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Frogs are mostly nocturnal but some of the species also shows diurnal characteristic.

Our optimum light cycle (adult) is 14 hours light : 10 hours dark.

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For my eggs and embryo, It will be better if it is far away from UV light sources as they are very sensitive and high chance of getting mutation if exposed to these sources.

It applies to tadpole also, they do not need much light and some of it even suggest to keep them in constant dark due to:

Had most rapid growth in constant dark.

Reduced mortality.

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b. Hey! don't forget I like to bask too.

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b. Hey! don't forget I like to bask too.

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Naturally frog tend to bask a lot under the sun.

The reason behind this is for them to obtain enough UV from the sun to produce vitamin D for their bone development.

Thus, the facilities should also have lamp that can mimic the natural sunlight to give UV.

One of the commercial bulbs are modified Eiko® M16 halogen bulbs (Eiko® Supreme) that can produce the light with UV that produce 5 to 20 fold increase in the conversion of vitamin D3.

Things to be consider:

1. Lights should be placed a sufficient distance from animals so as not to cause burns or other problems, but close enough for the ultraviolet to be effective.

2. The light can be highly influence to the reproduction of the frog, thus, the general light cycle should be strictly followed.

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a. Turn the light off if you want to see me!

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a. Turn the light off if you want to see me!

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Axolotl is a nocturnal animal (active at night)

The preferable light cycle is 12 hours light : 12 hours dark.

They do no have a good eyesight, but at the same time their eyes are very sensitive to the light.

Thus, you normally only can see the axolotl emerge out when the light is out or when the light is dimmer.

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Axolotl favour low light intensity or no light at all.

Since it is impossible in a laboratory setting as the researcher need light for their vision, thus plants should be added as a place for the axolotl to hide.

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Axolotl will stressed out if they exposed to high light intensity for a long period of time.

There are a few sign to know if the axolotl is stressed out:

Gills will be curl forward.

Curled tail.

Low appetite.

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Zebrafish is a diurnal animal (active during the day).

The light cycle is the opposite of what the rodents need which is 14 hours light and 10 hours dark.

Zebrafish are easily to be startled, so we are not advisable to turn off or on the light suddenly, instead a gradual brightening/dimming period of around 20-30 minutes is recommended.

The optimum light intensity that can be tolerated by zebrafish is quite wide which are around 54-324 lux.

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b. How unsuitable lightning impact zebrafish?

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b. How unsuitable lightning impact zebrafish?

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i. Impact on eye condition
Light intensity does not causes serious damage to the zebrafish eyes, this is because they are able to recover their eyes from the abnormal exposure once they have return to a housing with normal light and dark cycle.

ii. Constant exposure to the light
Constant light exposure can limit the fish not to lay the eggs.

iii. Constant darkness
Constant darkness will halt or delays the general development of embryos.

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c. It is not just about the problem in zebrafish

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c. It is not just about the problem in zebrafish

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Another things to be consider about is the fish tanks it self.

High light intensity may promote the growth of the algae inside of the tank, which is not desirable and may affect the hygiene of the tank.

If we allow the algae to grow, this can also promote the growth of bacteria at the same time which may cause bacterial infection to the zebrafish at the same time.

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I am neither a nocturnal or diurnal animal, but I am a crepuscular animal where I am the most active during the dawn and dusk period.

The ratio of light and dark cycle is 12hours Light : 12hours Dark or 14hours light : 10hours dark cycle.

The amount of light that is suitable for me is 200 Lux at one metre above the floor.

As rabbit is crepuscular, thus it is advisable for the lab to prepare the dawn-dusk transition lightning that can mimic the natural transition.

It is advisable that the duration of the transition should be within 30 minutes to 2 hours. This can be done by changing the dimness of the light gradually before the complete darkness or light.

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b. Expose me with light for longer time and the correct light colours, I will give you more baby (Leverets)!

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b. Expose me with light for longer time and the correct light colours, I will give you more baby (Leverets)!

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bi. Amount of light period

Naturally, rabbits are more sexually active during the summer and spring where the photoperiod are longer.

Thus, we in the lab can also mimic this condition to improve the rabbit reproduction.

From a research by Mousa-Balabel & Mohamed, when the rabbit treated with a longer photoperiod of 14 to 16 hours of light together with the presence of melatonin, it can increase the semen volume, concentration,  percentage of live spermatozoa and mass motility in a buck.

While for doe, it can improve the  sexual receptivity and fertility.

bii. Light colour

It has been found out that when compared to rabbit under white vs red light and white vs blue light, the litter size and litter weight are greater under the red and blue light compare to the white light.

Not only that, the pre-weaning mortality are also lower in blue and red light.

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c. Becareful! I don't need a very high light intensity.

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c. Becareful! I don't need a very high light intensity.

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Light intensity of 800 - 1100 lux are potentially harmful to the rabbit, especially the albino one like New Zealand rabbit.

Thus, if house them in this amount of light can causes retinal damage to the rabbit.

