Antarctic Seals

There are 35 different species of seals. However, only six types live in Antarctica. "The Antarctic seals belong to the group of marine mammals called Pinnipeds (fin-footed). This includes the Phocidae (true seals), Otariidae (fur seals and sea lions, or eared seals), and Odobenidae (walruses). In Antarctica, there is one eared seal - the Antarctic fur seal - and five true seals: southern elephant, Weddell, leopard, crabeater and Ross.
All seals are carnivorous, and except for the fact that their feet are flipper-like to accommodate an aquatic life style, they are very similar to the Carnivore order, which includes the cats, dogs, otters, bears, etc.

Many species of seals, including some of those found in Antarctica, migrate long distances during different seasons of the year. They gather on and around the pack ice and shorelines during summer months in order to breed. The females only give birth to one young. Because other seals disperse after the short breeding season, mating must take place soon after the females give birth.

The mothers' milk contains about 45% fat and 10% protein (compared to 4% and 2% respectively in cow's milk), and the seal pups grow very quickly. Most species are weaned in about two months. The males have little or nothing to do with the raising of their offspring.

While the fur seal and the true seal are fairly closely related, there are some important differences. Fur seals have external ears, their hind feet can be positioned beneath the body in order to walk or hop on land. By contrast, the true seal has no external ears, their hind limbs extend straight back in line with the body. Of all the differences, however, the most important is the composition of the fur. The fur seals are aptly named for their dense, luxurious coats. Their fur consists of two different types of hairs, guard hairs and under-fur, which are arranged in bundles. Each long guard hair is surrounded by up to 70 short under-fur hairs, which gives the animal a highly efficient protective layer of insulation against low temperatures. It also gives it a pelt which was once highly valued by people. True seals, rely primarily on a thick layer of subcutaneous oil-rich fat or blubber, to insulate their bodies from the intense cold. Their fur is not nearly so thick or luxurious.

SOUTHERN ELEPHANT SEAL

The southern elephant seal has a large circumpolar range which includes not only the Antarctic mainland and islands, but most of the subantarctic islands as well. This is the largest species of seal in the world, surpassing even the walrus in size. The males grow to 20 feet in length and can weigh as much as 4 tons. Females, though large, are much smaller than the males and grow to about 12 feet in length and 1 ton.

WEDDELL SEAL

This is the most southerly of the seals - and indeed the most southerly of all mammals - breeding as far sough as 78 degrees South. It is almost always found within sight of land in both summer and winter. The species was not discovered until 1823 when Captain James Weddell captured six specimens during his voyage to the South Pole.

CRABEATER SEAL

This is the most abundant seal in the world, totalling somewhere between 30 and 70 million. The adults of both genders are about the same size, growing to 9 feet in length with a weight of 500 pounds. It is quite common to see adults with prominent scars on their flanks or bellies caused by encounters with leopard seals, or perhaps killer whales. It has a pointed , rather dog-like snout and is often encountered resting on pack ice or ice floes.

LEOPARD SEAL

As its name suggests, this seal is a predator. It is the only Antarctic seal which regularly eats warm-blooded prey. A portion of its diet consists of penguins, but it also eats fish, krill, and even the young of other seals. The leopard seal has none of the cute appeal of the other seals, but despite it ferocious reputation there have been very few cases of unprovoked attacks upon humans. They are solitary animals and it is rare to see more than one individual in a given area. Leopard seals chase and catch penguins with great speed, often vigorously shaking their prey to break it into smaller pieces before swallowing it.

While our expedition was in Paradise Harbor, we had two curious leopard seals following our zodiac boats to and from shore, often coming a few feet from the side.

