4. Marine Center
Antarctica hosts an abundant array of animal life, despite its ice-covered terrain and barren plant life. There are lots of amazing wildlife living in the waters around Antarctica.
Krill and phytoplankton are some of the smallest forms of marine life the oceans, while whales are among the largest. There is an incredible array of amazing wildlife living, hunting, and hiding in the frigid Antarctic waters. Are they friends or enemies?
There are 17 species of penguins worldwide, but only seven of them are found in the Antarctic region: Adélies, Chinstraps, King, Emperors, Gentoos, Macaronis, and Rockhoppers. These flightless birds are the most numerous of all Antarctic birds.
Penguins are well adapted to the cold: a layer of oily, un-wettable feathers covers them and gives a distinguished, well dressed look. Underneath is a layer of soft down feathers and under that a thick layer of fat. This insulates penguins on land and keeps the wind off. Penguins are actually so warm that they fluff their feather to cool down!
Penguins have short feet which makes walking difficult (they toddle in an amusing way!) so - to ease their burden walking to and from the sea, they often establish a common path for everyone. This continuous use wears down the path and makes it easier to use.
Penguins are also well known for their swimming abilities: they can swim up to 30 miles per hour! Their short wings reduced to flippers are used for propulsion and their feet as a rudder; and their short, very densely packed feathers help in streamlining in water. Through the use of air sacs to protect their lungs, penguins can stay under water for 15 to 20 minutes and dive as deep as 275 feet (900 meters).
In the water, penguins typically feed on krill and fish. Feathers black above and white underneath are a perfect disguise in the sea. Short, sharp beak helps them catch the prey (and is also very useful in attacking nosy scientists and tourists!) and backward pointing barbs on tongue stop it from escaping.
Most penguins spend the majority of their life at sea and return to land to reproduce. Penguins breed in colonies (up to half a million birds!) – and these are usually very loud, raucous, busy and smelly affairs. All but king and emperor penguins build a nest, though they are usually only a simple pile of stones that are continually stolen and swapped between the members of a colony.
Many species lay two eggs, though it is rare that two chicks are raised, if food is short it will be fed to the biggest and strongest only. Male and female parents share egg and chick duty. Emperor and King penguins keep the egg and then the young chick on their feet covered by a brood pouch until they are large enough to regulate their own temperature. Chicks are fed regurgitated fish and krill.
Penguins main predators in the ocean are leopard seals and killer whales – but exceptional vision in the water help penguins avoid the danger. On land their arch enemy is skuas (large birds) which snatch eggs and penguins chicks from nests.
Watch emperor penguins huddle and hatch!
Squid and Octopus
The Squid is a soft-bodied invertebrate (animal without a backbone) closely related to the octopus. The squid range in size from barely 2.5 cm up to 4 m! The biggest squid in Antarctica is Mesonychoteuthis, which has large hooks, as well as suckers, on its arms and tentacles for capturing prey.
Squid have a large mantle/head (with a large brain), eight arms with suckers, two longer feeding tentacles, a beak, a large head, two large eyes, and two hearts. Squid can change the color of their skin to mimic their environment and hide from predators.
Squid move by squirting water from the mantle through the siphon, using a type of jet propulsion. When in danger, squid squirt a cloud of dark ink in order to confuse their attacker and allow the squid to escape. Squid reproduce by releasing eggs into the water. Some squid eggs are free-floating, others are attached to seaweed or to the ocean floor.
Squid eat mainly fish and crustaceans, although they are also known to be cannibalistic and may feed on each other, especially when caught in nets. These fast-moving carnivores (meat-eaters) catch prey with their two feeding tentacles, then hold the prey with the eight arms and bite it into small pieces using a parrot-like beak.
Many vertebrate predators depend heavily on squid, which is second only to krill as a food source in the Southern Ocean. Animals such as the grey-headed albatross and the sperm whale (the largest of the toothed whales) feed almost entirely on squid.
The octopuses are less well known and despite the fact that they are very common, there are undoubtedly many species in Antarctic benthic ecosystems which are currently unknown to science.
Fish in the Antarctic are important components of the marine ecosystems. They are major prey for higher predators, including toothed whales, seals and seabirds.
The Antarctic fish fauna is unusual in being dominated by the radiation of small number of groups. The most striking radiation is that of the so-called Antarctic cods (not related to true cods) the Notothenioids, which dominate the continental shelves. However in deeper waters there are also significant radiations of snail-fishes (Liparidae) and eel-pouts (Zoarcidae).
The Antarctic fish fauna contains the unique vertebrate group the Channichyidae or icefish (so called because of their pale coloration). These fish are the only group of vertebrates which have no red blood pigment (hemoglobin). Oxygen is transported instead in solution in the blood plasma. The mackerel icefish (Champsocephalus gunnari) is important prey for Antarctic fur seals, and is the subject of a closely regulated commercial fishery.
