Polychaetes should be preserved as soon as possible after collecting, which is especially important in warm weather. Material for morphological examination should be fixed in 7% formalin made up with sea water and after 5-7 days should be rinsed in freshwater and stored in 70% alcohol. When the material is to be used for molecular studies, it has to be fixed in 95% alcohol which needs to be changed after 24 hrs. Such material should ideally be kept in the dark and in the fridge. Freezing of fresh samples is not recommended as it is difficult to preserve the material as it defrosts rapidly. Ideally, material for both morphological and molecular should be collected.
Ideally worms in muddy tubes should be removed but these must be retained and kept with the specimen before preservation of the animal. In contrast worms in calcareous tubes should be fixed in situ as the tubes have useful morphological characters. Careful labeling is critical, important to use waterproof paper which is alcohol and ink proof and labels should be inserted inside the vials with well-sealing lids to prevent evaporation of the alcohol. Well preserved animals are much easier to work with than poorly preserved ones. Complete animals are needed in many cases for accurate identification, fragments may be impossible to identify.
A good quality dissecting microscope and a compound microscope plus light sources are essential together with a dissecting kit. Photographs of fresh material may be useful. Colour patterns of live material may be diagnostic in some species. Animals should be examined under the dissecting microscope in petri dishes being completely covered with 70% alcohol. Staining with methyl green dissolved in alcohol can highlight soft structures which can facilitate identification. At no stage should the specimens be allowed to dry out because dried or dehydrated worms are very difficult to identify. To examine chaetae preparation of slides and access to a compound microscope, glass slides, cover slips and glycerine are needed. For preparation of permanent slides the glycerine needs to be replaced with aqamount. More specific methodological recommendations are given for individual families. The characters which are important to distinguish species depend on the particular family and these are illustrated for each species.