Subject: Infected with parasites. The sausage-like small orange objects on this nudibranch’s gills (Goniobranchus coi) are the egg sacs of a female copepod. Copepods are little parasitic crustaceans that feed on the skin tissue or blood of their host. The morphology (shape) of the mouth of these tiny animals depends on the food source (tissue- or blood-feeders).
Technique: It is usually not a good idea to film the back of an animal, unless… the subject is situated on the back of that animal.