Whales are among the largest living beings that have ever lived on Earth. It is especially astonishing that some of these enormous animals feed almost exclusively on very small organisms. This is made possible by special physical adaptations and an efficient way of feeding.
In general, whales are divided into two subgroups: toothed whales and baleen whales. Toothed whales have teeth and actively hunt larger prey such as fish or squid. Baleen whales, on the other hand, have no teeth. These include, among others, the blue whale and the humpback whale. These whale species feed mainly on krill and plankton.
Instead of teeth, baleen whales have so-called baleen plates in their upper jaw. These are several hundred horny plates, often several meters long, that hang closely side by side. Between the individual baleen plates there are small gaps of about one to three centimeters. Together they form a kind of filter or sieve.
To feed, baleen whales open their mouths wide and take in large amounts of seawater. This water contains plankton, especially zooplankton such as krill. The whales then close their mouths and press the water back out with the help of their tongues. The plankton remains caught on the baleen plates. The accumulated food is then swallowed.
The term plankton refers to all organisms that cannot move by their own power but drift with ocean currents. A distinction is made between phytoplankton, plant plankton, and zooplankton, animal plankton. Zooplankton often feeds on phytoplankton and forms an important food base for many marine animals, including baleen whales.
Although plankton is very small, it occurs in enormous quantities in the ocean. Krill in particular often appears in large swarms. A single large whale can eat several tons of krill per day. Thanks to this enormous amount of food, whales meet their energy needs and can become full despite the small size of their prey.
In summary, baleen whales are perfectly adapted to life as plankton feeders thanks to their baleen plates and their special filtering technique. This unique feeding strategy enables them to feed successfully on tiny organisms and still be among the largest animals in the world.
Rosamaria Kubny, PolarJournal