Plankton

Plankton ( altgr. πλαγκτόν " The Wandering " ) is the name for organisms that live in the water and their swimming direction is dictated by the water currents. Organisms that can swim against against currents are called nekton.

As the founder of systematic plankton research of marine biologist Johannes Peter Müller may apply, which began on the island of Helgoland from 1846 to the scientific study of those organisms; he called the plankton then lift. Of great importance is also the Kiel oceanographer Victor Hensen, in 1889 the first scientific expedition headed that dealt only with plankton.

Habitats

Plankton is almost ubiquitous in the aquatic environment. However, most marine areas are considered as ecological deserts due to the low abundance of nutrients. If, in standing inland waters and rivers to excess nutrients, the strongly growing phytoplankton to the so-called can cause " upset ".

Freshwater plankton is called Limnoplankton, sea water plankton as Haliplankton.

Size differences

Plankton come in all sorts of shapes and sizes. If the individual organisms smaller than 4 micrometers ( microns ), one speaks of picoplankton. In this plankton are mainly Picozoa ( only type Picomonas judraskeda ), which can account for up to 50 percent of the biomass in the nutrient-poor areas of cold coastal seas. Picozoa are so small that they are barely visible in the light microscope.

Other particularly small organisms (4-40 microns ) are the nanoplankton (also nannoplankton ) attributed. The smallest forms are bacteria, all of which have up to two million in a teaspoon of water space. The plant representatives, phytoplankton, are usually smaller than the diameter of a human hair (about 0.1 mm).

The names of picoplankton and nanoplankton are not related to dimensions in picometers and nanometers. For example, individuals of the nanoplankton are 4000-40000 nanometers in size.

When zooplankton, there are also tiny forms. However, up to 9 meters wide jellyfish that can not swim against currents, including definition of the plankton because they are drifted by the flow. For species that ( the Nekton ) do not belong to the active floating organisms, the medium-sized species than Mesoplankton, the big macro as plankton and the giant forms, such as the already mentioned species of jellyfish, plankton as Mega or Megaloplankton be called.

We distinguish:

• Bacterioplankton ( bacterial plankton): about cocci and rods (Bacillus, Escherichia, Vibrio )
• Phytoplankton ( plant plankton ): diatoms ( Bacillariophyta ), green algae ( Chlorophyceae ), dinoflagellates ( dinoflagellates ), etc.
• Zooplankton ( animal plankton ): various protozoa ( Acantharia, foraminifera ), rotifers, arrow worms, larvae and some adult (adult ) specimens of bristle worms, fish larvae, many crustaceans and their larvae (including krill ), some insect larvae, Stachelhäuterlarven (Starfish among others), mussel larvae, tunicates ( Tunicata ) and their larvae, etc.

Zooplankton

All planktonic organisms engaged in photosynthesis, but feed on other organisms, will be counted for zooplankton. A distinction is made between herbivorous and carnivorous species: for herbivorous zooplankton include those species that feed directly on phytoplankton, zooplankton, which feeds on other zooplankton, is called a carnivore. These feeding relationships are coupled together through the food web.

Zooplankton plays an important role as a food source for fish and many other marine life. Without the plankton of the Arctic waters lacked the huge plankton filtering baleen whales such as the blue whale or fin whale the food source. Copepods of the genus Calanus, together with the krill huge amounts of animal biomass in the plankton. Often large areas of sea color just by the presence of plankton below the water surface and thereby give the fishermen references to schools of fish that feed on zooplankton, such as herring and mackerel.

Phytoplankton

Single-celled diatoms make up the bulk of phytoplankton. The cells are of a two -part shell ( theca ) surrounded silica. Various studies show that the largest amount bound is not bonded to carbon in tropical forests, but in the plant plankton of the oceans.

Tychoplankton

Tychoplankton consists of organisms that only occasionally in the plankton.

Plankton filter feeders

Plankton is the base of the marine and freshwater food webs. The species listed below are some of the best known representatives of this diet:

• Blue whale
• Razorback
• Whale Shark
• Basking shark
• Flamingo
• Atlantic herring
• Sardine
• Mussel

Plankton -like plastic parts

In the seas driving waste flow, weathering and other influences were broken up into smaller and smaller pieces in the last few decades. These particles have partially in size, appearance and swimming behavior similarities with plankton and mingle with this, so that they are mitgefressen of plankton filter feeders and can produce harmful effects. This phenomenon is sometimes referred to as " plastic plankton ".