Communication Signals

1. Communication Signals • Visual Signals • • Most important communication signal • • Large variety of signals – Different species use different “languages” – Some cues are recognized between species

2. How visual signals are produced • Types of coloring – Pigments - Colored compounds

3. Kinds of Pigments in Fish • Carotenoid pigments – Bright reds & yellow – Green when they overly blue structural color • Melanins– Dark red, brown, black • Purines (guanine) – Colorless crystals responsible for some structural colors

4. Common Color Patterns • Red coloration • Poster colors • Disruptive colors • Countershading• Eye ornamentation • Lateral stripes • Polychromatism

5. Poster Colors • Bright, complex color patterns – Some fish use this to advertise when protecting territories – May serve to signal shoal – In some cases it may be used for predator avoidance •

6. Disruptive Coloration (Camo!) • Disrupt the outline of the fish – Make them less visible – Often associated with beds of plants Also known as “protective resemblance” or “aggressive resemblance”...depends on state of animal.

8. Countershading • Being dark on top, light on bottom – Look like substrate from above – Look like water surface from below

9. Eye Ornamentation • Either to disguise the eye or emphasize it – Disguising the eye • Minimize contrasting color • Field of spots around eye to disguise pupil • Eye lines that match pupil

11. Eye Spots • Usually at base of caudal fin – Usually used to confuse predators • Common in some fry – Sometimes used for species recognition

13. Lateral Stripes • Mid-lateral band usually • Best developed in schooling fish – Keep school oriented while confusing predators – Makes it hard to pick out individuals

15. Polychromatism • Dominant members are often more brightly colored – Makes it easier to attract mates – But, makes them more conspicuous to predators