Pictures courtesy of http://www.earthwindow.com/mola.html

After hearing me excitedly mentioning again and again that I have seen my first Mola mola during my recent diving trip to Bali a friend asked me what's so exciting about them. Well, Mola mola is THE thing to see underwater in Nusa Penida. These unusual fish don't stop by there too often, only in certain times of the year, so there are seasons in Bali when divers flock together in certain dive sites waiting to spot a Mola mola or two if they're lucky.

Mola mola is the latin word for the ocean sunfish. The word mola means millstone. The fish earns its name due to its exotic and bizarre look. The body is large and has a flat round shape. It doesn't have a true tail fin; instead it has clavus, which is formed of extensions of dorsal and anal fins. All in all it makes the fish looks like it's formed entirely out of a head, which is why it is sometimes dubbed headfish.

The unusual looking fish is the world's largest known bony fish. With other fishes, Mola mola belongs to the kingdom Animalia, Phylum Chordata and Subphylum Vertebrata. Fish are vertebrates that live in water, breathe with gills and are cold-blooded. They can be divided into 3 classes: 1. Agnatha, jawless fish such as the hagfish and lampreys; 2.  Chrondrichthyes, fish whose skeleton is made of cartilage such as sharks, rays and skates; and 3. Osteichthyes, fish whose skeleton is composed mostly of bone.

The bony fish Osteichthyes, are then further classified into two main groups called the ray-finned  (Actinopterygii) and the lobe-finned subclasses. Mola mola belongs to Actinopterygii subclass, Tetraodontiformes order (which includes pufferfish, boxfish, triggerfish and filefishes) and the Molidae family. The family has 6 species i.e. Mola mola (ocean sunfish), Masturus lanceolatus (Sharptail mola) and Ranzania laevis (Slender sunfish), Mola ramsayi (southern sunfish), Amblypharyngodon atkinsonii and Amblypharyngodon mola

Mola mola or the ocean sunfish are entirely different from freshwater sunfish (which includes the families of bass). They are called ocean sunfish because of their habit of lying at the surface almost motionless as if they were sunning themselves. They do that to give a chance for birds to pick parasites off their skin, like in Southern California where seagulls often seen pecking at Mola mola. Mola mola have rough and leathery skin which hosts more dermal parasites than that of any other marine creature.

Actually Mola mola inhabit the mesopelagic zone down to about 1000 meters and they live most commonly about 300m deep. However in Bali Mola mola often come close to the reef at certain cleaning stations where groups of the bannerfishes (Heniochus diphreutes), angelfishes and butterflyfishes peck at them, eating the parasites that infest their skin. The Mola mola 'season' around Nusa Penida is around August.
 
  Pictures courtesy of http://www.earthwindow.com/mola.html

Mola mola often swim upright and close to the surface that their dorsal fin projects above the water like a large shark fins, therefore they are often mistaken for sharks. These ocean sunfish are commonly friendly towards people, such as divers who venture into their habitat.

Mola mola are also commonly observed jumping out of the water. They can jump 10 feet into the air and recently a family reported in BBC News that a Mola mola had jumped into the air and landed in their boat on top of their kid.

Mola mola can produce more than 300 million eggs, each about 2 to 3mm large. More than any other known vertebrate. They are thought to live for over 10 years but some other website said they can get over 100 years old. However just like many marine creatures they are probably in danger of dwindling population from the increase pressure of fishing by human and other environmental factors.

Scientists have not yet understood the biology of Mola mola and their distribution, hence they do not know yet for certain whether the population is dwindling, however a recent tagging by satellite to monitor the population of Mola mola in Californian waters show that there are consistent early indications that the population size has recently been reduced – possibly due to fishing pressure.

Mola mola are found in warm and temperate zones of all oceans, but prefers open ocean. They eat jellifish, zooplankton, squid, and crustaceans, foraging for food both at the surface, among floating weeds, or on the sea floor and in deep water. Their predators are  great whites, orcas, sea lions, dolphins and marlins.

Man is also an enemy. Although Mola mola have never been hunted commercially by human and are not highly desirable as food since their meat may contain the same toxin as puffers and porcupine fish, they are eaten in Europe and Japan and their liver oil is considered important. They are also used in Chinese medicine. In California Mola mola make up more than 25 percent drift net bycatch.

A discussion forum even reported that there is an annual Sunfish feast festival in Taiwan, where government limits the catch to 66 Mola mola a year.  Disgusting! No wonder it's not easy for us, divers, to sight the unusual looking, unique and wonderful Mola mola!

Jakarta, 25 September 2005

The article above was summed from the following sites:
http://en.wikipedia.org/wiki/Ocean_sunfish
http://www.oceansunfish.org/lifehistory.html
http://bonita.mbnms.nos.noaa.gov/reports/2003/eco/ocean.html
http://www.earthwindow.com/mola.html
http://www.amonline.net.au/fishes/fishfacts/fish/mola.htm
http://www.starfish.ch/reef/mola-sunfish.html
http://www.spart5.k12.sc.us/techtraining/teacher/webpages/SCFish/fish_classification.htm
http://www.angelfire.com/mo2/animals1/tetra/oceansunfish.html
http://www.fishbase.org/Summary/SpeciesSummary.php?id=1732

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