Molidae

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Molidae
Temporal range: Upper Eocene–present [1]
Mola-mola-Lisboa-20051020.jpg
Mola mola
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Tetraodontiformes
Suborder: Tetraodontoidei
Family: Molidae
Bonaparte, 1832
Genera [2]

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 southern sunfish, Mola alexandrini, recorded at 4.6 m (15 ft) in length [3] and 2,744 kg (6,049 lb) in weight.

The family name comes from the ocean sunfish's scientific name Mola mola, both its genus name and epithet come from the Latin word mola for "millstone" because of its circular shape. [4]

Description

Sunfish skeleton photographed by Lewis Carroll Skeleton of the sun fish, 1857.jpg
Sunfish skeleton photographed by Lewis Carroll

Molidae have the fewest vertebrae of any fish, with only 16 in Mola mola. They also completely lack all caudal bones, and most of their skeleton is made of cartilage. No bony plates occur in the skin, which is, however, thick and dense like cartilage and is fairly rough. They also lack swim bladders.

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 mouths or gills. [5] 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. [6]

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 mouths. Despite this, they feed mainly on soft-bodied animals, such as jellyfish and salps, although they also take small fish or crustaceans. [5]

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 halfmoons. The molid signals a readiness for cleaning by swimming almost vertically with its head near the surface of the water, and 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. [6]

Fossil record

The known fossil history of Molidae extends back to the Eocene, with the genus Eomola containing the species E. bimaxillaria , known from the Upper Eocene of the North Caucasus. [1] The fossil genus Austromola containing one species, A. angerhoferi Gregorova, Schultz, Harzhauser & Kroh, 2009, is known from the Lower Miocene Ebelsberg Formation near Pucking, Austria. This species was a resident of the Paratethys Sea and is estimated to have reached a length around 320 cm (130 in). At least one fossil species of Mola, M. pileata (van Beneden, 1881), is known from the Upper and Middle Miocene of Europe with a possible second species known from the Lower Miocene of North Carolina, United States. The genus Ranzania has five known fossil species: R. grahami Weems, 1985 and R. tenneyorum Weems, 1985, both from the Middle Miocene Calvert Formation of Virginia, USA; R. zappai Carnevale, 2007 from the Middle Miocene of Italy; R. ogaii Uyeno & Sakamoto, 1994 from the Middle Miocene of Japan; and an as yet unnamed species from the Upper Miocene of Algeria. [7]

Species

Only five extant species in three extant genera are described:

RankMolid speciesCommon nameYearMass (kg)Total length
(m)
Clavus (pseudo-tail) appearanceShape of head and chinImage
1Mola mola Ocean sunfish 175823003.33ScallopedLess bumpy and less protruding
Portugal-Lisboa-Oceanario de Lisboa -P1170757 (25260836764).jpg
2Mola alexandrini Southern sunfish 202127443.0RoundedBumps on head and chin
Mola alexandrini (Bump-head Mola).jpg
3Mola tecta Hoodwinker sunfish 201718702.42Rounded with medial indentationNo lumps and bumps on head and chin
Mola tecta.jpg
4Masturus lanceolatus Sharptail mola 184020003.37Pointed projectionConvex forehead
Masturus lanceolatus.jpg
5Ranzania laevis Slender sunfish 1776NA1.0Slant and flatPointed and bump-less
Ranzania laevis2.jpg

Related Research Articles

<span class="mw-page-title-main">Tetraodontiformes</span> Order of fishes

The Tetraodontiformes are an order of highly derived ray-finned fish, also called the Plectognathi. Sometimes these are classified as a suborder of the order Perciformes. The Tetraodontiformes are represented by 10 extant families and at least 349 species overall; most are marine and dwell in and around tropical coral reefs, but a few species are found in freshwater streams and estuaries. They have no close relatives, and descend from a line of coral-dwelling species that emerged around 80 million years ago.

<span class="mw-page-title-main">Centrarchidae</span> Family of fishes

Centrarchidae, better known as sunfishes, is a family of freshwater ray-finned fish belonging to the order Perciformes, native only to North America. There are eight universally included genera within the centrarchid family: Lepomis, Micropterus, Pomoxis (crappies), Enneacanthus, Centrarchus, Archoplites, Ambloplites, and Acantharchus. A genetic study in 2012 suggests that the highly distinct pygmy sunfishes of the genus Elassoma are also centrarchids.

