Light Experiment

On the 7th day the triops are already 3 to 5 mm long. Now we can easily watch them with the naked eye. They still swim very close to the surface. If the heat comes from a light bulb then this heat is one of the reasons that keeps triops near the surface. But there is also another one.

We are going to do a little light experiment. But don't worry. Your triops won't get hurt a bit. Do this experiment in the evening when no sun light is shining through the windows or just close the blinds for a while. Then turn off the aquarium headlight and turn on a light on the right side of the aquarium. This can be your desk lamp or a flash light. Do not put the light source too close to the aquarium because it may generate too much heat.

As soon as you turn the light source on you should notice a migration towards that light. Like a flock of sheep the triops will swim towards the light source. After about 5 minutes most of them should be on the right side of the aquarium. Then place the light source an the opposite side. You should then notice the same migration in the other direction.

We observed that triops swim towards light. But why exactly are they doing this ? The answer is simple, and I am sure you already figured it out. The first reason is that light means warmer temperatures. Since triops need warm water they are much better off to follow the light and stay in those parts of the water which are heated by sun light or in an aquarium by the light bulbs. The other reason lies in their feeding habits. As naupli larvae they are filter feeders and eat unicellular and smaller multicellular organisms that float in the water. Most of those organisms prefer the sunlight themselves. Some of them are autotroph which means they get their energy through photosynthesis. So by just following the sunlight the triops are sure to find the warmer regions of the water and to find plenty of food.