Introduction to Polar Sea Life Arctic Antarctic M

Introduction to Polar Sea Life: Arctic & Antarctic M. L. Anderson, 2009

Contents n n Polar Seas North – – – n The Arctic Sea Ice Arctic Life South – The Antarctic – Antarctic Life

n n Although the cold is intense, at the edges of these zones, there is a great diversity of life. The ice can take many colors and hues and can be found lying flat, or in any shape imaginable, as the sheets of ice move and are thrust in all directions. Polar Seas

Polar Seas n n Along with blistering cold and storms, polar regions have periods of calm and some warmth. In the summer, they have 24 hours of sunlight and in the winter there are months of darkness and bitter cold.

Differences Between Polar Regions Arctic n n n A frozen ocean surrounded by the land masses of America, Eurasia and Greenland. The Arctic Ocean is colder than the Southern Ocean water. The Arctic is significantly warmer than the Antarctic n n n Land animals can cross the ice sheets during the winter. A continent of rock with a thick ice-cap surrounded by the Southern Ocean is warmer than Arctic Ocean water. Antarctica is significantly colder than the Arctic. Land animals cannot reach Antarctica because it is remote.

North: The Arctic n n n Moderate temperatures of n 10 o. C (50 o. F) can be reached in the summer and only remote places like Siberia can reach -50 o. C (60 o. F) in the winter. The Arctic Ocean is almost entirely covered by a layer of ice several meters thick. It is surrounded by the northern fringes of N. America, Greenland Eurasia. These surrounding land masses affect the climate dramatically by absorbing much more of the sun’s radiation than ice does.

Arctic North n n Greenland is somewhat analogous to the Antarctic plateau. It is high and cold and has glaciers streaming down to the sea. As it is 90% smaller than the Antarctic plateau, its impact is less. The coldest places are in Greenland Siberia, far from the warming influences of the ocean.

Arctic Sea Ice n n Sea ice is a unique feature of the polar oceans. Its extent and thickness vary with the seasons. Ice is mainly formed during the winter months and melts in summer. In the Arctic, about 50% (7 million square km) of the winter sea ice melts during the warmer months. Typically, the thickness of "level" sea ice is 2 to 4 m.

Arctic Sea Ice n n n When sea ice forms, small spaces between the ice crystals remain and are filled with a salty solution called brine. Thus, sea ice consists of a mixture of ice crystals and brine channels, which form a 3 -D network of tubes with diameters of a few micrometers to several cm. A sympagic (ice-associated) community has adapted to the variable conditions in this matrix.

Arctic Life n n The Arctic Ocean is bordered by shallow continental shelves fed by rivers and mixed by currents. In the spring, phytoplankton (i. e. : diatoms) blooms. Diatoms are a major component of plankton, freefloating microorganisms of marine or freshwater environments. These diatoms sustain the invertebrates that live within the sea ice. Many also cling to surfaces such as aquatic plants, mollusks, crustaceans, and even turtles.

Diatoms n n n Diatoms are abundant in both freshwater and marine ecosystems. It is estimated that 20% to 25% of all organic carbon fixation on the planet is carried out by diatoms. This is possible because they contain chlorophyll. They are also a major food resource for marine microorganisms and animal larvae, and are a major source of atmospheric oxygen.

Foundation of North Arctic Life Brine Shrimp eggs Brine Shrimp Brine shrimp tunnels in sea ice. n n Copepods, a shrimp-like crustacean (brine shrimp), are the base of the Arctic food chain, thus a critical component of the marine ecosystem. They are the equivalent of Antarctic krill and feed on phytoplankton.

Arctic Benthic Life n n n Photo courtesy of v. Juterzenka, Piepenburg, Schmid A rich benthic community is located in the Arctic. Feather stars, basket stars, sea cucumber (all echinoderms) and anemones prefer hard bottom as a substrate. These cold tolerant organisms are an important food source for walruses, sea otters, seals and sea lions.

More Arctic Life Common Periwinkle Sea Anemone n n n Sea anemones are cnidarians that are found in both cold and warm water, often attaching to rocks, hard surfaces or the sea bottom. They have cylindrical bodies that are surrounded by upward facing tentacles with stinging cells which kelp to kill prey and move it to the anemone mouth. n n Common periwinkles are small, edible sea snails. They are an algae grazer, but will feed on small invertebrates such as barnacle larvae. They feed by grazing along the surface on which they live, using their radula to scrape algae from rocks and grasses or from the mud in estuary or bay bottoms.

North Arctic Life

South: The Antarctic n n Antarctica is a continent which is covered with an ice cap. At one time it was the center of the supercontinent Gondwanaland.

South: The Antarctic n n The surrounding Southern Ocean is much larger than the Arctic Ocean. It is also warmer than the Arctic Ocean, as it is contiguous with the Pacific, Atlantic and Indian Oceans. Antarctica is completely isolated by the Ocean which no land animal can cross. Antarctica is much colder than the Arctic, as it is not warmed by any continents and is surrounded by a recurring barrier of sea ice.

Food Web What is the Trophic Pyramid? http: //www. castlefordschools. com/ n n The tropic pyramid shows the ratios of how much each level needs to consume to fulfill their daily needs. Herbivores (primary consumers) must consume a great deal of producers to get the nutrition they need while large carnivores need to consume a great deal less by comparison.

Primary Producers n n n Producers are capable of creating their own food by using sunlight and nutrients around them. These unique organisms are the basis of all food pyramids In the Antarctic, the primary producers are Phytoplankton, like diatoms. Primary producers (1○) become abundant for about 3 months of the year around December. They need Potassium, Nitrogen and Phosphorus to grow which become abundant during these months. Primary consumers feed directly on the producers while secondary and all above consumers feed on other consumers.

