A rare event was recently spotted in the cool waters of Cape Town - a massive ocean sunfish (Mola mola) leaping completely out of the water! You might have already seen it - photographs by Aly Ison have been widely circulated online after capturing this incredible moment near South Africa's Glencairn a few days ago (to our knowledge, this is one of just a few sunfish breaches ever photographed)!
Sunfish have a reputation for being cumbersome and sluggish - but this isn't truly fair. When sunfish are in the "human sphere" it's usually when they are resting - basking in the sun, or simply mulling around while digesting. But, we must remember that these massive fish are actually very active predators, and are capable of high speeds and great agility when diving hundreds of meters to find prey... or when rocketing back to the surface to get out of the cold depths as quickly as possible.
With this speed, comes the ability to leap clear out of the water. This is an event quite rarely seen by humans, and even more rarely photographed, but there have been a few cases of unlucky people being accidentally injured by flying sunfish. So, the question is, if they "can" breach, why is it so rare compared to animals like whales, seals and dolphins that breach regularly?
The truth is that scientists aren't completely sure. It is unlikely that sunfish use breaching for communications or "play" the way that many marine mammals do, or for "porpoising" like penguins and tuna, and the most plausible explanation seems to be that this behaviour is a way for sunfish to remove parasites.
Because sunfish cover such huge distances in their ocean wanderings, and move between the various trophic levels of the ocean with ease, there are a number of parasites and other hitchhiking organisms that tag a ride on sunfish for easy transport to different parts of the ocean where they need to complete their lifecycle. More than 50 different parasites are known to live on Mola molas!
Parasites are harmful to the sunfish, and even relatively benign hitchhikers can still damage a sunfish's skin and protective mucus layer in an attempt to cling on. To remove these parasites, sunfish have often been observed resting on their sides on the water's surface and allowing seabirds to walk on them, pecking off parasitic worms!
So, if a sunfish has a burst of speed, it might just use it to jump out of the water and knock some of these parasites off with a SMACK!