MR.HK

sensory receptor:

• pineal gland
• lateral line
• eyes
• chemical sensory
• otolith

- function

*collect light

*focus image to the retina

*transform image to the neural signals

-how to reduce lighting???

*pupillary operculum expands/ contract to adjust the amount of the light

*nictitating membranes cover up to reduce too much light.

-how to adjust low/high light??

*low. 

^cones contract

^rods closer to light and not shield by melanin

*high

^opposite occurs

^cones closer to light

^rods extended n shield by melanin

-how to focusing on images???

*made by changing lens shape

*made by changing distance between retina and lens

2. pineal gland

-component???

*pinealocytes (photoreceptor cells)

*ganglian cells (second order neurons)

*glial cells (supporting cells)

-function

*detect light

*produce melatonin

-blind cave fish

*larvae detect the light and show a shadow response

3. chemical sensory

-types

*olfaction - smell

*gustation - taste

-OLFACTION

*nare?? 

^small opening near the mouth

^inside the nare are bilateral structure with numerous epithellia cells called lamellae

^number of lamellae depends on age and size of fish

GUSTATION

* based in taste buds

* cover entire body

*exposure of heavy metal quickly destroy taste buds but can recover when placed back in pristine water

*barbel is the modified structure for gustation

4. lateral line

*mechanorecemtive organ

*function

-detect vibration

-detect changes in pressure

-helps predator locate prey

-helps prey avoid predator

5. otolith 

*located just behind the brain

*why have otolith???

-more dense than water

-move more slowly than the fish body

*function

-sensitive to gravity 

-sensitive to acceleration

-aids in fish balance

*important of otolith

-determine the natural diet of predators

-determine places where fish live

-assist in determining fish age (darkslow n lightfast)

hahahahahahaha korang belaja la jugak malam ni k... :)