Scientific name: Balaenoptera musculus
Order: Artiodactyla (Cetacea)
Sulphur bottom whale
The Blue Whale is the largest animal that has ever lived on the planet, (even larger than the biggest dinosaurs).
Underwater they look blue, but out of the water they are more grey than blue and have small spots over the back. They have a broad flat head and a long body, and a small dorsal fin set ¾ back to the tail. Blue Whales can reach lengths of between 20 to 30 metres, the same size as a jumbo jet.
They have the largest blow of all whale species, reaching up to 10m in height.
Habitat and distribution
Blue Whales are seen over deeper continental shelves and canyons over deep water so they can dive down to catch their prey.
They occur in all major oceans of the world, and are strongly migratory between summer feeding areas in higher latitudes (of both hemispheres) and tropical and sub-tropical natal areas. Information on Blue Whale distributions is far from complete, in part due to the scarcity of the animals.
In the northern Atlantic, Blue whales are most numerous on the western continental shelf slope, but small populations do survive in eastern waters, and are occasionally seen in Biscay and off SW Ireland. Most summer records are from Iceland and further north.
Blue Whales are a solitary species but have been observed in small pods or as a parent and calf.
They blow every 10 to 20 seconds for a few minutes before diving back under and can stay underwater for 5 to 20 minutes. When coming to the surface, they surface at shallow angles before its back is in view. Then it rolls at a gentle angle, with the dorsal fin appearing before the arched tail stock.
Blue Whales sometime breach, but very rarely is it seen, and have been observed lunge feeding.
Confusion with other species
The combination of size, body colour and tiny dorsal fin set well back should make the Blue Whale unconfusable. However, distant powerful blows and glimpses of apparently huge bodies should not be assumed to be Blue Whale; Fin Whales can also appear very large.
In the past, blue whales were targeted by whalers for their oil which nearly drove them to extinction. During the 1900s to mid-1960s, about 360,000 whales were hunted. However, in 1966, they received worldwide protection and numbers are increasing. It is now believed there are between 10,000-25,000 blue whales in the world - a significant increase in the past three decades.
Due to their size, they do not have many predators. However, the main threats to blue whales are strikes by large ships, and pollution of the seas which can lead to have a lowered immune system.
The Blue Whale has a heart as large as a small car and blood vessels that a small child could swim through.
'Hope', a 25.2-metre-long blue whale skeleton replaced 'Dippy' the Diplodocus dinosaur in the Hintze Hall of the Natural History Museum in 2017.