The effects of light and food consumption on the deflation on Diodon holocanthus

Diodon holocanthus have a unique defense mechanism against predation. The balloonfish are able to inflate their bodies with water and air if necessary, enlarging themselves and protruding their spines. The purpose of this study is to see how food consumption and light affect the rate of deflation, or returning to their normal state from inflation. The study was conducted using 20 balloonfish over a six day period. Two tanks were used to house the subjects, which were each split into halves for a total of four sections, representing a different environment. Each tank was separated into fed and non-fed sides, in which one whole tank represented a light environment, and the other a dark environment. The fed subjects were given a limitless supply of food while the non-fed sections were starved. A net was used to apply consistent disturbance in order to stimulate maximum inflation in the balloonfish. Time measurements were taken every twelve hours at 11:00AM and 11:00PM. The experiment consisted of 149 total trials of which 27 trials led to no inflation. The results for the study showed that the fed balloonfish deflated at a faster rate than the non-fed subjects. Furthermore, on average, the balloonfish that were placed in the dark environment would deflate at a faster rate than the subjects in the light environment. It was also observed that balloonfish in the wild would deflate at a slower rate than those in captivity. Further implications may explain that Diodon holocanthus would be able to best protect itself using this predatory defense mechanism when starved and in a light environment.

Aron and Oded