THE OTHER SIDE OF THE WORLD

HUMPBACK WHALES

NAME
• comes from the distinctive hump in front of their small dorsal fin

LUNCH
• often feed in large groups
• humpbacks are baleen whales, which means they filter their food through baleen plates
• they strain krill, anchovies, cod, sardines, mackerel, capelin, and other schooling fish from the waters
• some humpbacks have been observed creating "bubble nets" to catch their prey
• the whales dive deep then swim up in a spiral pattern, while releasing a steady stream of bubbles from their blow holes
• as the bubbles rise they form a "net" that surrounds the whales' prey
• the whales swim up through the centre of the bubble net and feed on the prey trapped inside

COLOUR
• mainly black or grey with white undersides to their flukes, flippers and bellies

SIZE
• 15m long

NOTICEABLE CHARACTERISTICS
• their long flippers & famous foe their singing ability
• Humpback whales are extremely active, often slapping their flippers and flukes on the surface of the sea
• they also breach more than any other baleen whales
• male humpbacks produce a long series of calls that are normally heard during the winter breeding season, although songs have been recorded in the summer
• the whales may repeat the same song for several hours

HUMPBACK SONGS
• appear to be shared by all singing members in the same area of the ocean
• as the song changes, all members sing the new song
• the same song is sung in spite of the great distance between groups in the population (up to 5000km)
• this sharing of songs may occur when groups intermingle during migration or in shared summer feeding grounds

"Researchers are not certain why humpback whales sing. They have hypothesised that the songs attract females or are used as territorial markers"

HABITAT & ECOLOGY
• humpback whales make extensive seasonal migrations between high latitude summer feeding grounds and low latitude wintering grounds
• winters are spent mating and calving in warm sub-tropical waters, with an annual migration back to colder waters to feed

BREEDING
• humpback whales have complicated courtship behaviours
• often, many males will surround a single female hitting each other in a competition to get close to her
• females become pregnant about every two to four years, and are pregnant with each calf for about 11 to 12 months
• the calves can grow 0.5 metres per month while nursing on their mother"s rich milk
• females nurse their newborn calves in warm, shallow water
• because of an absence of teeth (which can be used to estimate age in other mammals), it is difficult to tell the age of a humpback whale but they are believed to live to 80

pictures & text from googleRead more