Antarctic Nototheniid fish living in close proximity to ice have evolved a glycoprotein antifreeze in their body fluids to prevent freezing.
Fish in the Southern Ocean have been or are subject to commercial exploitation. Among the other varieties of fishes, the most hunted are the Patagonian tooth fish, resulting in a decrease in the number of albatrosses and petrels every year. Fishing can easily be considered one of the favorite pastimes at Antarctica.
Each spring, over 100 million birds breed around the rocky Antarctic coastline and offshore islands. These include albatrosses, petrels, skuas, gulls and terns.
Albatrosses are large seabirds. They range widely in the Southern Ocean and the North Pacific.
Albatrosses are among the largest of flying birds, highly efficient in the air, using dynamic soaring and slope soaring to cover great distances with little exertion. They feed on squid, fish and krill by either scavenging, surface seizing or diving. Albatrosses are colonial, nesting for the most part on remote oceanic islands, often with several species nesting together. Pair bonds between males and females form over several years, with the use of 'ritualized dances', and will last for the life of the pair. A breeding season can take over a year from laying to fledging, with a single egg laid in each breeding attempt.
Of the 21 species of albatrosses, 19 are threatened with extinction. Numbers of albatrosses have declined in the past due to harvesting for feathers, but today the albatrosses are threatened by introduced species such as rats and feral cats that attack eggs, chicks and nesting adults; by pollution; by a serious decline in fish stocks in many regions largely due to overfishing; and by long-line fishing. Long-line fisheries pose the greatest threat, as feeding birds are attracted to the bait, become hooked on the lines, and drown. Identified stakeholders such as governments, conservation organizations and people in the fishing industry are all working toward reducing this by catch.
Black-browed albatross are mostly white with yellowish-orange webbed feet, grey highlights and a bright yellow beak. A conspicuous black eyebrow gives them their name. Of the 24 albatross species, the black-browed albatross is one of the smallest. The adult bird is 80-95 cm in length, with a wing span of 210-250 cm and weighs 3-5 kg.
Black-browed albatross generally have the same breeding partner each season. They nest on terraces on top of coastal tussock-clad cliffs or steep slopes up to 300m above sea level. The nest is a solid pillar of mud and guano with some tussock grass and seaweed incorporated, and is re-used annually. A single egg is laid in early October. Chicks are covered with pale grey down, and are fed by both parents. Fledged young birds leave the nest between mid-March and early April.
Black-browed albatross fly fairly low and take food from the sea surface or just below, occasionally plunging from heights of up to nine meters. They eat mostly krill and fish, with some cephalopods, salps and jellyfish.
Birds may travel long distances to find food - foraging trips can take several days and extend hundreds of kilometers.
Black-browed albatross are long-lived birds, living 30 years or more, and have a strong bond to their colony of birth. However, their population is endangered.
Wandering albatross have a white head, neck and body, a wedge-shaped tail, and a large pink beak. Juveniles have mostly dark plumage, which gradually whitens with age.
Wandering albatross are found right across the Southern Ocean, including Antarctic, subantarctic and subtropical waters.
Wandering albatross breed on subantarctic and Antarctic islands; and young birds will remain at sea for 5 to 10 years before returning to their natal island to breed.
Wandering albatross breed only once every two years, and the task of incubating the half-kilogram egg and rearing the chick is shared by both parents.
Their diet consists of fish, cephalopods, jellyfish, and on rare occasions crustaceans. They also eat penguin and seal carrion.
Chicks may consume up to 100 kg of food during their rearing period, which lasts for approximately 300 days.
Foraging trips of wandering albatross can last for 50 days at a time but tend to be much shorter during the breeding season.
Antarctic petrels have chocolate-brown and white wings with broad white trailing edges. The tail is white with a brownish-black tip. They are a medium-sized petrel with a 100-110 cm wing-span, with an average mass of 675 g.
Antarctic petrels are mainly confined to the vicinity of the pack-ice, icebergs, ice floes, Antarctic seas and the Antarctic continent. Flocks are characteristically seen sitting on the ridges of icebergs. In late winter, they are occasionally recorded in Australia and New Zealand.
Antarctic petrels are gregarious at sea and roost on icebergs in flocks comprising thousands of birds. Breeding colonies range from a few nests to more than 200,000 pairs. At Haswell Island, the mean distance between nests was 1 m, and the minimum was 0.3 m.
The population is believed to be stable and is believed to be unaffected by human activities.
Antarctic petrels return to their nest in October to November and lay one elongated ovoid egg. They usually nest in clefts, crevices and on ledges on sloping rocky cliffs in snow-free areas. The incubation and nestling periods are 45-48 days and 42-47 days respectively.