Consumers: Krill n n Primary Consumers (1○) are krill, and zooplankton. n Feed on Phytoplankton at surface at night and swim down deep (100 m) for protection during the day. Euphausia superba n All secondary consumers (whales, penguins, and some birds) feed on them. Antarctic krill are shrimp-like invertebrates that live in large swarms, sometimes reaching densities of 10, 000 – 30, 000 individual animals per cubic meter. They feed directly on phytoplankton, thereby using the primary production energy that the phytoplankton derive directly from the sun. http: //www. biosbcc. net/ocean/AAlife. h tm n

Antarctic Krill n Krill Distribution n n They are pink in color, grow to 6 cm (2. 4 in) long and weigh up to 2 g (0. 7 oz). They can live for up to 10 years. During certain times of the year, they congregate in swarms so dense and widespread that they can be seen from space. They are a key species in the Antarctic ecosystem and are probably the most successful animal species on the planet (@ 500 million tons).

n n Krill are often referred to as light-shrimp because they can emit light, produced by bioluminescent organs. These organs are located on various parts of the individual krill's body. These light organs emit a yellow -green light periodically, for up to 2 - 3 seconds. Antarctic Krill

n n Antarctic Krill n n Antarctic krill can scrape off the green lawn of icealgae from the underside of the pack ice. Most krill swim in an upside-down position directly under the ice. Krill have developed special rows of rake-like setae at the tips of the thoracopods, and graze the ice in a zig-zag fashion, like a lawnmower. One krill can clear an area of a square foot in about 10 minutes (1. 5 cm²/s).

Humpback Whales n n n Population is about 30 -40 thousand compared to 750, 000 - 2 Million before the 19 th Century Easy target because eating, mating, and calving close to shore lines and slow swimmers. Oil was used for lamp fuel, lubricants, candles, and base for soaps and perfumes.

Other Antarctic Marine Critters; Under the Ice

Other Antarctic Marne Critters Octopus Antarctic Jellyfish n n n Jellyfish are a predominant component of the macroplankton and nekton community in the Southern Ocean. Gelatinous carnivores are important components of the food web because they are a control mechanism for its structure. They feed on copepods, medusae, ctenophores, fish, larvae, and molluscs. n n Prey for a Pareledone octopus includes amphipods, polychaetes, fish, ophiuroids (brittle stars), the giant Antarctic isopod and the sea urchin. Predators of Antarctic octopus include the Weddell seal, southern elephant seals, blue-eyed shags, and the blackbrowed albatross.

Other Antarctic Marne Critters Feather Stars Seastars; Odontaster validus Sea stars are both filter feeders and omniverous. White Sea Star; Perknaster aurorae Mae West and Brittle Stars

Other Antarctic Marine Critters The Antarctic has an unusual Paleozoic-type ecosystem. n Many asteroids and ophiuroids feed on mobile prey like krill, shrimps, and fish. Sea Urchins n Antarctic faunas are often connected with deep-sea faunas. Sea urchins, echinoids, play the role of keystone organisms for many marine ecosystems. The role of deposit-feeding sea urchins in nutrient-deficient soft-bottom communities is not well understood but is probably of great importance for the energy flow in the deep sea. Anemone n

Staghorn Sponges n n Sponges are ancestrally primitive animals once considered plants. They have ostia: little pores that lead to channels that radiate through their bodies bringing food and fresh sea water for respiration. Cactus Sponge; Dendrilla antarctica

Sponges n n n Filter feeding uses specialized feeding cells, choanocytes, (collared cells) that have a central beating flagella ringed by small filaments. The flagella beats, creating a water current, and as the water flows past the ring of filaments, particles of food such as phyto (plant) and zoo (animal) plankton are captured. The nutrition garnered by the choanocytes is then shared with the other cells in the sponge body. Giant Volcano Sea Sponges; Scolymastra

Other Antarctic Marine Critters n Parborlasia corrugata worm Proboscus worm n Combination scavengers and predators, these worms are the vacuum cleaners of the undersea Antarctic. It has a voracious appetite and will eat almost anything; its diet includes sponges, jellyfish, diatoms, seastars, anemones, polychaete worms, molluscs (including the Antarctic scallop, crustaceans, and fish.

Antarctic Marine Life “Antarctic marine communities look like primeval communities from hundreds of millions of years ago because modern predators such as crabs and fish Steve Connor, Science Editor in Boston are missing, "

Ice Fish n n Chionodraco hamatus n n n These are the dominant fish found in the cold continental shelf waters surrounding Antarctica. They are 33 cm or larger (12 -29”) in length weighing up to 11 lbs. These fish lack a swim bladder, therefore most species are benthic or demersal (they dwell at or near the bottom of the sea). They eat krill, plants and crabs. They live around Antarctica in the spring and summer, then migrate north for the winter.

Ice Fish Channichthyidae n n They are able to survive the frigid temperatures of the Southern Ocean due to the presence of antifreeze glycoprotein in their blood and body fluids. They are also able to survive without hemoglobin in their blood due to the high oxygen content of the cold waters and because they absorb and distribute oxygen directly by the plasma.

South: Antarctic Life

Antarctic Predators Killer whales, sharks, polar bears, sea lions, leopard seals, walruses, eagles.

Baleen Whales Above: The baleen exposed on a whale corpse. n n Secondary Consumers (2○) These large mammals feed primarily on Krill Their numbers have decreased lately due to increased whaling (mainly by Norway and Japan) These giants of the sea are the prey of killer whales when they hunt in packs and occasionally sharks.

Humpback Whales n n n Coloring- black on upper side and black and white spots on under side. Length- 42 feet females and 40. 5 feet males. Weight- about 50 tons. Eat about 4400 lbs of plankton, krill, and small fish a day. Live in North Pacific, North Atlantic and Southern Oceans.

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