Living together
Many animals live together in groups. When fish do this, it is called a shoal, and if the fish swim in the same direction, it is called a school. Some other words for when animals live in groups are flock, herd, gaggle and swarm. Even though the names for this way of life are different, the aim is often the same: it has several advantages!
A large school of sardines.
Photo: Colourbox
Wildebeests lives together in herds on the savannah.
Photo: David-Ryder-Colourbox
A large flock of starlings.
Photo: Jørgen-Flemming-Colourbox
Migratory locusts move in large swarms on Madagascar.
Photo: Iwoelbern-CC-BY-SA
Protection against predators
The main advantage of living in a shoal is protection against predators. It is hard for a predator to distinguish one individual in a large shoal of fish. The predator doesn’t know where to fix its gaze and gets confused. Living in a shoal also reduces the stress level for the participating fish. A lone fish that gets separated from its shoal becomes more stressed when danger threatens than the fish that stays with the shoal. This also makes it easier for the fish in the shoal to recover when the danger is over.
Piranhas live and hunt together in shoals.
Photo: Andrey-Armyagov-Colourbox
The Scalloped Hammerhead shark is one of a few species of shark that hunt together in shoals.
Photo: Xvic-CC-BY-SA
Hunting together
It’s also easier to hunt in a group than by yourself, even though this means there are more mouths to feed. Living in a shoal also makes it easier to find a partner to mate with, compared with what it’s like for fish that live alone.