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Rotating cage position (vertically) as the rodents live on the top receive highest amount of light compare to the bottom, thus to reduce the stress faced by them, it is more proper to rotate the cage.

Use a gradual light transition instead of putting out or turn on the light suddenly which mimic the natural light changes. This has been suggested that the rodents will have better social behaviour.

If mice are observed during the dark phase red or sodium lamps should be used to minimise any disruption to their nocturnal activities.

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Since, now we know rodents are nocturnal, so what happen if we let them stay in constant dark environment?

It was found out that the rodents have circardian clock of 24.2 hours. Thus, if we let them stay at constant night they will keep active for a longer period of time compare to the normal 12 Light: 12 Dark.

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a. Before we talk about the lighting of the room, let's understand about the rodents' eyes first!

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a. Before we talk about the lighting of the room, let's understand about the rodents' eyes first!

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Rat, mice and hamster are nocturnal animal (active at night).

They have dichromatic color vision due to the presence of only 2 types of cones.

One of the cone has its maximal photopic sensitivity at a wavelength of 510 nm (the green cones)

Another has its maximal photopic sensitivity at a wavelength of 360 nm (blue - UV cones)

Thus, they can distinguish between green and blue, but for red they perceive it as dark.

The dark color also can be explained as rats have 1% cones (compared to human 5%) and only 99% rods (which distinguish the dimness of the light).

This concludes that they are far more sensitive to the brightness instead of the color. As an implication, the control of the brightness in the rodents breeding area is very important to ensure they are at its maximal physiological potential and to perform normal activities.

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The light preference of a rat depend on few factors; like type of rat

Albino rat and mice, very sensitive to the light as they lack the pigmentation in their eyes.

They prefer light intensity as low as 25 lux. If the intensity > 60 Lux, it can cause them to become blind.

As for the pigmented rat, they can accept light of higher intensity of 60 lux.

Despite of that, in order for a worker to work with a good performance, intensity of 210 lux is recommended.

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Thus, the recommended level is, room illumination levels of 323 lux measured 0.91 m from the floor, with the maximum rack row-level light of 32-40 lux using a prototype room with wire-mesh-fronted stainless steel caging.

The light and dark cycle is 12 hours light and 12 hours dark (12L:12D) or 14 hours light and 10 hours dark (14L:10D).

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This is how 60 Lux looks like. Image retrieved from: https://www.bike24.com/p2365464.html

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I know the above statement is quite contradict and I am sure you wouldn't want to in such an area where you need to squint your eyes every time you want to read the label or write something right?

Thus to optimise the condition for both rat and the workers it is advisable to:

Insert a small shelter for the rat to hide for the rat to control the light exposure themselves. The small shelter preferably to be red as they see red as dark.

Use an opaque caging.

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c. Lighting is not one size fit all, it depends on other factors too!

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c. Lighting is not one size fit all, it depends on other factors too!

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i. Rat age
Juvenile rats (age <30 days) is more resistant toward higher light intensity compare to the elderly rats.

ii. Gender
Female (Doe) are more vulnerable to higher light intensity compared to the male rat (Buck).

iii. Light exposure history of the animal
Rat reared in a light intensity (400 lx) has less susceptible damage to higher light intensity compare to the rat that reared in a low light intensity (6 lx).

The exact amount of difference on the different factors are not mention.

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di. Do you know you can 'stress out' the rat just by giving them wrong 'amount' of light?

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di. Do you know you can 'stress out' the rat just by giving them wrong 'amount' of light?

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i. Circadian dependent retinal light damage

It occurs if we expose the rat with high light intensity during the night and violate the 12L:12D ratio.

Only a short period of this exposure is enough to induce the loss of photoreceptor cells.

ii. Rat's behavioural change

High light intensity causes the loss of the normal behaviour (i.e. boxing/wrestling and chasing)

Without these behaviour the rat seems like losing their socialise ability.

iii. Change in the duration of oestrus cycle with the change of L:D ratio.

iv. Constant light exposure induce stress.

This is because the rat will have increase in corticosterone levels if keep expose to the light.

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Dii. Adverse effect if we did not give the correct amount of light to mouse.

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Dii. Adverse effect if we did not give the correct amount of light to mouse.

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The high light intensity causes the behavioural change in the dam. The dam do not care much on their pup and build inadequate nest that causes the pups being scattered throughout the cage.

Not only that they did not tae care of the pup properly, but they also have very low reproductive efficiency.

In addition, when high light intensity given to BALB/cJ mice there are increase in both wall-leaving and cage-crossing behaviours.

Phototoxic retinopathy can also occur if mice are exposed to very high intensity of the light.

Exposed them to continuous light for a week had increased urine corticosterone:creatinine ratios which indicates they are in stress.

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diii. Hamster can be aggressive if you didn't give them the correct amount of light!

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diii. Hamster can be aggressive if you didn't give them the correct amount of light!

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In a short day condition (shorter light exposure time) the hamster tend to be more aggresive than they are in a long day.