The Swimming Head

The Ocean Sunfish (Molidae) answers to many names, all of which in some way describe this mysterious oceanic nomad. In contrast to the English common name, the animal is usually known as “Moon-fish” in other languages like peixe lua in Portuguese, or Mondfisch in German, making reference to its large rounded shape.

An alternative German name, Schwimmender Kopf which translates in to “swimming head”, also pretty much nails it when describing the appearance of this odd-looking creature. The head of the sunfish, which contains large peering eyes and a round gaping mouth, is infused with the rest of the body giving the impression that the animal is one giant floating face. It’s flattened, oval-shaped body can be up to 3.3m high and the animal is more or less as tall as it is long when it stretches out its dorsal and ventral fins. Despite being considered the largest of all bony fish, the animals skeleton largely consists of cartilage tissue, which is lighter than bone and has allowed the species to grow to a size that would otherwise seem impractical for most bony fish. It also lacks a swim bladder and its skin is not covered in scales but instead by denticles covered in a layer of mucus. This gives the greyish skin of the animal a partially rough texture resembling millstone, which is where the scientific name Mola originates from.

These generalist feeders are thought to actively hunt at depths of 200m and forage for a variety of prey including jellyfish, salps, small fish and fish larvae, crustaceans and squid. Between their dives, the animals ascend to the surface and linger there for a while to sunbathe, often even basking in a horizontal position to catch as much sun as possible. This was the habit which earnt them their English common name, Sunfish, and the sunniest part of the water column also happens to be the most dangerous place for this animal since it is most vulnerable to predation by sharks, seals or toothed whales.

I now explained just a few of the many names given to this fish and its behaviour is equally multi-faceted. Sunfish are usually observed cruising lethargically through the ocean but can also engage in short speed-bursts to hunt or flee. The animals also tend to be quite timid during an encounter but occasionally get curious and approach boats or divers in the water. These huge fish have also been observed breaching up to 3m into the air in an effort to clean their skin, which is known to host up to 40 different species of parasites.

Recently Mola mola has been split into two species; Mola mola and Mola alexandrini both of which occur in Madeira and around Macaronesia. Like all our sightings, Sunfish sightings occur at the surface where, at first, their dorsal fin often tricks us into thinking we are encountering one of their prime predators, a shark. The sculling movement of the fin then gives the animal away and a careful approach can often enable us to enjoy beautiful moments with this generally timid, gentle creature.

We had a rather sad sighting with a Mola mola which is largely outnumbered with peaceful encounters with these lovely giants, a few of which can be appreciated in Lobosonda’s Madeira Below series.

By Paula Thake