From the smallest to the largest creatures of the planet earth – in the sea live numerous organisms, which feed on a very special and often forgotten by humans food source: the plankton. But what exactly is behind this term?
Plankton – more than the “wandering around”
Whether microscopic organisms or organisms up to nine millimeters in size – the life forms that are combined under the term “plankton” may at first glance be inconspicuous. But they play an important role in the food pyramid. The term plankton comes from ancient Greek and means translated as much as the “stray”. This designation is based on the observation that the small organisms swim in the water with the stream and thus act as if they wander aimlessly.
The plankton can be divided into several subgroups. Thus, a distinction is made between the nanoplankton, the zooplankton – which is of animal origin and includes, for example, larvae, worms or crustaceans -, the phytoplankton – which is of plant origin – the bacterioplankton, the mesoplankton, the macroplankton and the megaloplankton according to the organism size. Phytoplankton plays a crucial role in the food chain. It is used to feed the zooplankton, which in turn is the main food for some whale species.
The little ones as food for the greatest
The zooplankton, also known as krill, reaches a size of up to six centimeters. So it is very small, if you imagine that it serves as a food source of the largest mammals on earth. Krill filters the phytoplankton, has blue luminous organs and usually occurs in small swarms. When such flocks drift around in the sea, the numerous microorganisms attract many whales up close.
The approximately 80 species of whales worldwide can be divided into two groups: the baleen whales and the toothed whales. Only the first group uses plankton as an exclusive nutritional basis. The baleen whales, which include, for example, the blue whale or the fin whale, filter the plankton out of the seawater through their comb-like horn plates, the whitetails. They absorb the seawater through their huge mouth and press it through the so-called beards so that the plankton remains in the mouth and can be digested further.