Board Thread:General Discussion/@comment-26200221-20151211162449/@comment-24152851-20160221225236

Well I'm no shark expert, but it appears flinging their jaw allows them to catch the faster moving fish.

Look, I said rocket launchers do help in survival. But the question is, are they worth it? There needs to be a balance of efficient energy expenditure and the fact that survival is drastically decreased without rocket launchers.

Partially true. It means a feature's larger size and function was selected against, but the feature itself isn't. In an environment where all of the population has equal chance of survival, with limited resources to all, it's those which have more ebergy available who are more survival fit. Vestigial features (when they were still functional) were often too energy costly, with the energy better spent elsewhere like the brain or leg muscles, so they gradually shrunk. But, in some cases a vestigial feature can be selected against if it becomes harmful in a new environment, and will recede even quicker.