There isn't much life in the Antarctic. Because the continent is almost entirely covered by ice and snow, there's no real room for plants to grow. There are a few mosses and grasses that survive in the harsh conditions, and two flowering plants. Otherwise, plant-life is nearly nonexistent on land.

The water is a different question: Phytoplankton are able to survive in the cold waters, and get their energy from the sun. Krill eat the phytoplankton, and apart from some zooplankton and bottom-dwelling creatures, that's basically the summary of herbivorous Antarctic creatures; everything else is a predator.

Here's a quick overview of four of the most prolific hunters on Earth's southernmost continent:

1. Seals

There are four types of seals that live in the waters surrounding Antarctica: leopard, crabeater, Weddell and southern elephant. All seals are fairly slow predators that hunt by waiting in places their prey is likely to appear. Most of them are unlikely to pay humans much mind at all - except for the leopard seal.

This seal, named for its characteristic spots, has been known to become aggressive with humans in small boats. They're fierce predators and are perfectly happy to eat anything. Although they don't attack humans often, it's best to give leopard seals a wide berth.

2. Whales

During the summer, Antarctic waters are full of many different types of whales looking to eat fish, squid, penguins and plankton. Killers whales are one of the species travelers might be able to spot on their trip. These are the most aggressive and ambitious hunters, as their sights are set on seals, sea birds and other whales. They're perfectly capable of taking down creatures that are much larger than they are, provided they hunt in groups.

Despite being aggressive toward other wildlife, killer whales aren't known for attacking humans in nature. Some killer whales in captivity have attacked their trainers, but generally speaking, humans aren't at any particular risk around these creatures.

Other whale species that travel south for the summer include humpback, orca and the largest animal on earth, the blue whale.

3. Penguins

The world's favorite awkward Antarctic creature, penguins mostly eat krill and very small fish. They spend most of their time in the water, but usually come on land to mate and raise their chicks.

Although Antarctic penguins don't think of humans as a threat or a meal, it's still best to exercise caution when around them. They're not shy around people, and may come right up to you - still, they can and do bite, so it's wise to treat them the way you would any other wild animal.

• Meet the penguins of Antarctica
• The King Penguin
• Fun facts about the penguins of Antarctica

4. Bugs

Antarctica's only true land predators fall solidly under the "creepy-crawly" category. These tiny bugs are fascinating because they're the only creatures that can survive on Antarctica's surface. They handle the winter by going into hibernation - they stand perfectly still, and their blood works to keep them from freezing. This mechanism allows them to make it through to summer, when they get back to eating the smaller bugs.

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Other animals in Antarctica

While no land animals live in here, the surrounding ocean is home to an array of animals that visitors on Antarctica cruises might not expect to see. From albatross to leopard seals to the blue whale, these cold seas brim with life.

Albatross

Distinguished by its atypical combination of a white head and black brow, the black-browed albatross is a stunning sight. These giants have the longest wingspan of any bird - up to 11 feet. Since they're rarely seen on land, albatrosses use their wide wings to ride the ocean winds and sometimes glide for hours without a flap of their wings. They drink saltwater too, so they don't need to worry about stopping on land, except to mate and raise their young. Many of these winged wonders can live as long as 50 years.

Orcas

Yes, these are killer whales, but they're not part of the whale family. Instead, the toothed mammal is largest member of the dolphin family and is highly social, traveling in groups called pods. Like dolphins, orcas use echolocation - bouncing sound off of objects to determine their location - to feed on fish, squid, birds and other animals. When born, a calf weighs up nearly 400 pounds and measures up to 7 feet in length.

Rockhopper penguins

Some animal lovers might say that a visit to Antarctica is not complete without spotting a penguin. The rockhoppers are one of the more ornate penguins, decorated with yellow eyebrow used to attract a mate. Normally, these ice-loving birds stand 16 to 18 inches tall and are found swimming between sub Antarctic islands. Watch them shake their heads extremely fast so their yellow brow looks like a halo.

Leopard seal

The leopard seal is named for its spotted fur coat. Famous for their fierce nature, these animals are one of the primary predators in Antarctica, using their powerful jaws and long teeth to hunt fish, squid, penguins and even other seals. If voyagers on the cruise in Antarctica are lucky, they might catch a glimpse at a seal snare a bird as it enters the cold waters. Fascinatingly, leopard seals have no ear flaps, but rather hear from the inside.

Blue whales

As the beasts of the sea, blue whales grow as long as 100 feet and weigh more than 120 tons. In fact, their tongues alone can weigh as much as an elephant. While blue whales look true blue underwater, if any cruise critics see them breach, they'll notice that the mammal is more a mottled blue-gray. Their underbellies, meanwhile, take on a yellowish coloring due to the millions of microorganisms that live on their skin.

Krill

At the near bottom of the food chain are krill: small, shrimp-like crustaceans that basically fuel the engine of the earth's marine ecosystems. Though you might never see these tiny swimmers on an Antarctica cruise, they will be swimming underneath the ship, feeding on microscopic phytoplankton. As one of nature's humorous ironies, the largest animal ever to roam the earth, blue whales, survive off of krill.

Adélie penguin

Adélie penguins spend the winter in the seas surrounding the Antarctic and the rest of the year on the many small coastal islands. These cute creatures are actually amazing divers, and have been known to plunge as deep as 575 feet in search of food. That's not even the extent of it - in fact, Adélies may travel 185 miles round-trip to find a meal.

Off of the shores of the southernmost continent of Earth, voyagers can encounter a range of eye-capturing animal life.

Read more about Antarctica:

• Changing climate in Antarctica
• 15 interesting facts about Antarctica
• 9 reasons to travel to Antarctica