ROSS SEAL

The Ross seal is probably the least known of all the pinnipeds. It is a solitary animal and is quite rarely seen as it inhabits the thick pack ice along the fringes of the Antarctic continent. The Ross seal has very large and well developed flippers compared with other seals. The incisor and canine teeth are delicate, sharp, and re-curved for catching squid, its main source of food. It is very vocal, and one of its alternative names is 'singing seal.' Very little is known of its breeding habits. (Antarctic Primer pg 76-85)

Icebergs

I'm hoping that I still have students and teachers that are following the blog as I share out some of the educational postings. Today, I'm going to focus on Ice. Believe me, in Antarctica there is plenty of ice in all shapes and sizes. I use this picture from Wikipedia to demonstrate how much larger an iceberg is below the surface of the ocean.

Occasionally, huge pieces of floating shelf ice break loose and drift away in the currents. These pieces of ice are called Tabular Bergs or Tabular Icebergs, and can be enormous, perhaps hundreds of square kilometers in surface area, and may drift for years before melting or becoming grounded. These are not to be confused with regular icebergs, which break off from glaciers that reach the sea. Not all Antarctic icebergs are of such huge proportions. Some are much smaller, for icebergs are simply pieces of ice, large or small which have broken (calved) off the ice sheet, ice shelves, or glaciers, and float in the sea. By definition, however, an iceberg is suppose to measure more than 100 square meters (1,100 square feet) in area, and stand more than five meters (16 feet) above the surface.

Indications of an iceberg's history can be gleaned by observing its color (which depends on age, density and air content of the ice), or dark bands that reveal the presence of glacial moraines or volcanic ash, or its general shape and sculpturing. Sometimes horizontal or oblique water-lines at different levels show where the iceberg has melted and then tilted as it adjusts its center of gravity (AP pg. 32,33).

Most of the information I could find, including a presentation that was given to us the night before heading into Iceberg Alley, classifies icebergs into roughly seven categories.

1. Tabular - These are large with flat top resembling a huge tablet. Have usually broken away from ice sheets or an ice shelf

2. Non-Tabular - Often referred to all icebergs that are not tabular

3. Blocky - Flat topped and block shaped with steep sides

4. Dome - Rounded in the middle while tapering to the edges

5. Wedge - Top narrows to a pyramid point

6. Drydock - An iceberg eroding to the point that it forms and enclosure much like a harbor. Thus the name "drydock"

7. Pinnacle - Having one or spires, often resembling a castle.

Other terms used to classify ice at Antarctica:

1. Anchor ice - Submerged ice that is attached to the sea bed

2. Glacier - A mass of snow and/or ice moving from higher to lower ground. Sometimes a glacier can float out onto the sea

3. Pancake ice - a form of ice that consists of round pieces of ice with diameters ranging from a few inches to many feet in diameter

See if you can pick out and identify the different types of icebergs!

Antarctic Eco Tourism

A friend sent me this news article which is an interesting policy move from President Obama so early in his tenure.

http://www.foxnews.com/politics/first100days/2009/04/05/obama-calls-limits-tourism-antarctica/

The Southern Ocean

There is a tremendous amount of information that has written about Antarctica for those wanting to do some heavy reading. Much of the information I will be sharing is from a few different sources including my personal experience, pictures from our expedition, personal research on specific subject matters and the Antarctic Primer provided to each member of the expedition.

"The Southern Ocean consists of a broad band of generally turbulent water surrounding the continent of Antarctica. The northern limit of this ocean is at about 40 degrees South latitude. Westerly winds and the associated West Wind Drift, or Antarctic Circumpolar Current, are outstanding features of the Southern Ocean. They cause massive amounts of water to move constantly from west to east all around Antarctica. This involves water from the surface down to about 3,000 meters (9,900 feet) stretching over a distance of some 24,000 kilometers (14,200 miles).

It has been estimated that on average some 130 million cubic meters of water per second are continuously on the move, four times that of the Gulf Stream, and 400 times that of the Mississippi.

A ship sailing south to Antarctica will encounter a sharp drop in temperature between 49 degrees and 55 degrees South latitude. At that point one can usually detect subtle changes in both the ocean and the atmosphere. If the weather is calm there may be a sudden fog bank, a line of turbulence, and/or concentrations of feeding seabirds. This delineates the Antarctic Convergence, a zone that surrounds the continent." (AP pg.15)

On the expedition, it was communicated when we were heading into the Antarctic Convergence. We experienced a definite drop in temperature and associated fog which can be associated with a change in atmospheric conditions.

