The ocean sunfish gets eaten alive

A two-tonne Mola mola will often float motionless at the surface while a sea lion methodically tears its fins off. These giant fish, which can grow as heavy as a pickup truck, lack a functional tail and move through the water by flapping long dorsal and anal fins like a clumsy bird. When a predator attacks, the sunfish has no means of escape and no way to fight back. It simply waits.

This passive behavior is less about a lack of survival instinct and more about the sunfish being a floating ecosystem. A single Mola mola can carry over 40 different species of parasites simultaneously. Their skin is so riddled with hitchhikers—including small crustaceans that burrow deep into their flesh—that they have developed a unique social contract with the surface world.

They float sideways, mimicking a piece of driftwood, to invite seagulls and other seabirds to land directly on their bodies. The birds act as a cleaning crew, plucking lice and worms out of the fish's skin. To the sunfish, losing a chunk of its flank to a sea lion is sometimes just the price of doing business in a body that serves as a mobile buffet.

They aren't just at the surface for cleaning, though. After diving nearly 600 meters into the frigid twilight zone to hunt jellyfish, their massive bodies lose critical heat. They lie flat on the surface to 'thermal recharge,' using their enormous surface area to soak up the sun like a solar panel.

Despite being eaten alive by everything from orcas to seals, the species survives through sheer mathematical defiance. A single female can release 300 million eggs at once, more than any other vertebrate on Earth. Every sunfish starts its life the size of a pinhead, encased in a spiked transparent bubble, before ballooning to 60 million times its birth weight.

Because their skin is essentially a thick layer of rough, bony collagen, many predators eventually grow bored and abandon the carcass before the fish actually dies.