Blue whale

Balaenoptera musculus

Appearance

Size: 24 - 30m

Key feature: Giant size and tall blow.

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, with 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. They have a long streamlined body, similar to that of the other baleen whales.

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, except for in the Arctic. In summer they feed near the poles, and then migrate to the tropics in the winter to breed. They are rarely seen in Europe, but there have been sightings on ORCA survey trips through the Bay of Biscay by Wildlife Officers and on Sea Safari's, as well as on cruise surveys across to Canada and up to Iceland.

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.

To view this map full screen please click the link 'view larger map' at the top of the map. You can zoom in by using the scroll on your mouse or using the + and - buttons on the map. Click and drag the map to move it around and see different areas. The arrow on the top left of the map will bring out a legend for you. You can 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.