We now have to discuss gear, but first we must know what we want our gear to do. For our purposes as microbiologists, there are two main kinds of gear that we shall use. The earlier people, who studied phytoplankton, used fine-mesh nets which they towed behind ships at slow speeds. These nets consisted of a metal ring towed by a ‘bridle’ of 3 ropes which came together at a ring that was attached to the main wire. To the ring was lashed a conical net consisting of a canvas top and a silk mesh net proper, usually with 200 meshes to the inch. At the apex of the cone was a ‘bucket’, a glass or metal container in which the organisms were supposed to be finally caught. Similar nets, but with coarser mesh or a graded series of meshes, are still used for animals, (Fig.1) but it is generally believed that nets are useless for the smaller plants. There are two reasons for this: first, the mesh of phytoplankton nets is so fine that it is almost waterproof, in fact I have used this netting to strain water from petrol. It therefore pushes most of the water in front of it and strains only a very small proportion. The second reason is that many of the smaller microbes can pass through the meshes, fine though they are, and so are neither caught nor recognized as part of the flora. Nets come in all shapes and sizes, and each user has his own reasons for the kind of net he employs. Some nets have an inverted cone in front of the net proper, and others are cylindrical with a small cone at the lower end, and there are high-speed nets which are usually encased in some sort of metal or plastic container.
KeywordsMetal Ring Tampa Region Inverted Cone Board Ship Main Wire
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- 2.Wimpenny R.S. 1966. The Plankton of the Sea. Chapter XI: Faber & Faber, London, 1966.Google Scholar