Coral Reef Fish Notes

Coral Reef Fish

Different Fish on the Reef.
Photo by Katja Hasselkus [public domain]

-      Colors, patterns, and morphology (shape) 

o  Morphology

§ Disks and ovals

§ Silvery

§ Sloping head/tapered body

§ Heavy body/large lips

§ Reddish/big eyes

§ Eels

§ Sharks and rays – cartilaginous fish, rest mostly boney fish 

§ Odd-shaped bottom dwellers 

§ Odd-shaped swimmers 

§ Swim with pectoral fins/ obvious scales

§ Small, elongated bottom dwellers 

Diagram of a fishes anatomy.
By Diagram by User:Gdr based on a
drawing by Dr Tony Ayling.
CC BY-SA 3.0

o  Fish anatomy:       
§ Dorsal fin

§ Fin spines

§ Caudal fin (tail fin) 

§ Anal fin

§ Ventral fin

§ Pectoral fin 

o  Patterns: 

§ Line marking radiating from eye

§ Bar (vertical line) 

§ Ocellated spot

§ Stripe (horizontal line)

§ Spot

§ Speckles (fine spots)

§ Band (diagonal lines)

§ Blotch poorly define)

§ Lines (thin markings in any direction) 

o  Specialized cells for color and iridescence:

Chromatophores of a squid. By Minette [CC BY 2.0]

§ Chromatophores: COLOR

·     cells that contain pigments 

·     stimulated by nerve impulses and or hormones·     higher density of cells -> more brilliant color 

§ iridophores:

·     cells with crystals that reflect light 

·     GAUNINE nucleotide 

·     Act like a mirror

·     Typical of silvery fishes

·     Can display different shades of green, blue, pink, and iridescence 

§ Loligo opalescens: (squid) chromatophore where the pigments are spread out, can be stimulated to condensed and can control

§ Hog fish: changes colors, the changes that occur are sometimes so fast that they cannot be tied to a physiological phenomenon. Their skin is actually light sensitive.

§ Color can tell you what stage of life the fish is in or distinguish male from females 

o  Camouflage: for predators and prey 

§ Some fish use camouflage as a foraging strategy: sit and wait hunting

§ Some use it to blend into their surroundings to not get eaten

o  Courtship, mating, egg guarding:

§ Some female fish may be attracted to male fish that change colors

§ Sergeant majors take on darker color when nest guarding

§ Clown wrasses turn bright when spawning 

o  Counter-shading: (ie sharks)

§ Some species use counter-shading to conceal movements

§ Dark on top

§ Light on bottom 

o  Other functions of color and patterning:

§ Conceal eye (false eye on body)

§ Exaggerated size

§ Advertise toxicity

§ Bright colors and behavior 

-      32,000 different species of fish – 40-45% freshwater species