Fisiokimia Sains Hayat

AQU 3013
Fish Physiology System: Sensory System
Dr Siti Ariza Aripin
 Legends about fish before earthquakes
(Daigo, 1985):
 Big catfish stir deep underground.
 Fish rise to the surface of the water.
 Fishing catches decrease near the coast.
 Deep-sea fish float to the surface.
 Goldfish or minnows burrow into the sand at the bottom of their aquaria.
 Carp and goldfish jump out of the water.
 Big shoals of sardines swim up-river.
 Dizzy octopuses float up to the surface.
 Colonies of sea crabs walk onshore.

 Modern reports of pre-earthquake behavior:

 Fish in ponds and tanks oriented themselves in the same direction.
 Physical

STIMULATION Touch

Movement

Light Chemical Sound

 FISH SENSORY
MECHANORECEPTION
Hearing, orientation, lateral line detection

VISION

CHEMORECEPTION
ELECTRORECEPTION Smell and taste
 FISH SENSORY
 Generally fish floats in water

 There are exposed to different kinds of stimulants such as vibration and sound

 They need a system to ensure equilibrium and perceive sound in water

 The mechanoreception system in fish consists of numerous subsystems.

 These subsystems serve to increase the awareness of a fish to its surrounding

environment.

 This helps to increase success in both foraging (feeding) and predator detection and
avoidance.
 FISH SENSORY

Neuromast system on the head

and body

Otolith

Mauthner Neuron

Swimbladder
Lateral Line system
 EYES
 All vertebrate eyes are structurally similar
 (1 pair and located at the head)

 The principle differences in fish eyes relate again to the medium

 Cornea (lens) functions as a single focusing element

 A fish lens is spherical and is not changed for accommodation. Instead the lens is
moved closer or further from the retina
 EYES
 Fish do not have necks, nor can they turn their head to look in
different directions.

 The eye has a wide field of view to make up for this limitation

 The eyeball is elongate, paralleling the long axis of the fish

 The retina extends around the inside of the eye but the greatest
density of receptors is in the posterior field

 Spectacle – transparent layer covered the cornea to protect eyes from

particles, debris. Fish with spectacle – benthic or shallow water
 EYES

 The eye accommodates in the forward field by moving the lens forward or
backward

 The lateral field remains roughly in distant focus.

 Proper placement of such an eye will permit 360 degree vision, in fact a highly
predated fish like Gambusia may have binocular vision to both front and rear.
EYES
 EYES
 Contain fibres that directed to the optic nerve

 Ganglia cells

 Polar cells

 Photoreceptor cells consist of cone and rod cells

 Retina cells or epithelium contain melanin and boundary with coroid layer

 Image definition is based on the reaction of photoreceptor cells consist of 2 main

components : Rods and Cones
EYES

 Rods :
 Image definition of lightness and darkness

 Cones :
 Definition in terms of resolution and colour
 INNER EAR
 The nature of sound transmission in water influence the evolution of
hearing in fish

 Water : Efficient conductor than air

 Sound carries much farther and travels 4.8 times faster underwater than
in air.

 Fish perceive sound by having inner ear

 Function of inner ear:

 Receive sound
 Generate equilibrium and balance
INNER EAR
 INNER EAR
 Most fish tissues are similar in density to water and thus transparent to sound
waves.

 Certain structures (bones or swimbladders) are very different and thus are
forced to vibrate.

 Vibration of sound is detected by otoliths.

 Most fish have irregularly-shaped otoliths. Presumably the projections help

extend the range of detectable frequencies.

Otoliths
 INNER EAR
 Some fish couple the swimbladder to the inner ear, permitting
amplification of very fine vibrations and sensitivity to a wide range of
frequencies:
Cypriniformes
 Superorder :
 Ostariophysi (Siluriformes, Cypriniformes, Gymnotiformes)
 Clupeomorpha (Clupeiformes)
Mormyriformes
 Osteoglossomorpha (Mormyriformes)

Siluriformes Clupeiformes
 INNER EAR
 Fish have ears located internally near the brain.

