The sharptail mola (''Masturus lanceolatus'') is a

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriat ...

of mola found circumglobally in

tropical The tropics are the regions of Earth surrounding the Equator. They are defined in latitude by the Tropic of Cancer in the Northern Hemisphere at N and the Tropic of Capricorn in the Southern Hemisphere at S. The tropics are also referred to ...

and

temperate In geography, the temperate climates of Earth occur in the middle latitudes (23.5° to 66.5° N/S of Equator), which span between the tropics and the polar regions of Earth. These zones generally have wider temperature ranges throughout ...

waters. It is similar in appearance to the

ocean sunfish The ocean sunfish or common mola (''Mola 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 . The sp ...

(''Mola mola''), but can be distinguished by the projection on its clavus (pseudo-tail). Other

common name In biology, a common name of a taxon or organism (also known as a vernacular name, English name, colloquial name, country name, popular name, or farmer's name) is a name that is based on the normal language of everyday life; and is often contrast ...

s include sharpfin sunfish, point-tailed sunfish, and trunkfish.McGrouther, M. (2007)
Sharptail Sunfish, ''Masturus lanceolatus''
''Australian Museum Fish Site''. Rarely encountered, very little is known of the biology or life history of the sharptail mola. It has recently become important to

commercial fisheries Commercial fishing is the activity of catching fish and other seafood for commercial profit, mostly from wild fisheries. It provides a large quantity of food to many countries around the world, but those who practice it as an industry must often p ...

operating off eastern

Taiwan Taiwan, officially the Republic of China (ROC), is a country in East Asia, at the junction of the East and South China Seas in the northwestern Pacific Ocean, with the People's Republic of China (PRC) to the northwest, Japan to the no ...

. This species is the only member of its

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...

Distribution and habitat

The distribution of the sharptail mola is worldwide in tropical and temperate waters. They are primarily inhabitants of the epipelagic zone, but are rarely sighted at the surface, with many of those appearing to be ill and

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 h ...

-ridden. During the day, they spend most of their time at depths of , preferring water temperatures above 20 °C, but making repeated dives into cooler, deeper water, possibly to feed or to avoid

predator Predation is a biological interaction where one organism, the predator, kills and eats another organism, its prey. It is one of a family of common feeding behaviours that includes parasitism and micropredation (which usually do not kill t ...

s. At night, they spend most of their time between . They have been sighted in the

mesopelagic zone The mesopelagic zone ( Greek μέσον, middle), also known as the middle pelagic or twilight zone, is the part of the pelagic zone that lies between the photic epipelagic and the aphotic bathypelagic zones. It is defined by light, and begins a ...

to a depth of , but may descend to over . One tagged individual in the

Gulf of Mexico The Gulf of Mexico ( es, Golfo de México) is an ocean basin and a marginal sea of the Atlantic Ocean, largely surrounded by the North American continent. It is bounded on the northeast, north and northwest by the Gulf Coast of the United ...

moved an average of a day.

Description

One of the largest

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 cartil ...

es, the sharptail mola can measure up to long and weigh . It has an oval body with an evenly convex forehead profile. The eyes are placed more forward on the head than in the genus ''Mola''. The

teeth A tooth ( : teeth) is a hard, calcified structure found in the jaws (or mouths) of many vertebrates and used to break down food. Some animals, particularly carnivores and omnivores, also use teeth to help with capturing or wounding prey, ...

in both jaws are fused into

beak The beak, bill, or rostrum is an external anatomical structure found mostly in birds, but also in turtles, non-avian dinosaurs and a few mammals. A beak is used for eating, preening, manipulating objects, killing prey, fighting, probing for fo ...

-like plates. The

dorsal Dorsal (from Latin ''dorsum'' ‘back’) may refer to: * Dorsal (anatomy), an anatomical term of location referring to the back or upper side of an organism or parts of an organism * Dorsal, positioned on top of an aircraft's fuselage * Dorsal c ...

and

anal fin Fins are distinctive anatomical features composed of bony spines or rays protruding from the body of a fish. They are covered with skin and joined together either in a webbed fashion, as seen in most bony fish, or similar to a flipper, as see ...

s are placed posteriorly, and the base of the dorsal fin is longer than that of the anal fin. In place of a

caudal fin Fins are distinctive anatomical features composed of bony spines or rays protruding from the body of a fish. They are covered with skin and joined together either in a webbed fashion, as seen in most bony fish, or similar to a flipper, as se ...

, the dorsal and anal fins merge into a clavus, formed by 18-20

fin ray Fins are distinctive anatomical features composed of bony spines or rays protruding from the body of a fish. They are covered with skin and joined together either in a webbed fashion, as seen in most bony fish, or similar to a flipper, as see ...

s. The central rays in the clavus are supported by the last

vertebra The spinal column, a defining synapomorphy shared by nearly all vertebrates, Hagfish are believed to have secondarily lost their spinal column is a moderately flexible series of vertebrae (singular vertebra), each constituting a characteristi ...

and form an elongated triangular lobe; some authors believe these rays to be remnants of the larval caudal fin, though this is disputed. Their

skin Skin is the layer of usually soft, flexible outer tissue covering the body of a vertebrate animal, with three main functions: protection, regulation, and sensation. Other animal coverings, such as the arthropod exoskeleton, have different ...

is covered with small

dermal denticle A fish scale is a small rigid plate that grows out of the skin of a fish. The skin of most jawed fishes is covered with these protective scales, which can also provide effective camouflage through the use of reflection and colouration, as ...

s that are finer than those of the ocean sunfish. Their coloration is silvery with the upper parts of the sides grayish brown to blackish. The sides may bear ill-defined dark spots. The dorsal and anal fins are slate gray, while the clavus may have pale blotches.Bigelow, H.B. & Schroeder, W.C. (1953)
Sharp-tailed sunfish
''Fishes of the Gulf of Maine''. This species is distinguished from the similar '' Masturus oxyuropterus'' by its prominent chin, the lack of a concavity above the eyes, and the unequal lengths of the dorsal and anal fin bases. These two forms may represent different sexes of the same species.

