Toothed whales
'Toothed' whales, which includes all the dolphins and porpoises, are agile and highly active. They feed on squid and fish, using echo-location to navigate and to find their prey. A distinguishing feature is that they breathe through a single blow-hole. Most, but despite their name not all, have teeth.
Killer whales
A pod of orcas, or killer whales, working together on a hunt is among Antarctica's most spectacular sights. Highly social, very fast (bursting up to 35mph), each pod of up to 50 whales has its own dialect of sounds. They are significant predators of seals and penguins, and also target sharks, fish, squid and sometimes other whales. The waters off the Antarctic Peninsula are among the best areas for seeing killer whales.
Dolphins
Orcas are actually classed as dolphins, but the more typical species in Antarctica is the bottlenose dolphin, which is widespread around the world, highly intelligant, usually social, and everyone's idea of what a dolphin should be. The distinctive hourglass dolphin is much more unusual, restricting itself to the southern oceans and around Antarctica. They love to ride the bow-waves of ships, so you may be lucky enough to find them travelling with you.
Sperm whale
Colossal sperm whales, the largest predator on the planet, roam all the oceans. Males, who can weigh up to 60 tonnes, come to hunt in Antarctic waters mainly targetting squid.
Baleen whales
The slow giants of the oceans, trawling the seas for krill and small fish which they filter in curtains of comb-like bristles that hang from their upper jaw. Huge gulps of water are taken into their mouths, strained for prey as the water is expelled, and the food swallowed. Another distinguishing feature of these whales is that they have two blow-holes, while toothed whales just have one.
Blue whales
The largest animal on earth today, and among the largest ever to have lived, blue whales are the oceans' true giants. They can be spotted at sea at considerable distances by their huge 12m high blows as they surface for each enormous breath. Females reach nearly 33m in length, weighing up to 180 tonnes. A massive prize for whalers, blue whale numbers have dropped to 10,000-25,000 individuals, with a slow recovery since hunting them was banned in 1966.
Humpback whales
Humpbacks are known for being the most active large whales, with spectacular displays of breaching as they jump and twirl from the water. Quite why is a matter for conjecture - perhaps to show leadership or signal to others, maybe to look around ('spyhop'), possibly to shake off parasites, or perhaps just for the fun of it. They also bash the surface with their tails ('lobtailing') or side fins ('flipper-slapping') primarily as signals to others. Other whales do these things too, but humpbacks are the masters.
In Antarctica they appear in the high summer when their food of krill is at its most abundant. Some individuals deliberately approach ships to put on a display.
Southern right whales
Whalers considered this species the 'right' whale to catch: found close to shore, slow moving, and floating when killed, with their rotund corpses yielding valuable oil, meat and whalebone in great quantity. They are found around the southern oceans, including off the Falklands and South Georgia, though seldom as far south as Antarctica itself. They are prone to large growths on their head and jaw, termed 'callosities', which turn white with whale lice in patterns that help biologists to identify particular individuals. They are highly acrobatic.
Fin whales
Second only to the blue whale in size, fin whales are sleek, slender and v-e-r-y l-o-n-g. They can make swift progress through the water, earning them the moniker 'the greyhound of the sea'. They are not given to much breaching or display, and prefer to travel on their own or in pairs in open ocean.