<span class="mw-page-title-main">Ocean sunfish</span> Species of fish

The ocean sunfish or common mola is one of the largest bony fish in the world. It was misidentified as the heaviest bony fish, which was actually a different species, Mola alexandrini. Adults typically weigh between 247 and 1,000 kg. The species belongs to the Mola genus, one of three in the Molidae family. It is native to tropical and temperate waters around the world. It resembles a fish head without a tail, and its main body is flattened laterally. Sunfish can be as tall as they are long when their dorsal and ventral fins are extended.

<span class="mw-page-title-main">Slender sunfish</span> Species of fish

The slender sunfish is a mola of the family Molidae, the only extant member of the genus Ranzania, found globally in tropical and temperate seas. Its length is up to 1 m (3.3 ft). Several stranding and mass stranding events have occurred on beaches near Albany, Western Australia.

Ranzania may refer to:

<span class="mw-page-title-main">Hardnose shark</span> Species of shark

The hardnose shark is a species of requiem shark, in the family Carcharhinidae, so named because of the heavily calcified cartilages in its snout. A small bronze-coloured shark reaching a length of 1.1 m (3.6 ft), it has a slender body and a long, pointed snout. Its two modestly sized dorsal fins have distinctively elongated rear tips. The hardnose shark is widely distributed in the western Indo-Pacific, from Kenya to southern China and northern Australia. It inhabits warm, shallow waters close to shore.

<span class="mw-page-title-main">Triacanthidae</span> Family of fishes

Triacanthidae, commonly known as triplespines or tripodfishes, is a family of Indo-Pacific fishes. It is classified in the order Tetraodontiformes, along with the pufferfishes and the ocean sunfish. The family consists of seven species in four genera, in addition to one extinct genus that only is known from fossils.

<i>Mola</i> (fish) Genus of fishes

A sunfish, also called a mola, is any fish in the genus Mola. The fish develop their truncated, bullet-like shape because the back fin, which is present at birth, 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.

<i>Carcharias</i> Genus of sharks

Carcharias is a genus of mackerel sharks belonging to the family Odontaspididae. Once bearing many prehistoric species, all have gone extinct with the exception of the critically endangered sand tiger shark.

<i>Eospinus</i> Species of fish

Eospinus daniltshenkoi is an extinct tetraodontid bony fish from the Eocene. Its fossils are from the Danata Formation lagerstatten of Ypresian Turkmenistan.

<i>Eomola</i> Extinct genus of fishes

Eomola is an extinct genus of sunfish from the upper Eocene. Its fossils have been found in Russia. Eomola was described in 1992 by James Tyler and Alexandre Bannikov, and the type species is E. bimaxillaria.

<i>Caranx</i> Genus of fishes

Caranx is a genus of tropical to subtropical marine fishes in the jack family Carangidae, commonly known as jacks, trevallies and kingfishes. They are moderate- to large-sized, deep-bodied fishes which are distinguished from other carangid genera by specific gill raker, fin ray and dentition characteristics. The genus is represented in the Pacific, Indian and Atlantic Oceans, inhabiting both inshore and offshore regions, ranging from estuaries and bays to deep reefs and offshore islands. All species are powerful predators, taking a variety of fish, crustaceans and cephalopods, while they in turn are prey to larger pelagic fishes and sharks. A number of fish in the genus have a reputation as powerful gamefish and are highly sought by anglers. They often make up high amounts of the catch in various fisheries, but are generally considered poor to fair table fishes.

<i>Cantherhines dumerilii</i> Species of fish

Cantherhines dumerilii is a species of fish in the family Monacanthidae, the filefishes. Its common names include whitespotted filefish, barred filefish, orange-fin file, and yelloweye leatherjacket. It is distributed in the Indian and Pacific Oceans where it is found on coral reefs.

<span class="mw-page-title-main">Sharptail mola</span> Species of fish

The sharptail mola is a species of mola found circumglobally in tropical and temperate waters. It is similar in appearance to the ocean sunfish, but can be distinguished by the projection on its clavus (pseudo-tail). Other common names include sharpfin sunfish, point-tailed sunfish, and trunkfish. Rarely encountered, very little is known of the biology or life history of the sharptail mola. It has recently become important to commercial fisheries operating off eastern Taiwan. This species is the only member of its genus.

