Plankton, Plankton and more Plankton!
Plankton is one of the most important group of organisms in the ocean because it is the number one produce (in terms of numbers.) This and the fact that a large portion of plankton are plant-like (phytoplankton) and the rest are consumers of only plankton, makes plankton the base of the food chain. plankton is made up of the larval formes of many organisms, diatoms, dinoflagellates, gelatinous zoo plankton, and other organisms that so not have the swimming capability to swim against the current. Oddly though, plankton is only found in the photic zone (the area where there is enough light for photosynthesis to take place.) The depth of the photic zone may very depending on the clarity of the water.
Some of the larva found in the plankton do not spend their entire life living in the plankton, this type of plankton is called meroplankton. For example as larval stage of fish cannot swim against the water currents but the adult fish can. Diatoms are unicellular phytoplankton which have cell walls that are made of silica. Dinoflagellates are also unicellular organisms, but dinoflagellates are also able to ingest food particles as well as use chlorophyll for photosynthesis. Dinoflagellates have cell walls that are made out of cellulose.
Gelatinous zooplankton (also known as blue water plankton, because it is most abundant off shore in deep clear water,) which includes jellyfish, is the newest major category of plankton. Prior to 1974 gelatinous zooplankton was considered to be a relatively small and hard to sample contributor to the marine economy, so it was never studied in depth. In 1974 William Hamner used scuba gear to personally go into the water to observe and collect the organisms there. He found that gelatinous zooplankton was as abundant as crustaceans.
Crustaceans previously were thought to be the most abundant because the samples that oceanographers were able to collect contained animals with hard exoskeletons and unidentifiable goo. This goo was the remains of many animals, but the animals had been destroyed beyond recognition. This occurred because the oceanographers collected their samples via a net with a very small mesh size (between 200 micrometers and 20 micrometers. This discovery of lots more plankton increased the intricacy of the food web at the very basic level.