Whales and Dolphins
Our attitudes towards whales have undergone a massive change in the past few decades. Growing worldwide concern for these gentle marine creatures has fuelled the transition from a commercial exploitation that severely depleted the global population of large whales to an almost universal ban on whaling. Today, a rapidly growing tourist industry provides people with the opportunity to see these remarkable animals in their own environment, while instances of mass strandings bring great public support in efforts to return the animals to the sea. (See whale strandings - how you can help.)
Cetaceans are divided into two groups - the baleen whales and the toothed whales. The toothed whales, as their name suggests, use teeth for feeding, possess only one blowhole opening and have asymmetrical skulls. Baleen whales use baleen (a rigid, keratin-like material similar to our fingernails) which hangs in vertical strips from the upper jaw. Baleen acts like sieves to filter out the tiny crustaceans (krill) on which they feed. Large whales, such as the humpback, can consume over two tonnes of krill each day.
A number of feeding strategies are used to maximise the intake of krill. A remarkable example is the 'bubble-netting' behaviour of the humpback whale, in which the animal expels a stream of bubbles from the blowhole while slowly ascending in a spiral to the surface. The bubbles form a cylindrical wall which surrounds the krill and traps them. The whale then swims upwards through the cylinder with its mouth open, consuming the concentration of krill.
Most species of toothed whale are able to use echo location to form what is effectively a mental picture of their surroundings. These whales produce pulses of very high frequency sound which strike objects and return as echoes. From these echoes, the animal is able to gain detailed information on the size, shape, distance, and even texture of the objects around them. It is believed that the spectacular behaviour known as breaching also serves as a means of communication. Whales such as the humpback often smack the surface of the water with their tail to warn of danger.
Southern right whales travel north from June to September to the waters of southern mainland Australia and return southward between September and late October. A proportion of the population gives birth in Tasmanian waters. Most sightings occur on the east coast. Although this may be simply a consequence of the higher population of human observers in the east, it is likely that the humpback and southern right whales prefer the calmer waters of the east coast.
The stranding record provides an indication of the species that occur in Tasmanian waters. Some species have been recorded only once and have never actually been observed live in Tasmanian waters.
Further information on why whales strand, and what you can do to help, can be found on this website. The following table presents the Tasmanian stranding record to the end of 2009.
Contact: Threatened Species & Marine SectionKris Carlyon
Wildlife Biologist (Marine)
134 Macquarie Street HOBART TAS 7000
Phone: 03 6165 4324
Fax: 03 6233 3477
There are numerous websites with further information on whales. These include:
International Whaling Commission - www.iwcoffice.org/
Cetacean Society International Home Page - http://csiwhalesalive.org
Pacific Whale Foundation - www.pacificwhale.org/about/index.html
Evans, P. G. H. (1987). The Natural History of Whales and Dolphins. Facts on File Publications, New York.
Tucker, M. (1989). Whales and Whale Watching in Australia. Australian National Parks and Wildlife Service.
Tasmania Online | Service Tasmania
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