Over 80,000 species in total with fossils back to the Cambrian period. The moon phases also impact on some species. Than when there is a full moon. Such urges are apparent even on heavily clouded nights, when a partial or full moon contribute a minimal amount of light. It is unknown, whether it is the darkness which affects the eels or whether it is related to gravitational pull.
More active sperm are generally more likely to succeed in fertilising an egg.
One of the most commonly used fish anaesthetics . Chemical name tricaine methanesulphonate. Administered as a bath . Excreted by goblet cells. Mucus Slimy excretion produced by specialised goblet cells .