1) Fish possess various adaptive structures like electric organs, poison glands, and sound producing organs. This document focuses on bioluminescence organs. 2) Bioluminescence involves the production of light by living organisms through a chemical reaction between luciferin and luciferase enzymes. It is common in marine life. 3) Fish bioluminescence can involve symbiotic bacteria or intrinsic photophores. Photophores are light-emitting organs that vary in structure and function between fish species.

1. MUHAMMED ANZEER F
12.05.09

2. INTRODUCTION
Fish posses a number of adaptive structures
which have been evolved to meet special
requirements faced by them.
Most important of them are:
 Electric organs
 Phosphorescent organs
 Poison glands &
 Sound producing organs

3. BIOLUMINESCENCE
(BIOS - LIVING,LUMEN - LIGHT)
 It is the production and emission
of light by a living organism.
 Widespread across marine
zooplankton and micro-nektonic
life.

4. MECHANISM
 Product of a reaction
- Chemical (luciferin)
- Enzyme (luciferase).
Luciferin-indole derivative consisting of
tryptamine,arginine, and isoleusine.

5.  The most common luciferin is Coelenterazine.
Coelenterazine Vargula luciferin

6. Luciferin + Luciferase Oxyluciferin,
(emitting light).

7. BIOLUMINESCENCE IN FISH
 “One of the most important processes in the
ocean, and yet hardly anyone was studying it.”
 These are absent in freshwater forms.
 These mostly the characteristic feature of
midwater and bottom dwelling deep sea fishes.

8.  Fishes with luminiscent organs are world wide
in distribution.
 Majority of them are bathy pelagic living at a
medium depth(500-2000).
 In fishes the luminescence is generally blue or
green.

9.  70% of all species collected from Bermuda
and south atlantic had light organs.
 Systematic survey shows 10-15% of all marine
fish genera contain luminous organs.

10. TYPES OF BIOLUMINISCENCE
1.Results from the presence of luminous bacteria
living on the fish in a symbiotic manner.
2.Arises from the self luminous cells on the
fish,the photophores.

11. BACTERIAL PHOTOPHORES
Photobacterium is a genus of gram negative
bacteria in the family vibrionaceae. Members of
the genus are bioluminiscent that is they have the
ability to emitlight.

12. Many species, including Photobacterium
leiognathi and Photobacterium phosphoreum
and , live in symbiosis with marine organisms.
photobacterium leiognathi photobacterium phosphoreum

13. STRUTURE AND MECHANISM OF
BACTERIAL PHOTOPHORES
 These are associated with diverticulum of the
gut( infect during the larval life).
 Surrounded dorsally and laterally by a connective
tissue reflecting layer.so light emerges
downwards and is refracted by translucent
ventral muscles before passing out of the ventral
region.

14. Eg;Opisthoproctus
 In which the bacterial
organ is situated near the
anus from a gut
diverticulum.
 It is enclosed in a black
epithelium exept Opisthoproctus soleatus
anteriorly.

15.  Where it shines into a long ventral hyaline light
guide surrounded dorsally by reflecting
platelets.
 The boom of the fish being completely flat light
emerges evenly over the whole of this
flattened sole.
 used for ventral camouflague.

16.  They glow
countinuosly,(can only
hide by a shutter or
rotating them into a
black lined pocket).
Eg;Photoblepharon
Photoblepharon

17.  In Chlorophthalmus
the light is very much
dimmer than those of
Photoblepharon.
Chlorophthalmus

18. PHOTOBLEPHARON
 Spectacularly
luminescent fish(10^10
bacteria/cm^3!!!!!!).
 Used to search corals
during day time and at
night hunts small
Flashlight fish
copepods.

19. PHOTOPHORES
A number of fish mostly deepsea fish
possess characteristic luminescent organs
namely PHOTOPHORES.

20. STRUCTURE OF PHOTOPHORE
 Similar to eyes
 Having a reflecting layer and capped with a lens.
 Richly innervated and certainly under nervous
control.
 The transmitter commonly is adrenaline or nor
adrenaline(in hatchet fishes it is epinephrine).

