Transcript Light production

Light production
Thanks to
Rebekah Wilkins, Jackie O’Riley
Perciformes
Perciformes
Lophiiformes
Light production in fishes
Who?
scattered among 13 orders, 45 families (Bond Table 19-1)
mostly in teleosts, 2 families of elasmobranches
Where?
mostly deep sea, 300-1,000m
up to 2/3 of deep oceanic fishes produce light
600-700 species of mesopelagic fishes
How?
General principle: production of light by ‘cold’ chemical reaction:
luciferase
Luciferin + O2 + ATP  oxyluciferin + light
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
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
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
Lophiiformes
Dragonfish
Lophiiformes
Sternoptyx
Stomiiformes
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
Why?
3. Defense
countershading on ventral surface (hatchefishes)
Stomiiformes
Counter illumination
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
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)
Why?
5. Sexual selection?
Melanostomias male is brighter – female may select by brightness
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
Shining Tubeshoulder
•Photophores on
underside
•Tube on each
shoulder
• Squirts
bioluminescent ink at
predators