Molidae

"Molid" redirects here. For the Romanian village, see Vama, Suceava.

Molas or ocean sunfishes
Ocean sunfish, Mola mola
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Actinopterygii
Order:	Tetraodontiformes
Family:	Molidae
Genera
Masturus Mola Ranzania See text for species.

Molidae is the family of the molas or ocean sunfishes, unique fish whose bodies come to an end just behind the dorsal and anal fins, giving them a "half-a-fish" appearance. They are also the largest of the ray-finned bony fishes, with the ocean sunfish Mola mola recorded at up to 3.3 metres (11 ft) in length and 2 tonnes (2.2 short tons) in weight.^[1]

They have the fewest vertebrae of any fish, only 16 in Mola mola. They have fairly rough skin. Also, they completely lack all caudal bones, and most of their skeleton is made of cartilage. There are no bony plates in the skin; it is, however, thick and dense like cartilage. They also lack a swim bladder. The meat contains the same toxin as in pufferfish and porcupine fish, but not in the same amounts.^{[citation needed]}

Molids mostly swim by using their anal and dorsal fins, the pectoral fins are probably just stabilizers. To steer, they squirt a strong jet of water out of their mouth or gills.^[1] They can also make minor adjustments in the orientation of the anal fin or the dorsal fin so as to control the amount of force it produces and the angle at which the force is produced. In this respect, they use their fins much like a bird uses its wings.^[2]

Molids are said to be able to produce sound by grinding their pharyngeal teeth, which are long and claw-like. Typical of a member of Tetraodontiformes, their teeth are fused into a beak-like structure, making it impossible for them to close their mouth. Despite this, they feed mainly on soft-bodied animals, such as jellyfish and salps, although they will also take small fish or crustaceans.^[1]

Behavior

Molids have been filmed interacting with other species. Since molids are susceptible to skin parasites, they make use of cleaner fish. A molid in need of cleaning will locate a patch of floating algae or flotsam that is home to half moon perch. The molid then signals a readiness for cleaning by swimming almost vertically with its head near the surface of the water. It waits for the smaller cleaner fish to feed on the parasite worms. Similarly, the molid may break the surface of the water with its dorsal fin and beak to attract the attention of a gull or similar seabird. The seabird will then dig worms and other stubborn parasites out of the molid's skin.^[2]

Species

The family is small, consisting of just five species in three genera:

• Genus Masturus
  • Sharptail mola, Masturus lanceolatus
  • Masturus oxyuropterus
• Genus Mola
  • Ocean sunfish, Mola mola
  • Southern sunfish, Mola ramsayi
• Genus Ranzania
  • Slender sunfish, Ranzania laevis

References

1. ^ ^{a b c} Keiichi, Matsura & Tyler James C. (1998). Paxton, J.R. & Eschmeyer, W.N.. ed. Encyclopedia of Fishes. San Diego: Academic Press. p. 231. ISBN 0-12-547665-5. 
2. ^ ^{a b} Alastair Fothergill (director), David Attenborough (narrator) (2001-09-12). Blue Planet, Seas Of Life Episode 3 (Television series). BBC Worldwide, Ltd.. ISBN 0-563-38498-0. http://www.imdb.com/title/tt0296310/. 

External links

• FishBase info for Molidae
• The Open Ocean MarineBio.org. Updated: 28 August 2011.