Changes in their environment and how animals adapt.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 upwelling at the Antarctic Convergence. Animals need to have a whole range of specializations to be able to take advantage of these conditions.
Emperor PenguinAnatomical Adaptations
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 Behavioural Adaptations 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 Physiological Adaptations 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 |
Weddell Seal
Anatomical Adaptations
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 waterand frequently under ice where light levels are very low Whiskers (vibrissae)that help the seals feel their way in the dark when catching prey Behavioural Adaptations Seals keep open breathing holes in the iceby 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 territoriesbased 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 Physiological Adaptations 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 KrillAnatomical Adaptations
Very fine filtering net or "basket" formed by 6-8 pairs of limbs that can capture phytoplankton down to 1 micrometer (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 Behavioural Adaptations 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 reaction in 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", you can probably guess why. Usually krill stay in deep water during daylight hours and come to the surface at night, this helps them to avoid predators Physiological Adaptations 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 (0.055s) 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 Blue WhaleAnatomical Adaptations
Baleen plates in the mouth instead of teeth.These are 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. The bristly edges are filters to collect the krill in the water they gulp in before swallowing them when the excess water has been ejected. 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, the water is pushed out by the enormous tongue and food filtered out by the baleen plates. A ridge in front of the blowholes (the two nostrils) which are located on top of the head.Pointing backwards means that they are not filled with water when swimming and being placed on top of the head makes it easy to breathe while lifting and exposing the smallest amount of the body possible. Huge tail fin the size of two dinner tables that provide the propulsion for swimming. The smaller forward fins are for changing direction and the small dorsal (mid-back) fin helps with stabilizing straight swimming. Behavioural Adaptations Blue 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. They feed continuously during the super-productive summer months and then live entirely on their blubber reserves for about 4 months during the breeding season in warmer waters. Not all individuals migrate however. 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. These sounds can travel underwater for as far as 500 miles (800 km). They are very low frequency sounds down to 14hz, below the hearing limit of humans. Usually found alone or in small groups of 2-4 individuals though occasionally and rarely in larger groups of up to 60 have been reported. Physiological Adaptations Adult 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 carries oxygen in the blood, but provides an extra in-situ store for longer dives exactly where it is needed. Metabolism is able to cope with extended periods of plenty where extensive feeding allows the build up of many tonnes of blubber (stored fat) which is then used up during extended periods of starvation. |