GENERAL ANATOMY AND FINS
TAIL/ CAUDAL FIN
When seeking to identify marine life, colour may prove to be a poor starting point as colours may change for several reasons (see below). The best starting point is usually gross anatomy/ morphology, including fin shapes, relative fin positions, tail shape and body shape.
A heuristic key to fin layout and some major fish Families is HERE.
Further clues may be garnered from the habitat in which the animal is found, (e.g. sandy bottom, coral reef) and its behavior (e.g. shoaling/ territorial). Further details and terms are to be found on the ABBREVIATIONS page.
Below are some of the anatomical terminologies and points to note.
Environment: Some fish (and cephalopods) have the ability to change colour and/ or markings according to background e.g. Peacock Flounder.
Time/ Activity: Some fish will change colour dependent upon the time of day or activity level e.g. Coney Grouper, Parrotfishes.
Spawning: Some animals will change colour/ intensity during spawing periods e.g. Nassau Grouper.
Mood/ Communication: Some animals will change colour as a signalling mechanism e.g. Reef Squid.
Age: Many fish have juvenile stages markedly different in colouration and/ or pattern compared to adults. e.g. many Damselfishes.
Sex: There maybe marked sexual dimorphism, including protogynous hermaphroditism, with "Initial Phase" and "Terminal Phase" e.g. Wrasses, Parrotfishes.
Races: Some species have one or more distinct races, differing in colouration e.g.Hamlet, Coney
Some Reasons for Colour Variations