21. In the two mages,
 ‘c’ is the light-emitting core
 ‘r’ is the reflector surrounding
it and
 ‘f’ is a filter to give the emitted
light
The light bounces around
until It exists the photophore
Photophores from the
through the aperture. dragonfish Malacosteus.

22.  Specialised
gland cells of
the epidermis.
 Show
considerable
variation in
their number
and mode of
distribution.

23. PHOTOPHORE WITH INTRINSIC PHOTOCYTES
 Ventral series of
photophores
(camouflague).
 The lateral
photophores
(signalling).
Lantern fish
Eg;Lantern fish

24. TYPES OF PHOTOPHORES
1.SERIAL VENTRAL PHOTOPHORES
 They are large and ventrally directed in shallower
species.
Eg; Stomias and Chauliodus
Chauliodus Stomias

25. 2.SIMPLE PHOTOPHORES
 In many genera,there are a red fluorescentviolet
pigment like that of serial types but they usually lack
reflectors.
 Very similar to the unpigmented glandulartissue.

26. 3.GLANDULAR
LUMINOUS TISSUE
 Generally they occur on the lateral and ventral
sides of the body and sometimes in head also.
 These patches emit very rapid high
intensity flashes(10per sec).

27.  Streaks of some glandular
tissue occur (flanks of
Malacostieds).
 It also bears a
camouflague
function(Macropogon). Macropogon

28.  Arranged as one or two rows extending on
the sides from head to tail(scopelus and
halosauropsis).
 Rarely arranged in transverse bands on the
body(Opostomias).
The ObeseDragonfish,
Opostomias micripnus.
Photophores, or light producing
organs, cover the fish in rows
and below both eyes

29. ALTERNATIVE FORMS
 One or two suborbital
organs(Opostomias,Micripnus,Scopelus benoitti
and Pachystomias microdon).
Pachystomias microdon

30.  In deeper
species,the organ is
reduced in size
becomes almost
rudimentary(Malacost
eids). Malacosteids
 In all families these have a red flourscnt
violet pigment in the aperture.
 Stimulated by adrenaline injection.

31. In angler fish:
Large photophores on the elongated first finrays
of pectoral and dorsal fins.
Looking like something out
of a science fiction movie, the
anglerfish uses a natural lure to
draw its next meal nearer

32. In toad fish porichtheys:
 A large
number of
photophores are
present along the
lateral line.

33. YELLOW LENSES
 Used to increase the
visibility of lateral
photophores.
A Hatchetfish showing off its glow
Eg;Hatchet fish and
Scopelarchus
Scopelarchus

34.  Cracking of ventral camouflague system using
filtering lenses.
Eg; ophisthoproctus and argyropelecus.
 Difficult to find these fishes from below.
Opisthoproctus Argyropelecus

35. RED HEAD LIGHT FISHES
 Used to circumvent the camouflague of
prey.
 Possess visual pigments absorbing red
light.
Eg;Malacosteus and Pachystomias
 Having large redemitting
photophores underneath the
eye.

36.  Retina absorbs around 575nm so they can perceive
redlight(most deep sea fishes - 450-490nm).
 Red reflecting tapetum and increased pigment
density to make up the inevitable loss of sensitivity.
 Illuminates the prey with a light of a
wavelength that the prey can’t detect.

37. Malacosteus

38.  Can observe common
red and brown animals
of the middle
depth(which can’t be
illuminated with the
more common blue
emitting photophores).
Eg;Diaphus Diaphus

39. FUNCTIONS
1.Search the prey in the dark
waters.Eg:Anomalops.
2.Attract prey near the mouth.
3.Some times acts as defensive organ.
4.Warning signal for the predatory animal.
5.Recognising individuals of the same
species(schooling).

42. CONCLUSION
 New species of luminescent fish are discovered
yearly
 But the function and physiology of the light organs
remain more speculation than scientific fact.
 Access difficulties, expensive ship and submarine
cost ,and low funding have hamstrung effect and
our knowledge of bioluminescent fish lags behind.