When you think of a fish, the Mola mola is probably not what you’d picture. This strange fish has a somewhat circular body that is flattened from side-to-side with no caudal (tail) fin and rudder-like top and bottom fins, which the fish flaps to swim. Mola molas are found in temperate (cool) and tropical waters worldwide and are commonly seen on Hornblower Whale Watching trips off San Diego. It is also called the ocean sunfish due to its habit of lying on its side at the water’s surface. This bizarre behavior may help a mola mola warm up after a deep dive or be done to invite seabirds to peck parasites off its skin. The mola mola also often basks near kelp paddies or in kelp beds to allow small fishes to pick off parasites.
The mola mola is the world’s heaviest bony fish, reaching a maximum weight of 5,000 pounds (2,250 kg)! It remarkably attains this great weight on a diet tons of jellyfish, but also occasionally eats small fishes, squid and other gelatinous creatures such as salps. Although mola mola are not endangered, they often eat floating plastic bags—mistaking them for jellyfish prey—which can choke or suffocate these fish. You can help mola molas by making sure your trash (including plastic bags) is always properly disposed of so that it can’t reach the sea. Even better, bring and use reusable bags whenever you are grocery shopping. By taking these simple steps, you can help keep the oceans healthy for mola molas and other ocean wildlife.