Back in 1963, Paine began prying ochre starfish off a rocky beach in Washington and hurling them into the sea. After a year, the mussels that the starfish would normally have eaten had overrun the beach, turning a wonderland of limpets, anemones, and barnacles into a monoculture of black gaping shells.
The experiment was ground-breaking. It showed that not all species are equal, and that some — like the starfish—are secret lynchpins of the natural world. Their absence can ripple outwards, triggering the rise and fall of connected species and can even reshape the landscape. For example, when sea otters vanish, the sea urchins they eat transform lush forests of kelp into desolate barrens, dooming the fish, crabs, and other animals that once lived there. Paine called these ripples “trophic cascades”, and he billed the animals behind them — the starfish, otters, and others — as “keystone species”, after the central stone that stops an arch from collapsing. These concepts are so familiar today that we take them for granted, but we didn’t always know about them. We only do because of Paine. [Continue reading…]