Fat vs Thin tentacles

[Titus07]

I have three RBTAs in my tank but they have different looks. All came from the same animal. One has fat tentacles while the other two have thin ones....on any given day. Aside from location, all seems to be the same for these animals. The fat one gets more light than the other two, could this be the determing factor?

 

[mobert]

It is true in my tank. The ones with more light and flow are fatter and more bubbly.