<i>Phareodus</i> Extinct genus of bony fishes

Phareodus is a genus of freshwater fish from the Paleocene to the Eocene of Australia, Europe and North and South America.

<span class="mw-page-title-main">Giant sunfish</span> Species of fish

The giant sunfish or bumphead sunfish, , is a fish belonging to the family Molidae. It is closely related to the more widely known Mola mola, and is found in the Southern Hemisphere. With a specimen found dead near the Azores in 2021 weighing in at 2744 kg it is the largest extant bony fish species in terms of maximum recorded mass by a wide margin. It can be found basking on its side occasionally near the surface, which is thought to be used to re-heat themselves after diving in cold water for prey, recharge their oxygen stores, and attract gulls to free them of parasites.

<span class="mw-page-title-main">Carybdea murrayana</span> Species of jellyfish

Carybdea murrayana Haeckel, 1880, also previously known as Carybdea branchi, the South African box jellyfish, is a venomous species of cnidarian, in the small family Carybdeidae within the class Cubozoa.

<i>Austromola</i> Extinct species of ocean sunfish

Austromola is an extinct genus of ocean sunfish. It contains a single species, A. angerhoferi, known from the Lower Miocene Ebelsberg Formation near Pucking, Austria. It is thought to be the sister taxon to Mola and Masturus.

<i>Mola tecta</i> Species of fish

Mola tecta, the hoodwinker sunfish, belongs to the family Molidae and genus Mola. It is closely related to the more widely known ocean sunfish. The Latin word "tecta" means hidden. The word "hidden" was adopted for the name because the fish has blended in among other species of sunfish for a long time and has only been discovered recently. Discovered on a beach near Christchurch, New Zealand, in 2015, it was the first new species of sunfish to be identified in 130 years. Mola tecta are mostly discovered in the temperate region of the Southern Hemisphere in the water near Australia, New Zealand, Southern Chile and Southern Africa. It was first described by Marianne Nyegaard, a marine scientist who studied ocean sunfish for her PhD.

Marianne Nyegaard is a Danish marine biologist who specializes in the study of ocean sunfish. She is known for identifying the ocean sunfish species Mola tecta.

References

  1. 1 2 Tyler, James C.; Bannikov, Alexandre F. (1992). "New genus of primitive ocean sunfish with separate premaxillae from the Eocene of Southwest Russia (Molidae, Tetraodontiformes)". Copeia. 1992 (4). Copeia, Vol. 1992, No. 4: 1014–1023. doi:10.2307/1446631. JSTOR   1446631.
  2. Matsuura, K. (2014): Taxonomy and systematics of tetraodontiform fish: a review focusing primarily on progress in the period from 1980 to 2014. Ichthyological Research, 62 (1): 72-113.
  3. "Massive Huge Sun Fish off of Portugal 15 foot plus". YouTube. 6 October 2015. Retrieved 1 March 2019.
  4. Scharpf, Christopher; Lazara, Kenneth J. (12 June 2023). "Family TETRADONTIFORMES" (PDF). The ETYFish Project. Retrieved 30 October 2023.
  5. 1 2 Matsuura, K. & Tyler, J.C. (1998). Paxton, J.R. & Eschmeyer, W.N. (eds.). Encyclopedia of Fishes. San Diego: Academic Press. p. 231. ISBN   0-12-547665-5.
  6. 1 2 Fothergill, A. (director), Attenborough, D. (narrator) (2001-09-12). Blue Planet, Seas Of Life Episode 3 (Television series). BBC Worldwide, Ltd. ISBN   0-563-38498-0.
  7. Ruzena, G., Schultz, O., Harzhauser, M., Kroh, A. & Ćorić, S. (2009): A Giant Early Miocene Sunfish from the North Alpine Foreland Basin (Austria) and its Implication for Molid Phylogeny. Journal of Vertebrate Paleontology, 29 (2): 359–371.
  8. "World's heaviest bony fish identified and correctly named". Springer.com. Retrieved 1 March 2019.
  9. "Mola alexandrini". Fishesofaustralia.net.au. Retrieved 1 March 2019.
  10. "Redescription of the bump-head sunfish Mola alexandrini (Ranzani 1839), senior synonym of Mola ramsayi (Giglioli 1883), with designation of a neotype for Mola mola (Linnaeus 1758) (Tetraodontiformes: Molidae)". Researchgate.net. Retrieved 1 March 2019.