Most of the veliger sampling methods discussed require the use of a plankton net with 64 µm mesh; this mesh size is equal to size 25, or 200 meshes per inch. The two most common types of plankton nets are the "Student" net and the Wisconsin net. Both nets are generally used to strain a large volume of water (usually more than 200 L) and reduce it to about 20 ml. The volume of water sampled can be calculated using the formula: volume = r²(h), where r is the radius of the net opening and h is the distance through which the net traveled. When using a pump, volume can be calculated with a timed volume estimate. The inside of the net must be washed from the outside prior to emptying the jar (Student net) or bucket (Wisconsin net). This rinses into the funnel or bucket any organisms that may be clinging to the net mesh.

**Student Net**

**Wisconsin Net**

For information on calculating data retrieved from plankton nets, see Analyzing Plankton Tows, Pumped Samples, and Shallow Water Samples.