The Tiger shark and the green sea turtle
Tiger sharks (Galeocerdo cuvier) hunt green sea turtles using several key adaptations.
The sharks use electrical current detection and finely tuned senses to track their prey. Sharp teeth organized and strengthened in rows plus a powerful jaw help the shark crack even the tough carapace, or shell, of adult turtles.
The green sea turtle on the other hand relies on protective measures. Its hard shell is one adaptation that makes it difficult for predators to eat the soft body of the animal. As a result of their tick shells, the turtles sacrificed speed. The turtles still maintain a decent ability to swim as a result of their long flippers. They also have a slow metabolic system (because they are cold-blooded), this allows them to stay submerged for long periods of time.
beneficial or detrimental?
Beneficial: Tiger sharks control the population of green sea turtles. Green sea turtles graze on sea grasses, and coral. Both actions allow the environment to clear out overcrowded regions and prevent a domination of nutrients by any one species. However, if there are too many turtles, the grasses and coral will be overgrazed, causing many organisms to lose habitats and food sources.
The Bigeye trevally (fish) and the Cardinalfish (prey fish)
In order to catch the cardinalfish, Bigeye trevallies will hunt in schools. They developed a strategy of hunting that involves surrounding the prey school and herding them towards a reef.
the cardinalfish also swim in schools. In their case, it is for protection from predators.
In order to be coordinated, they have evolved special vibration sensors located along their lateral sides to detect each other's movements and stay in sync.
The bigeye trevally helps keep the number of cardinal fish in check. As a result the cardinalfish's food, algae and coral, will be less likely to overcrowd the ecosystem.