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Kai Marns-Morris, wrote on July 28, 2017:

Humpback Whales; by Kai

Humpback Whales

Humpbacks are probably the most well known whales. Humpbacks are huge, amazing, baleen whales known for their active behaviour including breaches. They are filter feeders and are recovering from near extinction.

Identity

These enormous creatures average from 11-16 meters long (the females are generally 2 meters bigger than the males) and weigh about 25-33 ton. The newborn baby whales are 4-5 m and 1-2 ton! With their big back flippers, humpback whales can move themselves at a maximum of 10 knots while awake and 3 knots while asleep. They have a small dorsal fin, an enormous mouth, 2 blowholes on top of the head and 2 long pectoral fins. Their flukes are the biggest of all the cetaceans. The markings on humpback’s tails are unique to that whale. Their body is black with white underside.

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Predators

Humpback whales’ main predators are humans. Their numbers were reduced by over 20 000 (90% of their population) in the time before the whaling ban (in 1986) but are now steadily increasing. Orcas also have been known to prey on juveniles which is why many humpbacks bear scars.

Behaviour

Some interesting behaviours of the humpback whale are:

· Breaching; when a whale launches most of its body straight out of the water before slapping back down on its side. Whales probably breach for their own enjoyment or to communicate to each other with the large slap as they come down (this sound travels very far under water) but experts don’t really know.

· Tail slapping; when a whale sticks its tail out of the water and continuously slaps it. Like breaching, we don’t really know why they do this but one theory is that it is to warn other whales off.

When whales breath, they surface and blow air out of their blowhole before sucking some back in. Whales are known to be able to stay underwater without breathing for 3—45 minutes. When humpbacks are about to dive deep they lift their tails out of the water to get a better angle to dive. Humpback whales can be found by themselves or with a group of up to 15 in breeding or feeding areas.

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Above; This is an image we took with a Gopro.

 

Migration

Every year all the humpback whales move to colder climates and back. In the summer of each hemisphere they move; down to Antarctica in the southern hemisphere and up to Alaska in the northern hemisphere. In winter the whales swim to warmer climates closer to the equator like Tonga. This journey from cold to hot and back is around 6 000 nm and takes them 1 month of non stop swimming. They become very hot in this swim so once they arrive in the tropics they have to continue swimming around slower and slower to cool off and adjust to the temperature change. When they leave the polar regions they don’t all leave at the same time. They follow a particular order: mothers and their calves, immature and mature whales and then pregnant females. When leaving the tropics they go: pregnant females, immature and mature whales then mothers and their calves (backwards).

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Above; Picture taken by our drone in the South Pacific, July 2017

 migration

Above right; Shows the migration routes of whales and the summer and winter feeding and breeding grounds. sighted at; www.whales.org.au/discover/hump/humpm.html

Diet

Although they are bigger than most sea creatures, humpback whales eat only small fish and krill. These fish include: juvenile salmon, herring, mackerel and capelin. Because they are baleen whales they eat by filtering prey from the water with baleen plates. They mainly feed in the polar regions but will occasionally eat when they are in the tropics.

Reaching the size of 10 people and the weight of 400, humpbacks are the third biggest baleen whale. These mammals are very active and we are still learning about their behaviours.

References

· Carwardine, M. (1995)“whales, dolphins and porpoises” . Dorling Kindersly Limeted: London pg’s 76, 18.

· http://www.doc.govt.nz/nature/native-animals/marine-mammals/whales/humpback-whales/

· https://en.wikipedia.org/wiki/Humpback_whale

· http://www.nationalgeographic.com/animals/mammals/h/humpback-whale/

· http://www.nmfs.noaa.gov/pr/species/mammals/whales/humpback-whale.html

· https://www.livescience.com/58464-humpback-whale-facts.html

· http://indopacificimages.com/tonga/complete-guide-to-the-humpback-whales-of-tonga/the-tongan-humpback-whale-migration/

· http://www.doc.govt.nz/Documents/conservation/native-animals/marine-mammals/whales-in-the-south-pacific.pdf

All URL’s sighted on 30/07/2017

cover image taken with our drone July 2017

This entry was posted in Kai's blog, Kids blogs.

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