Blue whale

Balaenoptera musculus
Blue whale
Blue whale (Balaenoptera musculus) Photo: Mark Carwardine
Blue whale (Balaenoptera musculus) - Photo: Jack Ashton
Blue whale (Balaenoptera musculus) - Photo: Mark Carwardine

Appearance

Size: max 29-33m

Key features:
Enormous size
- Skin is blue-grey in colour and mottled
- Tiny fin in comparison to body size
- Blow can be up to 10m high and takes a few seconds to dissipate

The blue whale is the largest animal that has ever lived on earth, even larger than the biggest dinosaurs. They are the size of a jumbo jet, weigh as much as 2000 people, have a heart as large as a small car and blood vessels that a small child could swim through! They have the tallest blow of all whale species, reaching 10m in height. Contrary to the name, they are more of a grey than a blue, and have lighter small spots over their back. They have a small dorsal fin, set well back on their body; it is not visible at the same time as the blow hole.


Behaviour

The blue whale usually travels alone or in pairs. Young blue whales breach, older blue whales do not. When they dive they often raise their wide tail flukes above the surface. Although they are the biggest animal, they feed on one of the smallest animals in the ocean krill (like small shrimp). They need to eat 4 tonnes or more each day. This equates to around 4 million krill!

Distribution

Blue whales have a worldwide distribution some populations migrate between low-latitude winter breeding grounds to high-latitude summer feeding grounds.

Threats

Historically blue whales had avoided being hunted thanks to their huge size and fast swimming speed. However, after the explosive harpoon gun was invented they became a hunting target for meat, oil and other body parts. They were given protection in 1966 after their populations became severely depleted. Populations are starting to recover, however progress is slow given the slow reproduction rates of the animals. Blue whales don’t reach maturity until they are 7 years old and have one calf every 2 – 3 years. Today the primary threats are ship strikes, noise and chemical pollution.

Sightings Map

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  • Click on each icon on the map to find out the date, time, latitude, longitude, route, vessel, species, and group size seen for that species at that point.


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