Blue Whale

Blue Whale – Balaenoptera musculus

Size: 24 - 30 m
Key feature: Giant size and tall blow
Behaviour: Raising its large tail flukes as it dives

Appearance

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 which a human could swim through! They have the tallest blow of all the whales, reaching 10 m 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, but larger ones are too heavy. When they dive they often raise their wide tail flukes above the surface. Although they are the biggest animal, they feed on Krill which are like small shrimp. They need to eat 4 tonnes or more each day, 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 to the Bay of Biscay for those lucky enough to be on the right trip.

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, they don’t reach maturity until they are 7 years old and have one calf every 2 – 3 years.