In amazing contrast with the barren and seemingly endless ice covered plains and mountains that make Antarctic’s topside such an inhospitable place for most forms of plant and animal life, the frigid waters that surround the continent are nutrient rich, enabling marine life to thrive. There are crustaceans and fish, cephalopods and a stunning array of invertebrates, and plenty of marine mammals and birds to discover on a diving excursion to Antarctica, and new species are being discovered at a lightning pace. Let’s take a closer look at some of the creatures most commonly encountered around this ice-bound continent.
Krill
Why start with such a humble little creature? As it turns out, these silver sided crustaceans, which are close relatives of shrimp and prawns, are vital to the survival of most marine life in and around Antarctica – in fact, they are the continent’s keystone species. Feeding on zooplankton and phytoplankton, Antarctic Krill, or Euphasia Superba, swim in massive schools called swarms. Probably the most abundant of any type of marine life on earth, their biomass consists of an astounding 500 million to 725 million tons. These little animals grow to be about 6 centimeters long and can live for up to about six years. They spawn in January and March, close to the surface. Eggs sink into the abyss, hatching at a depth of about 3,000 meters before beginning a slow ascent back toward shallower waters. Incredibly slow-growing, these animals reach maturity at an age of two to three years.
Beneath the Arctic Ice, green plankton forms; clinging to the underside of the ice, it provides forage for the krill, which can be observed feeding. Some of the krill you’ll see while diving are bioluminescent.
Whales and Dolphins
At the opposite end of the spectrum are the cetaceans. Many species of whales can be observed in Antarctic waters; and while a few lucky visitors have had the good fortune to view whales from beneath the surface while diving or snorkeling at feeding grounds, most whales are observed from ships’ decks.
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Baleen Whales – Right Whales and Sei Whales can be observed feeding on krill swarms. These two species practice a unique method of capturing krill; they swim through swarms with their mouths open, half beneath the water and half above the surface. Other baleen whales, including Blue Whales, Fin Whales, Southern Right Whales, Minke Whales, and Humpbacks can be seen as well.
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Toothed Whales – Antarctica’s toothed whale population is fairly high. There are an estimated 200,000 Orcas living here, which never were of much interest to the whalers who hunted many other species. Southern Bottlenose Whales, which are migratory, can be seen on their summertime forays into the Antarctic region, and highly endangered Sperm Whales, which can grow to be 18 meters long, are encountered on occasion. Southern Fourtooth Whales are often seen as well; smaller and more elusive than many other whales, they form huge pods – an amazing sight!
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Dolphins – Only two species of dolphin are encountered in the Antarctic. The first, the Southern Rightwhale Dolphin, is a close relative of the Southern Right Whale, and is rarely seen. The second, the Hourglass Dolphin, lives all around Antarctica. Less than two meters long, these sleek little marine mammals have stunning black and white markings and, like their cousins worldwide, enjoy surfing waves made by ships’ bows.
Seals
Although there are 35 recorded species of seals living on the planet, only six of these call Antarctica home. Once heavily hunted, these animals have no natural predators other than Orcas, and are practically fearless, often simply yawning as groups of explorers photograph them.
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Weddell Seals – Commonly encountered in huge groups, these seals are sometimes found on inland fast ice all over the continent, although they prefer to dive to depths as deep as 300 meters in search of fish. Like many other seals, they maintain diving and breathing holes which they are happy to share with human visitors.
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Southern Elephant Seals – As large as fifteen feet long and tipping the scales at up to about 3,600 kilograms (7,900 pounds), these massive seals form colonies, usually with one huge male guarding a harem of about 50 females. Preferring rocky beaches to pack ice, these animals often lie one on top of another.
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Ross Seals – Seen much less often than other Antarctic seal species, these animals prefer to live their lives on heavy pack ice. While sometimes seen in Sub-Antarctic waters, these seals breed exclusively in Antarctica and are protected under the Antarctic Treaty.
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Leopard Seals – Often seen hovering around the edges of penguin colonies, and feeding on fish as well, these beautiful seals have grey coats with distinct leopard spots that give them their name. Growing to be about 11 feet long, they sometimes prey on smaller seal species.
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Crabeater Seals – Dining primarily on krill, these small seals do eat crabs and other crustaceans, along with a few fish and invertebrates. Usually solitary, they sometimes form small family groups, and can usually be encountered along the edges of pack ice. Perhaps it is because of their tendency to prefer their own company to that of their peers that these seals have managed to survive so well; despite their limited habitat, they are the most numerous of all seals and with numbers estimated at 30 million individuals, make up half the world’s seal population. Their only predators are Orcas and Leopard Seals.
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Antarctic Fur Seals – Hunted nearly to the brink of extinction, Antarctic Fur Seals are eared seals rather than true seals. Preferring Western Antarctica’s rocky shoreline, these animals are much less docile than their cousins and have been known to bite humans. They’re very fast, even on land, so be sure to respect their space if you encounter them.
Fish
There are many different types of fish living in Antarctic waters, some of which you’ll find in other areas around the planet. Some, such as cod, may be familiar to you. Others, like the Icefish, which has a form of biological antifreeze circulating throughout its body, may not be so easy to recognize. Most species found here are migratory, and some, like the Patagonian Toothfish, which is marketed as Chilean Sea Bass, are overfished and suffer from rapidly declining populations. Divers normally encounter fish in schools, particularly in areas where krill swarms offer easy opportunities for them to feed.
Invertebrates
Besides squid and octopus, some of which live at depths hundreds of meters below the surface, the Antarctic is home to a wealth of invertebrates including crabs and other crustaceans, beautiful basket stars, sea cucumbers, sea pigs, and even sponges. Sea butterflies and sea hedgehogs are seen here as well as countless others.
Birds
Although not technically marine life, birds are an important part of Antarctica’s ecology; there are an estimated 100 million birds or so living on the continent, mostly near shores where rocky outcroppings and access to swarming krill make nesting easy and food abundant. This icy world is home to six of the world’s seventeen penguin species, along with different petrel and tern species, albatross, and other seabirds. As you dive, particularly if krill are numerous, don’t be surprised if these winged beauties streak past you in the water.
As you enjoy your Antarctic expedition, be mindful of the fact that anything which is left behind here can cause problems for wildlife; things that are biodegradable in other parts of the world simply freeze and blow around here. Plastics, in particular, can cause a problem. Respect boundaries and enjoy the opportunity to photograph these magnificent animals; you are certain to come away with amazing images and memories that will last a lifetime.