A brief account of bio luminescence in fishes

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.