fish colouration

1. COLORATION IN FISHES
PRESENTER: HAMZA SHAMS
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2. INTRODUCTION
• Majority of fishes are vividly and brightly colored.
• It’s one of the most common phenomena found among the fishes.
• Enormous range of colors and patterns that produced in fishes are generally related to
their environment.
• Normally, darker on the dorsal and lighter on sides or ventral side. i.e gives them
protection from above and below.
• have uniform coloration as found in the gold fish etc.
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3. GENERAL DESCRIPTION
• Free swimming; simple coloration, whitish belly, silvery lower sides,
back are blue or green.
• Bottom dwellers; strongly marked above while pale beneath.
• Coral reefs; most brilliantly & elegantly colored, includes Cardinalfishes,
butterflyfishes, triggerfishes, parrotfishes etc.
• Oceanic; silver in the upper; red in the middle range; and violet or
black in the greater depths.
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4. FOUND AT DEPTHS PARROT FISH(CORAL REEFS)
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5. SOURCES OF COLOR
• Due to schemachromes ( physical configuration) & biochromes (true pigments).
• Schemachromes:
• White: skeleton, gas bladder, scales & testes.
• Blue & violets: iris.
• Iridescent: scales, eyes & intestinal membranes.
• Biochromes includes;
• Carotenoids; yellow, red.
• Chromolipoids; yellow to brown.
• Indigoids; red blue & green.
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6. CONTINUED..
• Melanin; black or brown
• Porphyrins & bile pigments; red, yellow, green, blue, brown.
• Flavines; yellow often with greenish fluorescence.
• Purines; white or silvery
• Pterins; white, yellow, red, orange.
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7. PRESENCE OF BIOCHROMES
• Carotenoids and purines appear in fish skin Liver, eggs and eyes have carotenoids.
• Melanin occur in the endoderm & skin.
• Porphyrins found in muscle and blood.
• Bile pigments are found in skeleton and bile.
• Flavines are found in blood, muscle, spleen, gills, heart, kidneys, eggs, liver & eyes.
• Purines are in the scales and eyes also.
• Pterins are in the eyes, blood, liver, kidneys & stomach.
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8. SPECIAL CELLS FOR COLOR / PIGMENTATIONS
• Two kinds of cells; chromatophores & iridocytes.
• Chromatophores; impart true color.
• Located in dermis of skin, either outside or beneath the scales.
• Also found in peritoneum and deeply around the brain and spinal cord.
• Basic chromatophores are;
• Erythrophores; red and orange.
• Xanthophores; yellow.
• Melanophores; black.
• Leucophores; white.
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9. IRIDOCYTES
• Called mirror cell, because they contain reflecting materials that mirror colors outside
the fishes.
• Having purines large crystals that are incapable of movement.
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10. SIGNIFICANCE OF COLORATION
• for communication with either the members of same species (intraspecific) or with
different species (interspecific).
• Intraspecific signals; for recognition, threat or warning.
• For sexual purposes
• Recognition of their parents e.g in Hemichromis which are
bright during period of caring young ones.
• Interspecific signals; For warnings or intimidating potential predators.
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11. RAPID AND SEMI PERMANENT ADJUSTMENT
• Rapid adjustment; is by pigment granules within the chromatophores by expansion and
contraction.
• Semi permanent; by an increase in numbers of chromatophores as like artist increases
the number of stipples for shading.
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12. HORMONAL
CONTROL
• Due to general agreement that coordination of color
change is by interaction of nervous system and
hormonal control.
• In scyllium, darkening as a black background response
involve MDH(Melanin dispersing hormone) & Paling
on a white background involves MAH(melanine
aggregating hormone).
• Also evidences found in someTeleosts ( Anguilla,
Ictalurus, and Fundulus)
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13. FUNCTIONS OF COLORATION (COTT, 1940)
• Principal functions of coloration are;
• Concealment;
• General color resemblance
• Variable color resemblance
• Obliterative shading
• Disruptive coloration
• Disguise
• advertisement
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14. CONCEALMENT;
GENERAL COLOR RESEMBLANCE
• Important in resemblance b/w fish and its background. E.g many coral reefs are very
bright in colors according to colors in that coral reefs.
• Some Fishes living over light shaded bottoms are light colored but over dark bottoms the
same species are dark.
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15. VARIABLE COLOR RESEMBLANCE
• Ability of fish to change color gradually or rapidly to match its background.
• Occurs in life history stages e.g in rainbow trout (stream resident phase) is multicolored
including dark spots(young) and rosy sides in adults.WhileThe same individuals in sea are
blue above and white below.
• Variations also occurs according to seasons, day or night.
• E.g trout occupying bright or partly shaded in summer while in ice covered or extreme winter
they are evenly dark.
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16. OBLITERATIVE SHADING
• Countershading, orThayer's law, is a method of camouflage in which an animal’s
coloration is darker on the upper side and lighter on the underside of the body.
• Surface normally toward light source is counter-shaded by darkening while surface
toward shadow are counterlighted.
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18. DISRUPTIVE COLORATION
• also known as disruptive camouflage or disruptive patterning.
• Surface of fish is covered by irregular patches of contrasted color & tones that draw
attention away from the original shape which they have.
• Prevent or delay as long as possible recognition on sight.
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20. JACKKNIFE FISH ANGEL FISH20

21. DISGUISE
• Simply tends to reduce the resemblance of the fish to itself.
• Deflective and directive marks are important here.
• Deflective marks are those which deflect the attack of an enemy from a more or less
vital part of the body to some other part. E.g dark spot on the tail of the bowfin
• Directive marks divert the attention of prey from the most dangerous part of the
predators’ part. E.g in stargazers feeding habit.
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22. GOOSE OR ANGLER FISH HAVING LUMINOUS BULB
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23. REFLECTIVE MARKS
STARGAZER MONK
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24. DEFLECTIVE MARK (BOWFIN FISH)24

25. ADVERTISEMENT
• Coloration for advertise or reveal.
• E.g in Darters of American streams and also members of the Perch family (Percidae)
are the most brightly.
• Significance for sexual recognition.
• E.g of sticklebacks suggest value of color in sexual recognition.
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26. AMERICAN DARTER26

27. MALE’S BELLY IS RED IN STICKLEBACK
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28. USE IN CLASSIFICATION
• Used often as character to separate taxonomic units .
• Exact pattern of chromatophores are often in genetic control, use in
classification.
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