Fishing co-operatively and singing long complex songs which change over time.
Humpbacks are Baleen Whales, which means that they have sieve-like structures in their mouth instead of teeth, but unlike the Right Whales they have ‘pleated throats’, making them ‘Rorquals’ along with other filter-feeders such as the Blue Whale. Unlike other rorquals Humpbacks feed primarily on fish (most of the others prefer plankton). They should not be confused with Humpback Dolphins which are Toothed Whales.
Humpback Fishing Techniques
Sometimes Humpbacks fish alone and simply gulp down shoals of fish, at other times they may use their enormous flippers to frighten or stun the fish, and occasionally they will use ‘bubble-netting’. If a single whale is using this technique he will dive beneath the shoal and then swim around it while blowing plate-sized bubbles. He starts directly under the fish and then gradually surfaces, widening the surface as he comes up. The shoal is now pushed to the surface of the water, trapped in a ‘net’ of bubbles, and the whale simply ploughs through them with his mouth open.
Communication and Co-operative Fishing
Incredibly Humpbacks will often work together when bubble-netting a large shoal of fish. A number of whales get together and make a huge ring of bubbles, then they each swim up through the centre of their ‘net’ and leap into the air with a mouthful of fish. This work requires a lot of complex co-ordination, and, while nobody is sure how the whales achieve this, it is probably done by sound (although some people have gone so far as to suggest that whales might be telepathic!).
Humpback Song
Different groups of Humpbacks sing different songs, and in any one place these songs will change over the breeding season. Next year the songs will be different again, but phrases will be remembered from last year and incorporated into the new serenade. Each individual male Humpback hangs head-down in the water and sings his unique song, but no one is quite sure what it means (listen to a song). In fact nobody seems to understand exactly how the sounds are made – no air leaves the mouth.
Migration
There are about 70,000 Humpbacks worldwide and all migrate over long distances (up to 16,000 miles). You can watch this year’s migration of the Pacific Humpback Whales courtesy of the BBC. Although whaling took a heavy toll in the past the world population now seems to be recovering.
When do Humpbacks Sleep?
No whales really sleep. If they did they would drown! Instead they have evolved a fascinating solution where the two halves of their brain are poorly connected, so that one half can sleep while the other remains alert, listening out for danger and remembering when it is time to surface again and breathe.
Main reference: Collins Wild Guide – ‘Whales and Dolphins’ by Mark Carwardine, 2006.
Other articles by John Blatchford
