A Head of its Time
After the fall of the dinosaurs, there weren't too many large sea creatures to worry about. In fact, you could avoid being eaten by getting too big to fit in a predator's mouth. One Order of fish, the Tetraodontiformes, did just that. The Triggerfish developed a large spine on their back to cheaply increase their size and stab the mouths of predators. The Pufferfish became inflatable, changing their size as they seem fit. And our Molas, also called sunfish, grew to incredible size.
Alright, yeah it looks pretty weird. They get to be about 4 meters long and 4 meters tall. The largest mola caught was a Mola alexandrini weighing in at 6,050lbs. They are the largest bony fish, despite and because of their mostly cartilaginous skeleton. Cartilage is lighter than bone, making it easier and less expensive to move around. It's great that they have that going for them because nothing else about this fish screams "mobile." They have a shortened, fused spine. They have no muscles on the sides of their bodies to swish their tail back and forth like other fish. They have a tail, but it never develops. They have no swim bladder to control their bouyancy. Just two, highly-muscularized fins at the top and bottom. You wouldn't be wrong to call it a head with wings.
You see that neat little space between the head and the bottom fin? That's where all of the fish's organs are kept. Notably, they've got no ribs! What is keeping this massive burger from being eaten? It's their disgusting skin. They don't have scales like most fish. Instead they have rectangular "dermal denticles", or skin teeth. Seriously, the same idea as your teeth. They've got blood vessels and nerves, even an enamel. All sharks have these too. They reduce drag and offer protection.
Biting into something and getting that tooth to skin tooth action isn't the worst of it. Underneath that layer is about three inches of elastic, spongey collagen matrix. It's so rigid that it's almost like an exoskeleton. This low-density, gelatinous "blubber" is very nutrient poor and unappetizing, BUT it makes our massive fish neutrally bouyant or effectively weightless in the water. And if you take a big bite, that's like 6 inches of collagen to bite through. I can't imagine anything wanting to eat our friend.
Oh.
Uh, anyways. The mola eats jellyfish, comb jellies, and siphonophores; low nutrient gooey stuff. To keep thier bulk up, they've got to eat a lot. Quite smartly, their prey has a daily cycle of rising to eat at night and sinking right below the level the light reaches during the day. Our titan goes down their multiple time a day, but it's cold. Here's where they get the name Sunfish. They can't produce their own body heat, so like a lizard, they lay in the Sun!
And while they're chilling, they might as well get cleaned. They'll flap their fins to attract birds to come pick at their parasites. When they warm up again, it's right back down to the depths in search of food. As a matter of fact, any fish that does have a swim bladder, which is around 95% of them, would pop from changing pressure so quickly so many times a day.
I first saw it in Endless Ocean for the Wii as a kid. I did my first night dive after hours of playing the game (I was scared) and I did it at the first area you ever go to because I knew exactly what to expect. It was like nothing I had ever seen before!
That game was scary! It looks peaceful but being alone in the ocean was unsettling at best. Going out of my comfort zone and seeing this as a reward was everything and it stuck with me to this day. And then I'm in middle school watching youtube with my friend Walck and this video had us dying laughing. I've got nothing but good experiences with this animal. It can seem weird and stupid. That's true. But it wouldn't seem that way if there was anything else on this planet like it. Unique animal, situationally gorgeous, BIG: