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Light production Thanks to Rebekah Wilkins, Jackie O’Riley.

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Presentation on theme: "Light production Thanks to Rebekah Wilkins, Jackie O’Riley."— Presentation transcript:

1 Light production Thanks to Rebekah Wilkins, Jackie O’Riley

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3 Perciformes

4 LophiiformesPerciformes

5 Light production in fishes Who? scattered among 13 orders, 45 families (Bond Table 19-1) mostly in teleosts, 2 families of elasmobranches

6 Where? mostly deep sea, 300-1,000m up to 2/3 of deep oceanic fishes produce light species of mesopelagic fishes

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9 How? General principle: production of light by ‘cold’ chemical reaction: luciferase Luciferin + O 2 + ATP  oxyluciferin + light

10 How? 1. produce luciferin – usually under neural control may have lens or iris to control emission of light 2. rob luciferin from diet concentrate it in specialized areas of body 3. contain symbiotic bacteria in special structures probably derived from diet occlude with tissue or pigment to ‘flash’ light

11 Why? 1. Predation – reduces prey-seeking energy and time lures on anglerfishes on inside of mouth ( Sternoptyx, Psueodscopelus ) mimic lures of dragonfishes may mimic prey conspecifics cookie cutter shark may appear smaller, less threatening Anglerfish Dragonfish Sternoptyx

12 Why? 1. Predation – reduces prey-seeking energy and time lures on anglerfishes on inside of mouth ( Sternoptyx, Psueodscopelus ) mimic lures of dragonfishes may mimic prey conspecifics cookie cutter shark may appear smaller, less threatening Anglerfish Dragonfish Sternoptyx Lophiiformes Lophiiformes Stomiiformes

13 Why? 1. Predation – reduces prey-seeking energy and time lures on anglerfishes on inside of mouth ( Sternoptyx, Psueodscopelus ) mimic lures of dragonfishes may mimic prey conspecifics cookie cutter shark may appear smaller, less threatening 2. Predation – see prey better ‘flashlights’ under eyes, or in mouth red light of black dragonfish, not visible to prey

14 Why? 3. Defense countershading on ventral surface (hatchefishes) Stomiiformes

15 Counter illumination

16 Why? 3. Defense countershading on ventral surface (hatchefishes) intimidation – appear larger (elongate dragonfish) confuse or startle predator – flashlight fish apparently change position with each flash Beryciformes

17 Why? 3. Defense countershading on ventral surface (hatchefishes) intimidation – appear larger (elongate dragonfish) confuse or startle predator – flashlight fish apparently change position with each flash 4. Communication aggregate conspecifics (flashlight fish)

18 Why? 5. Sexual selection? Melanostomias male is brighter – female may select by brightness

19 Control: lens or iris-like structures control light emission tissue or pigment occlusion allows ‘flashing’ cover the photophore with a membrane or rotate it inward

20 Shining Tubeshoulder Photophores on underside Tube on each shoulder Squirts bioluminescent ink at predators


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