Fledglings from the same colony may remain together in flocks. Two chicks banded in the same colony were recovered 6 years later, 780 km from the colony.
Hatching success ranges between 70 and 90% at colonies studied at the Haswell Islands and the Windmill Islands. Egg loss was mainly due to eggs rolling out of nests and subsequently freezing. Egg predation by south polar skuas also occurs.
The diet of Antarctic petrel consists of krill and other crustaceans, euphausiids, pteropods, amphipods, cephalopods and small fish.
Subantarctic skuas have grey-brown or dark-brown wings with conspicuous white patches, a wedge-shaped tail, and a black, short heavy bill.
Subantarctic skuas have a far ranging distribution and can be found from the subantarctic to as far north as the subtropics, including Australian, New Zealand, South African and South American coasts. Small numbers of subantarctic skuas have been observed foraging at Antarctic islands, but they do not breed there.
Although most adult birds leave their colonies during winter, on some islands off the coast of New Zealand, a large proportion of the population will stay near the colonies all year round.
Subantarctic skuas breed during summer months and will typically lay two eggs. They will often nest on elevated grasslands or in sheltered rocky areas adjacent to penguin colonies. They will defend their territories vigorously against all intruders including other skuas and petrel. Some birds choose not to nest in the colonies, but will establish solitary nesting sites.
The estimated lifespan of subantarctic skuas is approximately 11 years.
Subantarctic skuas scavenge and predate upon other seabirds and their young, eggs, fish, mollusks, crustaceans and small mammals. Their diet is very broad depending on season and their locality.
South polar skua
The south polar skua is a large bird that grows to 53 cm in length.
It breeds on the Antarctic Continent and is a winter visitor to Australia. It has been recorded as far north as Greenland and the Aleutian Islands.
South polar skuas arrive at their breeding colonies in late October to mid-December. Their nests are a shallow depression on the ground and are generally found in sheltered locations on rocky outcrops, moss covered cliff sides or valley floors.
The eggs hatch in late December to late January after an incubation period of 24-34 days.
During the summer months, south polar skuas prey on eggs and young of Adélie penguins near the coast, while other skuas feed solely on fish and krill. South polar skuas are often seen following ships at sea.
Many skuas nest in close association with their prey. Southern giant-petrel and other skuas are infrequent predators on unattended nests and wandering chicks. Some eggs and chicks are lost each season to exposure.
Antarctic tern adults are approximately 40cm in length and have a wingspan of 80cm. The bill is bright red and the feet and legs, orange/red. The head is black during the summer, but in the winter months it is streaked with white.
Antarctic terns breed at Tristan da Cunha, Gough Island, Iles Kerguelen, St. Paul and Amsterdam Island, South Georgia, South Sandwich Islands, South Orkney Islands, South Shetland Islands, the Antarctic Peninsula, some New Zealand subantarctic islands, Macquarie Island and Heard Island.
Antarctic terns return to colonies in September and October. They are loosely colonial birds, rarely nesting with more than 40 widely-spread nests in any one locality.
Up to three eggs are laid in a shallow pebble- or shell-lined scrape on the ground, between October and January. The nests are difficult to see as the eggs and chicks are highly camouflaged.
Fledging of the chicks occurs between January and May. The parents attend their young for several weeks after fledging, occasionally feeding their chicks.
Antarctic terns are gregarious, fishing in flocks of up to several hundred birds just beyond the surf zone. They feed on small fish and various crustacean. Antarctic terns also scavenge in the intertidal zone for stranded littoral organisms.
Adult Antarctic terns co-operate to defend their colonies. However, skuas and kelp gull still occasionally manage to take eggs or chicks from unattended nests in colonies.
The species name is thought to come from the Dominican order of friars who wore black and white habits. Kelp gull have a white head, neck, underbody, rump and tail. The saddle and upperwing is slate-black with a white leading edge. The wingspan is 106-142 cm. The yellow bill has a rounded red sub terminal spot at the gonys??.
Kelp gull are broadly distributed in the subantarctic to subtropical regions, where sea surface temperatures range from 0° to 23° C. They can mostly be seen off the New Zealand coasts and islands, and along the south and south-east Australian coasts.
Kelp gull nest on beaches, among rocks, grassy headlands, ledges, glacial moraines and offshore islets. The shapes and materials of the nests vary due to location. They construct bowls or conical mounds or shallow scrapes in sand with grass, seaweed, sticks, shells and debris.
In the subantarctic, Kelp gull lay three eggs in November to December. Incubation and fledging periods are 23-30 days and 45-61 days, respectively. Parents sometimes continue to feed their chicks after fledging.
Kelp gull prey on and scavenge mollusks, fish, crustaceans, other seabirds, and even their own chicks and eggs. They are opportunistic, and their diet varies with season and among localities depending on the availability of food.
