BIOLUMINISCENCE IN FISH

MUHAMMED ANZEER F12.05.09

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

It is the production and emission

of light by a living organism.

Widespread across marine

zooplankton and micro-nektonic

life.

BIOLUMINESCENCE(BIOS - LIVING,LUMEN - LIGHT)

MECHANISM Product of a reaction

- Chemical (luciferin)

- Enzyme (luciferase).

Luciferin-indole derivative consisting of

tryptamine,arginine, and isoleusine.

The most common luciferin is Coelenterazine.

Vargula luciferinCoelenterazine

Luciferin + Luciferase Oxyluciferin,

(emitting light).

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.

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.

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.

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.

TYPES OF BIOLUMINISCENCE

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.

photobacterium leiognathi photobacterium phosphoreum

Many species, including Photobacterium

leiognathi and Photobacterium phosphoreum

and , live in symbiosis with marine organisms.

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.

In which the bacterial

organ is situated near the

anus from a gut

diverticulum.

It is enclosed in a black

epithelium exept

anteriorly.

Eg;Opisthoproctus

Opisthoproctus soleatus

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.

Eg;Photoblepharon

They glow

countinuosly,(can only

hide by a shutter or

rotating them into a

black lined pocket).

Photoblepharon

In Chlorophthalmus

the light is very much

dimmer than those of

Photoblepharon.

Chlorophthalmus

PHOTOBLEPHARON

Spectacularly

luminescent fish(10^10

bacteria/cm^3!!!!!!).

Used to search corals

during day time and at

night hunts small

copepods.Flashlight fish

PHOTOPHORES

A number of fish mostly deepsea fish

possess characteristic luminescent organs

namely PHOTOPHORES.

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).

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

through the aperture.Photophores from the dragonfish Malacosteus.

Specialised gland cells of the epidermis.

Show considerable variation in their number and mode of distribution.

PHOTOPHORE WITH INTRINSIC PHOTOCYTES

Ventral series of

photophores

(camouflague).

The lateral

photophores

(signalling).

Eg;Lantern fishLantern fish

TYPES OF PHOTOPHORES1.SERIAL VENTRAL PHOTOPHORESThey are large and ventrally directed in shallower

species.

Eg; Stomias and Chauliodus

StomiasChauliodus

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.

Generally they occur on the lateral and ventral

sides of the body and sometimes in head also.

3.GLANDULAR LUMINOUS TISSUE

These patches emit very rapid high

intensity flashes(10per sec).

Streaks of some glandular

tissue occur (flanks of

Malacostieds).

It also bears a camouflague function(Macropogon).

Macropogon

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

ALTERNATIVE FORMS

One or two suborbital

organs(Opostomias,Micripnus,Scopelus benoitti

and Pachystomias microdon).

Pachystomias microdon

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.

In angler fish:

Looking like something out

of a science fiction movie, the

anglerfish uses a natural lure to

draw its next meal nearer

Large photophores on the elongated first finrays

of pectoral and dorsal fins.

In toad fish porichtheys:

A large

number of

photophores are

present along the

lateral line.

Used to increase the

visibility of lateral

photophores.

Eg;Hatchet fish and

Scopelarchus

A Hatchetfish showing off its glow

YELLOW LENSES

Scopelarchus

Eg; ophisthoproctus and argyropelecus.

Difficult to find these fishes from below.

Cracking of ventral camouflague system using

filtering lenses.

Opisthoproctus Argyropelecus

Used to circumvent the camouflague of

prey.

Possess visual pigments absorbing red

light.

Eg;Malacosteus and Pachystomias

Having large redemitting

photophores underneath the

eye.

RED HEAD LIGHT FISHES

Illuminates the prey with a light of a

wavelength that the prey can’t detect.

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.

Malacosteus

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

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).

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.

THANKS