 It consist of membranous labyrinth composed of sacs, and canals that are

filled with liquid

 Consist of 2 main parts :

 Pars Superior (Dorsal)
 Pars Inferior (Ventral)
INNER EAR
Pars superior

Pars inferior

Abbreviations: A, H, P - anterior, horizontal, posterior

semicircular canals; AN - auditory nerve to saccule; CC -
crus commune; L - lagena; LM - lagenar macula; LN -
eighth nerve to lagena; LO - lagenar otolith; S - saccule;
SM - saccular macula; SO - saccular otolith; U - utricle;
UO - utricular otolith.

http://www.life.umd.edu/biology/popperlab/background/anatomy.htm
 INNER EAR
 Pars Superior (Dorsal)

 Function in equilibrium system and gravity detector

 3 semicircular canal
 Horizontal Canal
 Anterior Canal
 Posterior Canal

 Sac-like structure : Utriculus with presence of otolith

 Ampullae (fluid sensing chambers).

 INNER EAR
 Pars Inferior (Ventral)

 Function in sound detection

 Consist of 2 sac-like structure

 Sacculus
 Lagena

 Both structures contain otolith and function in sound reception

 INNER EAR
Equilibrium System and Gravitational Detector
 Majority fishes have 3 semicircular canals
 Anterior Canal
 Posterior Canal
 Horizontal Canal

 The three fluid-filled semicircular canals are oriented at right angles to one
another so as to detect momentum changes about any axis.

 Each canal has an ampulla containing a sensory hair cell area and each gelatinous
cupula attached to the hair cell cilia
 INNER EAR
Equilibrium System and Gravitational Detector
 A nerve ending (Cupula) extends into each canal. Any angular movement
of the fish would induce relative motion in the fluid, bending the cupula
and stimulating the nerve.

 Changes of pattern of nervous impulses from the sensory hair cells to the
balance equilibrium center in the medulla provoke the appropriate motor
responses by the fish such as movements to maintain a stable visual field
and fin movements to restore body equilibrium.
INNER EAR

Otolith

Lateral Line system

 INNER EAR
OTOLITH
 Otolith, calcium structure in innner ear

 Located in the inner ear

 Otoliths are suspended in fluid and are surrounded by ciliary bundles

 Differential amplitude and phase motion of otolith in each chamber cause

bending of cilia mechanically stimulating neural transmission to the auditory
centre of the brain.

 This enable fish to have a sense of hearing

 INNER EAR
Sound Reception
 All 3 sac-like structures (utriculus, sacculus and lagena) have large areas
of sensory epithelium called maculae

 Near the maculae, there is a gelatinous membrane, cupula thickened by

mineral deposition forming the Otolith
INNER EAR

Each sac-like structure has its own

otolith

Otolith of Utriculus : Lapillus

Otolith of Sacculus : Sagitta

Otolith of Lagena : Astericus

Figure 1. Inner Ear of Fishes, Lateral View. SC=

Semicircular Canals, U= Utriculus, UO=Utricular Otolith
or Lapillus, M=Macula, SU=Sulcus, S=Sacculus,
SO=Saccular Otolith or Sagitta, L=Lagena, LO=Lagenar
Otolith or Asteriscus. Modified from Popper and Coombs
(1982).
 INNER EAR
Sound Reception

 Sagitta is the major receptors of sound in fish

 Fish hear when sound waves cause the sensory epithelium and sagittta to
vibrate

 Vibration of Sagitta resulted in bending of sensory cells and transferred

into a sound signal by auditory nerves
 LATERAL LINE

 The lateral line system consists of bendable nerve endings in a series of

mucous-filled canals.

 The lateral line system is a collection of small mechanoreceptive

patches or neuromasts located superficially on the skin or just under
the skin in fluid-filled canals on the head and body of all fishes.
 LATERAL LINE

 The mechanoreceptive component of the neuromast is the hair

cell - the same sensory cell found in all vertebrate ears,
including the human ear.

