A Mola Mola! I love the way the beach is always giving us interesting hints and glimpses of what goes on in the depths and interesting mysteries to solve. This week, a huge fish washed up on our shore. Mark and Toni Beischel texted me a pic, and I had to run right down to the beach to see it for myself!
It was certainly a big fish. This one was at least 5 feet long and in relatively good condition. We could rinse off the eyeball (which seemed pretty fresh) and the rest of the skin. The skin was incredibly rough, like sandpaper. When we lifted the fin, it was clear that this was a fish with bones. In fact, it is the world’s largest bony fish, and found in temperate and tropical oceans around the world.
More about a Mola Mola (and underwater footage).
Research turned up a lot of interesting information about this fish. There are a bunch of youtube videos online, but this one from National Geographis is one of my favorites.
Several friends mentioned that they have seen them basking: swimming sideways on the surface of the ocean. One hooked one while fishing! And Josephine Humphreys found an article from Tuesday, Dec 11, 1973: Charleston’s Evening Post reporting a beached sunfish on Sullivan’s Island. It mentioned 12 times Mora-mora had washed up on the beach.
Largest bony fish in the ocean
When we lifted the fin, it was easy to feel that there was a bony structure in it. These fish can be huge~ 14 feet, and they are the largest bony fish in the sea. Whales, and sharks are larger, but they are mammals and cartilaginous fish. And along with sea lions, those whales and sharks are also the only predators of adult Mola Mola.
Predators of Jellyfish, Plankton, and Siphonophores
One of the most interesting facts I turned up in my initial research was that Mola Mola eat jellyfish, plankton, and siphonophores like Portuguese Man O’ War! Since we had so many of those purply bubbles on the beach about 10 days ago, it makes me wonder if the Mola Mola drifted in on the same currents.
They have a unique style of eating: they suck jellyfish and small vertebrates in and out, grinding them with that large tongue (they have no teeth) until the particles are small enough to ingest. Apparently they can digest those stinging cells from jellyfish and siphonophores because their digestive tract is lined with a protective mucus.
Parasites can be numerous
Many articles referenced the way the slow moving fish attracts parasites. There might be 40 different kinds of parasites on the skin of each fish, and they have to find ways to keep those parasites in check. Some check in to a spa treatment along a reef, where cleaner fish eat the parasites off them. Others sunbathe so that gulls can pick off some of the parasites. And some leap into the air so that when they splash down the parasites will be dislodged.
No visible cause of death
There was no clear cause of death like a shark bite or a propeller strike, but it’s possible a plastic bag was mistaken for a prey item and ingested, or that the sudden drop in temperatures with the freeze last week was faster than the fish could accommodate.
Impressive odds for reproductive success
Several sources mentioned the incredible fecundity of this fish: they lay the most eggs of any vertebrate: 300 million eggs a season. I am having a hard time getting my head around 300,000,000. And the eggs aren’t microscopic: they’re each 1.3 mm. When they hatch, the tiny fish swim together for protection.
The Monterey Bay Aquarium describes the ability of this fish to grow exponentially: “A mola hatches from a tiny egg but grows to weigh more than a pickup truck, increasing its weight 60 million times along the way. That’s the equivalent of a 1-gram tadpole turning into a 60-ton frog! “
Where are the scavengers?
While our fish has dried out some in the 48 hours it has been on the beach, it’s still relatively intact. We have several scavengers on the island that would normally be all over a carcass on the beach: crows, vultures, eagles, and coyotes~ this one seems relatively untouched. Like the fish itself, it’s a mystery we’ll keep watching!