backwards several times in succession to escape from danger -this is called "lobstering" Usually krill stay in deep water during daylight hours and come to the surface at night, this helps them to avoid predators	Can 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 Despite very cold water temperatures, krill are highly active,backwards lobstering takes only 55 milliseconds from stimulus (optical) to triggering of the escape response Female Antarctic krill can lay up to 10,000 eggs at a time, they can do this several times in a season
Animal	Anatomical adaptations	Behavioural adaptations	Physiological adaptations