Changes

Plankton live in both salt and fresh water. Plankton include both plant life (phytoplankton) and animal life (zooplankton). Typical organisms of the zooplankton are about the size of a pinhead. Like dust specks in the air, they can be easily seen by snorkelers or scuba divers when they are crosslit by bright sunlight. Common elements of the plankton include tiny jellyfish and comb jellies, copepods, and dinoflagellates.  

Plankton live in both salt and fresh water. Plankton include both plant life (phytoplankton) and animal life (zooplankton). Typical organisms of the zooplankton are about the size of a pinhead. Like dust specks in the air, they can be easily seen by snorkelers or scuba divers when they are crosslit by bright sunlight. Common elements of the plankton include tiny jellyfish and comb jellies, copepods, and dinoflagellates.  

Although zooplankton drift with the water, they do swim at low speeds and over small distances. In particular, most zooplankton undergo a diurnal ''vertical migration,'' swimming higher in the water during the night and sinking to lower depths. A jocular zoologist once gave a paper the rhyming title "Diurnal migrations of plankton crustaceans."{{citation needed}}

Although zooplankton drift with the water, they do swim at low speeds and over small distances. In particular, most zooplankton undergo a diurnal ''vertical migration,'' swimming higher in the water during the night and sinking to lower depths. (Jocular zoologists once gave a paper the rhyming title "Diurnal migrations of plankton crustaceans.")<!--It was Baylor and Smith, but I can't find a good citation online. Will supply when I find it.--->

Some dinoflagellates are bioluminescent, and create the luminous trails seen behind ships at night in tropical waters. Kipling described the effect in his poem ''The Long Trail:''

Some dinoflagellates are bioluminescent, and create the luminous trails seen behind ships at night in tropical waters. Kipling described the effect in his poem ''The Long Trail:''