A few of us commented on the change we could see and feel regarding the changes in the atmospheric pressure and climate change. I commented in an earlier blog on how the foggy conditions also contributed to the mystic that surrounds Antarctica.

Obviously, one of the dangers of the Southern Ocean are the large icebergs.

ANTARCTICA

My first educational posting will focus on the continent of Antarctica and King George Island of the South Shetland Island chain. Our expedition, departed Ushuaia, Argentina and we traveled by ship through the Drake Passage for 2.5 days. The Drake Passage is considered some of the most dangerous waters to navigate in the world. If you view my postings on the Drake you will understand why.

Our first stop was on King George Island, 684 Nautical miles away from the southern tip of South America. It is located at 62˚23’S 58˚27W between the Drake passage on one side and Bransfield Strait on the other. In 1819, the island was named by British explorer William Smith in honor of King George.


We observed both chinstrap and Gentoo penguins playing on the shore as we landed. Many penguins had migrated north in preparation for the winter months.

King George Island is the largest of the South Shetland Islands off the coast of the Antarctic peninsula. The surface of the island is made up of volcanic rock and 90 percent is covered in Glacier. Since first claimed by Britain, Chile and Argentina have both laid claims to the island. Most countries do not recognize Chile and Argentina's claim and reserve the right to make claims throughout Antarctica.

Many countries have laid claim and established bases on King George Island. This is due to better weather conditions, convenient airstrip accessibility and waters that do not freeze during the winter months.

The famous Russian base of Bellingshausen Station was where we landed our zodiac boats. The base is fairly large and is manned by roughly 22 people throughout the year. While there, we met the only female at the Russian base who was filming a documentary of life at the station. She had planned to be there for an entire year. At Bellingshausen Station, the Russians have also established what is considered one of the southernmost Church's in the world. The Russian Orthodox Trinity Church which was brought piece by piece from Russia.

Other countries who have established bases on King George Island are: Argentina, Brazil, Chile, China (the base is call the Great Wall and the Chinese members of our expedition were allowed to visit), South Korea, Peru, Poland and Uruguay.

Robert Swan's 2041 organization was the first independent group to establish a private ebase (e-learning) on King George Island. In 2009, this base went live 365 days a year through the use of renewable energy.

By definition (Heritage Dictionary) "Antarctica is a continent lying chiefly within the Antarctic Circle and asymmetrically centered on the South Pole. Some 95 percent of Antarctica is covered by an icecap averaging 1.6 km or 1 mile in thickness. The region was first explored in the early 1800s, and although there are no permanent settlements, many countries have made territorial claims. The Antarctic Treaty of 1959, signed by 12 nations, prohibited military operations on the continent and provided for the interchange of scientific data. "

According to Wikipedia, "Antarctica is the Earth's southern most continent, overlying the South Pole. It is situated in the Antarctica region of the southern hemisphere, almost entirely south of the Antarctic Circle, and is surrounded by the Southern Ocean. It is the fifth-largest continent in area after Asia, Africa, North America and South America.

Antarctica is the coldest place on Earth. The coldest natural temperature ever recorded on Earth was -89 degrees Celsius or -128 degrees Fahrenheit at the Russian Vostok Station in Antarctica on 21, July 1983. For comparison, this is 11 degrees colder than subliming dry ice. Antarctica is a frozen desert with little precipitation; the South Pole itself receives less than 10 centimeters or 4 inches per year, on average. Eastern Antarctica is colder than its western counterpart because of its higher elevation. Weather fronts rarely penetrate far into the continent, leaving the center cold and dry."

One of the key differences between the Arctic and Antarctic, is that Antarctica is a continent. It is made of 5.4 million miles and is covered by an icecap. The Arctic is not a continent, but a floating icecap. In the winter months, Antarctica swells to 10.2 million square miles.

Check back soon for another educational posting!