A sunfish (or mola) is any

fish Fish are aquatic, craniate, gill-bearing animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish as well as various extinct related groups. Approximately 95% of li ...

in the ''Mola''

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

(

family Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...

Molidae The Molidae comprise the family of the molas or ocean sunfishes, unusual fish whose bodies come to an end just behind the dorsal and anal fins, giving them a "half-fish" appearance. They are also the largest of the ray-finned bony fish, with the ...

). The fish develop their truncated, bullet-like shape because the back fin, with which they are born, never grows. Instead, it folds into itself as the creature matures, creating a rounded rudder called a clavus. ''Mola'' in Latin means "millstone" and describes the ocean sunfish's somewhat circular shape. They are a silvery color and have a rough skin texture. The mola is the heaviest of all the

bony fish Osteichthyes (), popularly referred to as the bony fish, is a diverse superclass of fish that have skeletons primarily composed of bone tissue. They can be contrasted with the Chondrichthyes, which have skeletons primarily composed of cartilag ...

, with large specimens reaching vertically and horizontally and weighing over .

Shark Sharks are a group of elasmobranch fish characterized by a cartilaginous skeleton, five to seven gill slits on the sides of the head, and pectoral fins that are not fused to the head. Modern sharks are classified within the clade Selachimo ...

s and rays can be heavier, but they are cartilaginous fish. Mola are found in temperate and tropical oceans around the world. They are frequently seen basking in the sun near the surface and are often mistaken for sharks when their huge dorsal fins emerge above the water. Their teeth are fused into a beak-like structure, and they are unable to fully close their relatively small mouths. Ocean sunfish can become infested with skin

parasite Parasitism is a close relationship between species, where one organism, the parasite, lives on or inside another organism, the host, causing it some harm, and is adapted structurally to this way of life. The entomologist E. O. Wilson has ...

s, so they will often invite small fish or even birds to feast on them. Sunfish will even breach the surface up to in the air, in an attempt to shake the parasites. They are clumsy swimmers, waggling their large dorsal and anal fins to move, and steering with their clavus. Their food of choice is

jellyfish Jellyfish and sea jellies are the informal common names given to the medusa-phase of certain gelatinous members of the subphylum Medusozoa, a major part of the phylum Cnidaria. Jellyfish are mainly free-swimming marine animals with umbrella- ...

, though they will eat small fish and huge amounts of

zooplankton Zooplankton are the animal component of the planktonic community ("zoo" comes from the Greek word for ''animal''). Plankton are aquatic organisms that are unable to swim effectively against currents, and consequently drift or are carried along by ...

and

algae Algae (; singular alga ) is an informal term for a large and diverse group of photosynthetic eukaryotic organisms. It is a polyphyletic grouping that includes species from multiple distinct clades. Included organisms range from unicellular mic ...

, as well. They are harmless to people, but can be very curious and will often approach divers. Their population is considered vulnerable, as they frequently are snagged in drift gill nets and can suffocate on sea trash, like

plastic bag A plastic bag, poly bag, or pouch is a type of container made of thin, flexible, plastic film, nonwoven fabric, or plastic textile. Plastic bags are used for containing and transporting goods such as foods, produce, powders, ice, magazines, c ...

s (which resemble jellyfish, their main food source).

Species

There are currently 3 recognized species in this genus: * '' Mola mola'' ( Linnaeus,

1758 Events January–March * January 1 – Swedish biologist Carl Linnaeus (Carl von Linné) publishes in Stockholm the first volume (''Animalia'') of the 10th edition of Systema Naturae, 10th edition of ''Systema Naturae'', the sta ...

) (Ocean sunfish) * '' Mola alexandrini'' ( Giglioli, 1883) (Southern sunfish) * '' Mola tecta'' Nyegaard ''et al''., 2017 (Hoodwinker sunfish)

References

Extant Miocene first appearances Marine fish genera Taxa named by Joseph Gottlieb Kölreuter {{tetraodontiformes-stub