Blue whale
Physical description and related species
The biggest blue whale ever weighed was nearly 200 tonnes and over 30 m in length.
Distribution and abundance
Distribution: Blue whales, along with minke whales, venture further into the sea ice than other rorquals (such as the humpback and sei whales), and have been seen near 78°S in the Ross Sea.
Pygmy blue whales are never found south of 50°S, and feed off the southern Australian coast in summer. They grow to 'only' about 25 m.
Threats: Southern Hemisphere 'true' blue whales were reduced from around 225 000 individuals pre-exploitation to probably less than 2000 now. In just one area—South Georgia—30 000 blue whales were killed in the 1930-31 season alone.
Conservation status: endangered
Breeding
The breeding grounds of Southern Hemisphere blue whales are still unknown but are thought to lie somewhere in the deep oceanic waters of the tropical South Pacific, Atlantic and Indian Oceans.
A new born blue whale calf weighs 2.5 tonnes and can, in the latter stages of suckling, put on 100 kg a day.
Diet and feeding
A blue whale gulps up to 50 tonnes of water and krill in one feeding mouthful, but swallows only the krill.
'True' blue whales are one of the fussiest eaters in the Antarctic, usually eating only Antarctic krill (Euphausia superba).
Whale song
Blue whales off Sri Lanka have a song which consists of only four long, low notes.
Low frequency moans of blue whales, some of them lower than human hearing, can theoretically travel several thousand kilometres, and at close range are as loud as a jumbo jet taking off.
