1. 1. Distribution of light in the ocean Sunlight zone
Biozone
Euphotic
Epipelagic
Disphotic
Mesopelagic
Bathypelagic
Aphotic
Abyssopelagic
Fig 13.9

2. 2. Adaptations to the deep sea
Hatchet fish
2. Adaptations to the deep sea
Bioluminescence
Mating
Feeding
Gulper eel
Female angler fish
Fig 15-14

3. Bioluminescence

4. A. Bioluminescence a) What? b) Where? Marine bacteria Dinoflagellates
Definition: The emission of ecologically functional light by living organisms
Light is produced by a chemical reaction within the organism – no ‘input’ of energy
Note: phosphorescence – emission of light with input of energy
fluorescence – input of energy to excite a molecule giving off light
b) Where?
Marine bacteria
Dinoflagellates
All major phyla

5. c) How bioluminescence works
Photon of light
“optimizer”
enzyme
substrate
Core of the reaction
has strong antioxidative properties
detoxifies tissues by taking up oxygen free radicals
usually brought into the system by diet or synthesis internally
d) Likely originated to detoxify oxygen derivatives

6. Bioluminescence in different organisms

7. e) Examples of bioluminescent organisms & their molecules:
Coelenterazine: most ‘popular’ of the luciferins (substrate); known in cnidarians, molluscs, chaetognaths, fish.
Can act alone or with another enzyme
Often acts together with aequorin
Chemistry: Imidazolopyrazinone
Found in all tissues of the animal
Highest concentration in digestive gland, liver hepatopancreas, organs with high levels of oxidative reactions

8. Aequorin: a ‘luciferase’ (enzyme) that requires calcium
Aequorin is called a ‘photoprotein’ because it requires calcium to work with a luciferin (such as coelenterazine)
Apoaequorin
Colenteramide
And CO2
photon
Ca 2+
Apoaequorin
(enzyme)
Coelenterazine
(substrate) O2
Aequorin-
Coelenterazine
(excitable
intermediate)
Bacterial luciferin: most often harnessed by other animals and used for light emission (e.g. fish, squid)
Vibrio: a marine bacterium (free-living) that is an endosymbiont in squid
Luminescence is dependent on cell density
(reduced riboflavin phosphate FMNH2 )

9. Aequoria victoria

10. f) When is bioluminescence used?
(1) lure
Angler Fish

11. (2) Burglar Alarm: startling predators of your predator
Cephalopod predation is facilitated by dinoflagellate luminescence
‘Seizure’
Pre-attack
‘Positioning’
Ghost shrimp
squid
(Fleisher and Case: Biol. Bull : )

12. (3) Alarm/warning of other colonies: e.g. Pyrosomes
Stops feeding and swimming current

13. More examples: Krill – use bioluminescence for attracting mates
Bacterial endosymbiont in the squid Euprymna scolopes
E. scolopes burries in the sand during the day and forages at night.
Uses the bioluminescence produced by the Vibrio to counter-shade it against the moonlight so that prey won’t see its shadow.
Hatchling squid pick up the bacteria and develop a special pouch for them

14. B. Adaptations - Mating
Parasitic male

15. C. Adaptations - feeding
Chauliodus sloani
Large teeth
Hinged jaw
Chiasmodon niger
Vast stomach!
Fig 15-15

16. Chauliodus sloani
Gulper eel

17. Carnivorous tunicate
Atrial siphon
Oral siphon
(mouth)

18. Carnivorous sponge: Asbestopluma
From Barkley Sound

19. Amphipod
crustacean

20. Asbesopluma hypogea –
Carnivorous sponge from the Mediterranean (Marseille, France)