How Being Small Helps Fish Survive
A new study, by researchers at James Cook University, has also found that bigger fish use the threat of punishment to keep competitors in line.
For instance, among goby fish only the largest two individuals, a male and female, have mating rights within a group. All other group members are non-breeding females, each being consistently 5-10 percent smaller than its next largest rival.
The reason for the size difference was easy to see, explained Marian Wong, who led the study. “Once a subordinate fish grows to within 5-10 per cent of the size of its larger rival, it provokes a fight which usually ends in the smaller goby being expelled from the group – and the safety of the coral it occupies. More often than not, the evicted fish is then gobbled up by a predator.”
To avoid being expelled from the group, the smaller fish keep themselves small in order to avoid provoking the big fish. Whether they do so because of stress caused by the bullying of larger fish or voluntarily – by restraining how much they ate – was not clear. [Via]