Seals are one of the few groups of marine mammals that live in the Antarctic.
There are two natural groups of seals, true (earless) seals and fur seals which have small flaps over their ears, and are related to sea-lions.
Six different species of seals live in Antarctic waters: Ross, Weddell, crabeater, leopard, fur and elephant seals. Fur seals are the smallest, with adult females weighing only 150 kg, while male elephant seals can weigh 4000 kg.
Four of these species are ice-habitat specialists, breeding on the sea ice in spring. Leopard and Ross seals tend to be solitary, whereas Weddell and crabeater seals form breeding groups or colonies.
The other two species – Antarctic fur seals and elephant seals – are both found north of the pack-ice zone and breed in dense colonies on beaches. Here, dominant males (bulls) maintain harems of females (cows). During the breeding period, competition for the harems is intense, so the bulls will not leave their territory to find food. Instead they rely on blubber reserves.
The smallest of the Southern Ocean seals are fur seals, while the largest are elephant seals. Seals are carnivorous and, depending on species, eat fish, squid or krill. The leopard seal will also eat penguins and other seals. Seals can dive to more than 600 meters in search of food and have specially adapted eyes for underwater vision in low light levels. While underwater, seals call to one another, and this can sometimes be heard above on the ice.
Seals spend much of their time under the sea ice in Antarctica, experiencing the relatively 'warm' sea temperatures. No matter how cold the air temperature is, the temperature of the sea is relatively constant, varying from only 1.8 to 1ºC around Antarctica.
Seals catch most of their prey under water, but spend some time on land or ice floes giving birth, raising their young and basking in the sun. On land they are quite ungainly but in the water they are very graceful and are excellent swimmers. Seals are well adapted to cold polar environments with thick blubber layers that act both as a food reserve and insulation. Most seals also have a layer of fur, giving additional insulation on land.
Antarctic seals have no native terrestrial predators and therefore behave very differently from the northern hemisphere seals. They show little fear of humans.
Studying seals is not always a straightforward process. Crabeater, Ross and leopard seals are very difficult to find as they breed on the ice in a different location each time. Biologists have started to overcome this problem by placing radio transmitters on seals to send signals which are tracked via satellite. Unfortunately the seals molt each year, so the maximum information biologists can obtain by this process is limited to only one year in the life of the individual animal.
These animals range in size from porpoises that are a little over a meter long, right through to the largest animal that lives on earth, the magnificent blue whale which can grow up to 24 meters and can weigh 84 tons.
Whales have undergone such extraordinary evolutionary changes in adapting to life in the oceans that it is hard to see what their ancestors might have been. By tracing through the fossil record we can now see that whales have evolved from much smaller land-based mammals that entered the water over 50 million years ago.
The general term 'whale' usually refers to the 'great whales' which includes the largest of the toothed whales, the sperm whale of Moby Dick fame, and all of the large baleen whales that were once hunted almost to extinction.
Cetaceans are divided into two broad groups; those with teeth, the toothed whales, and the filter feeders that catch small prey with special sieves in their mouths called baleen, the baleen whales.
Four species of toothed whales are found in Antarctica. Except for the sperm whale, they are much smaller than the baleen whales and weren't widely hunted. The other species are the southern bottlenose whale, the orca (killer) whale and the southern four tooth whale. They all have teeth which enables them to feed on larger prey such as fish and squid. Killer whales also eat penguins and seals, typically hunting in packs.
Six species of baleen whales are found in Antarctica, including the huge blue whale. Other baleen species are the fin, southern right whale, sei, minke and humpback. The name baleen refers to a hug, hairy plate in the whale's mouth, which acts as a sieve. This plate enables these whales to sieve or filter krill, plankton and crustaceans out of sea water.
Many Southern Ocean whales are migratory, heading to tropical waters during the Antarctic winter. Calves are born in these warmer waters, as the new born young would not survive in cold seas. The whales return south in the austral spring, following the receding ice edge; an area of high biological productivity, which provides a rich feeding ground. A young calf will accompany its mother for several years on the annual migration and females will not mate again until their calf is independent.
Whale exploitation to protection
The devastating exploitation of whales for the richness provided by their oils and other products led to much of the exploration of the globe by sea-faring nations.
Over 1.3 million whales have been taken from Antarctic waters this century. Although greatly reduced in numbers, six species of whales still live in Antarctic waters. It is estimated that there were over 225,000 blue whales before their exploitation; today there are less than 2000.
The whale then became the icon of the modern conservation movement as the plight of these animals was recognized. We now recognize and value the role these creatures play in healthy marine ecosystems and millions of people now have the memorable opportunity to see a whale 'up close and personal' as part of the new whaling industry; whale watching.
Did you know, that...
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