Plankton net

One common method for collecting a plankton sample is to tow the net horizontally using a low-speed boat.

Then the plankton net is then lowered horizontal to the water surface at the side of the slowly moving boat.

John Vaughan Thompson developed a plankton net during his return voyage from Mauritius, which reached the UK in 1816.

Impressed by marine bioluminescence in small crustacea he later named Sapphirina, he felt "under great obligations to this beautiful little animal, which by its splendid appearance in the water induced me to commence the use of a muslin hoop-net, which when it failed to procure me a specimen, brought up such a profusion of other marine animals altogether invisible while in the sea, as to induce a continued use of it on every favourable opportunity."

Darwin describes this "contrivance" as "a bag four feet deep, made of bunting, & attached to [a] semicircular bow this by lines is kept upright, & dragged behind the vessel".