Humpback whales feeding at Wilsons Prom

Humpback whales are rorquals, a type of baleen whale (Mysticetes) that feed by expanding their throats to engulf and filter huge quantities of water, catching plankton, krill and fish. The baleen plates are large and bristled and hang down in the hundreds from the roof of their mouth, acting like a sieve as the tongue pushes the water out through the fine bristles. 

Although baleen is also called whalebone, it is in fact made up of keratin, a substance similar to that is found in our hair, skin and nails! Baleen is hard and durable like bone, but also has some flexibility. In the past, it was used in many every-day items including children’s toy, buggy parts, umbrella ribs and corsets.

At least three broad feeding styles can be found within the baleen whales: gulp feeders, skim feeders and bottom feeders. Gulp feeders, like humpback and minke whales, engulf a large mouthful of food and water, close the mouth part way and, with the tongue, force the water back out through the baleen. The food cannot pass through the baleen and is swallowed whole. Long, parallel grooves, or pleats, run the length of the throat, allowing the throat to distend – almost like the pouch of a pelican. This feeding style works well with schools of small fish or large plankton.

Skim feeders, like right whales, pass through patches of plankton-rich water with their mouths open. As food and water flow into the mouth, the water passes out through the baleen. Food items, trapped against the fringe of the baleen can be directed to the throat by the tongue.

While the southern Humpback whales and Right Whales mainly feed in the nutrient rich waters of the Southern Ocean, whales have been sighted to feed on fish off the Wilsons Promontory islands on their southerly migration, as in this picture taken near Cliffy Island.