Weird Wildlife Wednesday: A Big-Ass Fish with No Tail
This is the the Ocean Sunfish, it is the heaviest known bony fish and it almost weighs twice as much as my car. Large specimens can be as large as 4.2 meters from the dorsal fin to the anal fin, 3.1 meters from mouth to tail, or clavus, and weigh 2,268 kilograms.
This fish is my spirit animal. It hangs out in tropical waters, basking in the sun and snacking on the nutritionally poor jellyfish, requiring them to eat a lot. I wouldn’t necessarily want to be reincarnated as one of these sunfish though, they are wicked prone to parasite infestation.
The fish will breach up to three meters out of the water and thrash around to try to dislodge the parasites.
The skeleton of Ocean Sunfish is rather beautiful. It makes up for the complete awkwardness of the fish as it swims. This awkwardness is related to the fact that this fish swims by wiggling its dorsal and anal fins in the absence of a real formed tail. To determine the origins of the clavus, scientists at the Smithsonian Institution studied the developing skeletons of sunfish larvae and compared the development to that of a puffer fish, a related yet less modified species.
The research yielded no signs of an actual caudal fin, but instead demonstrated that the dorsal and anal fins actually grow together to create the clavus, or rudder-like pseudo tail, completely replacing an actual tail fin.