 Neuromast transduce mechanical energy into electrical energy

when their hairs or "cilia" are displaced.
Figure 4. Macula within the utriculus (otolith
chamber) (Bouins, H&E, Bar = 36.4 µm). 1. ciliated
sensory cells; 2. sustenticular cells; 3. connective
tissue; 4. cupula (gelatinous matrix); 5. globular
sensory epithelium; 6. collagenous connective
tissue; 7. otolith chamber; 8. cranium.
LATERAL LINE
LATERAL LINE
LATERAL LINE
 LATERAL LINE
What Can The lateral line system do ?
 Enable detection of both vibrations in the water and changes in the pressure field
set up as the fish swims.

 Provides information to the fish about movements of nearby organisms, very-low-

frequency sound, differential current velocity, and back pressure built up as the
fish approaches an obstacle.

 The lateral line sense is sufficiently directional to enable blinded fish to find and
capture prey.
 LATERAL LINE

 Lateral line not only exist along the body but throughout the head region
 LATERAL LINE

 Vibrations in the water or differential pressure in different parts of the canal

cause the fluid to move and distort the nerve endings.

 The nerves contacting these receptors enter the brain in close association with the
auditory processing areas of the fish nervous system.

Vibration
 NOSTRIL

 The simplest is a forward-directed flap that divides the nostril into incurrent and
excurrent openings and deflects water into it when the fish is moving relative to
the water.

 Some fish have cilia that create a continuous current through a U-tube nostril.

 Others have a relatively thin membrane separating the nostril and the buccal
cavity so that pressure changes in the buccal cavity associated with breathing
create an aspiratory effect to draw water in and force it back out.
 TASTE SENSORY

 Taste buds in fish are not confined to the tongue or buccal cavity.

 They may be distributed over the entire body surface, but are usually
concentrated on lips, barbels, head and elongated feeler-type fin rays in fish
having those structures.

 Touching the barbel with a glass rod elicits no response. But touching it with a
food item will provoke an immediate snap.
 ELECTRIC ORGAN

 The ability of certain fishes to detect electric fields ranks among the biological
wonders of the world.

Stunning and Avoiding intruders

obtaining prey or predators

Identifying and locating nearby object

Electrolocation
 ELECTRIC ORGAN

 Electric organ consists of special cell: electrocytes that exist in the muscle tissue
cell

 Electrical discharges are under neural and hormonal control

ELECTRIC ORGAN
ELECTRIC ORGAN

Passive Electrosensitivity

TYPE OF
ELECTROSENSITIVITY

Active Electrosensitivity
 ELECTRIC ORGAN
Passive Electrosensitivity
 Ability to detect and respond to electrical impulses generated by muscle
contraction in other organisms.

 Found in all sharks, rays, sturgeons, paddlefish, lungfish and a variety of teleosts.

 Some can detect fields as low as 1 mV/km. This is roughly equivalent to one
flashlight cell 1500 km away. They can detect small electric fields from
respiratory or heart muscles of prey.
 ELECTRIC ORGAN
Active Electrosensitivity
 An electrically active fish produces an electric field around itself.

 Action of muscles produces an electrical discharge (modify muscle units into

batteries.)

 Distortions in that field provide information about the environment.

 The result is a discharge of a pulse of direct current. With enough cells in the
battery, large potentials can be created (up to 500 volts in the electric eel). Such
potentials can stun prey or would-be predators.
 ELECTRIC ORGAN

 The electric eel (Electrophorus electricus) is a snake like fish which is found
mostly in the Amazon Basin in South America.

 It lives in marshy areas, especially in places where the dissolved oxygen in water is
low.

 Electric eels have the capability to fatally electrocute a horse.

 ELECTRIC ORGAN

 The vital organs in the electric eel are located immediately behind the head.

 The remaining 7/8 of its body is the tail which is the electricity generating organ.

 This organ is composed of 5000-6000 elements, arranged like a dry battery.

 The head acts as the +ve pole of the battery while the tail acts as the -ve pole.
When the eel is at rest there is no generation of electricity.
Thank you