They are the largest animal ever to live on earth!

The maximum length recorded for a female Antarctic blue whale (the sub-species of blue whale that feeds in Antarctic waters), was 33.5m which is as long as a Boeing 737.  The maximum adult weight recorded is 190 tonnes, equivalent to approx. 38 African elephants! The pygmy blue whale, the sub-species commonly seen in Victorian waters, reaches 24m in length and 150 tonnes.

Blue whales may live for about 90 years.  Newborn blues weigh between 2.5 and 4 tonnes and increase in size by 30 times in their first year of life.  They belong to the rorqual (groove-throated) group of baleen whales (which includes Minke, Bryde’s, Omura’s, Humpback, Sei and Fin Whales).  Their jet black baleen plates can be up to 1m in length.

Blue whales feed by gulping large quantities of krill.  Recent estimates suggest that a blue whale weighing around 80 tons needs about 10-15 tonnes of food a day, which equates to millions of krill (Nyctiphanes australis).  They are capable of diving up to 500m in depth when feeding, but usually feed in depths between 40-200m in the Bonney Upwelling.

As specialist krill feeders, worldwide blue whales are usually found in upwelling or frontal zones with high productivity, such as the Bonney Upwelling.   Even in these productive areas, krill are patchy in their distribution. Blue whales search vast areas in search of krill ‘hot spots’ , and upon finding them, they will remain to feed until this resource is exhausted. It is likely that they remember areas where they have had previous feeding success.

We now think that if blue whales find a food resource that is far greater than the needs of an individual or small group, they will use their low-frequency calls to ‘call in’ their companions. Researchers call this ‘reciprocal altruism’, where favours will be returned.

Blue whales make the loudest sound of any animal (as low as 9Hz), with their low-frequency calls being detected more than 1000km away under ideal conditions.