Conservation and Collecting

Don't collect unnecessarily, always bear conservation in mind. However nudibranchs only live for one year or less; they lay thousands or tens of thousands of eggs at one time and their populations fluctuate wildly. If you are in a poorly known part of the world aim to preserve six specimens of each species. (Only the British Isles and California class as well known).

Collecting nudibranchs

  1. Bringing up your finds. The easiest container to use whilst diving is a strong plastic bag. Some people prefer smaller bags or plastic tubes. If you use tubes, fill them with seawater so that you will be able to open them when they are under pressure.
  2. Photography. Underwater photographs of the animals in position on the rocks or food are very useful as they may give clues as to what the species was eating. Use a macro lens or extension tubes and a flashgun. Remember that a white animal will tend to over-expose so stop down if necessary. Photograph spawn coils as they may belong to the animals.
  3. Surface photography. Photograph the animals in a shallow dish or a narrow tank. Flash light is best, but must be aimed from the side or at 45 to the front glass or water surface. A black background is best for most species; this can be rendered out of focus and unlit by placing it well away from the back of the tank or bottom of the dish (see diagrams). Two small flashguns give the best results. Use a small aperture (f16 or f22) and move the flash closer or further away to alter the exposure. Trial and error may be needed to get the right exposure; increasing the magnification will mean increasing the light by moving the flash(es) closer. Try f16 with the flash(es) at 9" (23cm), 12" (30cm) and 16" (40cm), at 1:1 magnification with ASA 64 film, and experiment from there.
  4. If you are diving regularly you can always take the animals back into the water on a shallow dive and photograph them with a Nikonos and extension tubes.
  5. Recording your animals. Examine the animal with a x10 lens or stereomicroscope if it is small. If you cannot identify the animal positively from a book then make a sketch and notes on its colour. A rough diagram with notes and arrows to indicate colour pattern is sufficient. Note surface consistency and any spicular structures in Dorids, and make detailed drawings of one ceras or rhinophore if these have complicated colouring which cannot be shown in the sketch. Note the date, depth and place of collection, and give the animal and notes a number so that you can relate the two after preservation. The same number can be put onto the photographs. Write a label for the preserved animal with the same details in indian ink on good writing paper, and put it into the bottle of preservative.
  6. Don't forget to collect and preserve a small piece of the animal's food as well, as this will provide useful information on diets. Sponges, bryozoans and hydroids can be put straight into 70% Alcohol, but most other organisms preserve better after relaxation in MgCl2 solution.