Fins increase the Tiranhas mobility Fins increase the Tiranhas mobility in the water allowing it to hunt more efficientlyin the water allowing it to hunt more efficiently when legs are no longer useful

A Tiranha's gills allow it to breathe in water, making it possible to stay in the water longer. Staying in the water allows the Tiranha more time to hunt animals in the water as well escape land dangers.

Adaptations

Gills (anatomical)

Fins (anatomical)