Biology and ecology

Robert Collett Robert Collett (2 December 1842 – 27 January 1913) was a Norwegian zoologist. Collett was director and curator of the Zoological Museum at University of Oslo. Robert Collett was born at Christiania (now Oslo), Norway. He was the eldest child ...

, who examined some of the first known specimens of sharptail mola, speculated they might represent abnormal ocean sunfishes that had retained larval characteristics. However, the caudal projection is now known to be a secondary development that follows the loss of the primary

tail The tail is the section at the rear end of certain kinds of animals’ bodies; in general, the term refers to a distinct, flexible appendage to the torso. It is the part of the body that corresponds roughly to the sacrum and coccyx in mammal ...

. The swimming mode of the sharptail is similar to that of other ocean sunfishes, using sculling motions of its long dorsal and anal fins to propel itself through the water. The anal fin moves more extensively than the dorsal fin. The small pectoral fins move constantly to control pitch, while the clavus is employed as a

rudder A rudder is a primary control surface used to steer a ship, boat, submarine, hovercraft, aircraft, or other vehicle that moves through a fluid medium (generally air or water). On an aircraft the rudder is used primarily to counter adve ...

. Juvenile sharptail molas are known to feed on

benthic The benthic zone is the ecological region at the lowest level of a body of water such as an ocean, lake, or stream, including the sediment surface and some sub-surface layers. The name comes from ancient Greek, βένθος (bénthos), meaning " ...

annelid The annelids (Annelida , from Latin ', "little ring"), also known as the segmented worms, are a large phylum, with over 22,000 extant species including ragworms, earthworms, and leeches. The species exist in and have adapted to various ecol ...

s and

sponge Sponges, the members of the phylum Porifera (; meaning 'pore bearer'), are a basal animal clade as a sister of the diploblasts. They are multicellular organisms that have bodies full of pores and channels allowing water to circulate throu ...

s. Adults likely feed on

medusa In Greek mythology, Medusa (; Ancient Greek: Μέδουσα "guardian, protectress"), also called Gorgo, was one of the three monstrous Gorgons, generally described as winged human females with living venomous snakes in place of hair. Those ...

e, siphonophores,

ctenophore Ctenophora (; ctenophore ; ) comprise a phylum of marine invertebrates, commonly known as comb jellies, that inhabit sea waters worldwide. They are notable for the groups of cilia they use for swimming (commonly referred to as "combs"), an ...

s, and salps, as well as some

fish Fish are Aquatic animal, aquatic, craniate, gill-bearing animals that lack Limb (anatomy), limbs with Digit (anatomy), digits. Included in this definition are the living hagfish, lampreys, and Chondrichthyes, cartilaginous and bony fish as we ...

es,

crustacean Crustaceans (Crustacea, ) form a large, diverse arthropod taxon which includes such animals as decapoda, decapods, ostracoda, seed shrimp, branchiopoda, branchiopods, argulidae, fish lice, krill, remipedes, isopoda, isopods, barnacles, copepods, ...

s, and

mollusc Mollusca is the second-largest phylum of invertebrate animals after the Arthropoda, the members of which are known as molluscs or mollusks (). Around 85,000 extant species of molluscs are recognized. The number of fossil species is est ...

s. Sharptail molas sometimes have

remora The remora (), sometimes called suckerfish, is any of a family (Echeneidae) of ray-finned fish in the order Carangiformes. Depending on species, they grow to long. Their distinctive first dorsal fins take the form of a modified oval, sucker-li ...

s attached to the surface of their bodies or inside their buccal cavities. In 1949, a sharptail mola off

North Carolina North Carolina () is a U.S. state, state in the Southeastern United States, Southeastern region of the United States. The state is the List of U.S. states and territories by area, 28th largest and List of states and territories of the United ...

was found with a common remora (''Remora remora'') wedged inside the gill arches on its right side. This evidently impaired the respiration of the mola, such that it foundered on the beach and was collected by fishermen. Molas are

oviparous Oviparous animals are animals that lay their eggs, with little or no other embryonic development within the mother. This is the reproductive method of most fish, amphibians, most reptiles, and all pterosaurs, dinosaurs (including birds), and m ...

and are amongst the most fecund of all fishes.

Larva A larva (; plural larvae ) is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle. ...

l sharptail molas are rounded in shape and develop large pyramidal dermal spines over their bodies, which persist through a prejuvenile phase called the "Molacanthus" stage. In this stage, the body is deep and compressed, with a thin, keel-like structure below the abdominal region. This ridge is made from skin and covered with several rows of small spines. The skin is rough, being covered with small prickles. The spines eventually diminish in size and disappear, leaving scars obvious on the sides of young fish up to long. Their coloration is dark brown on the back, becoming very light on the sides and belly. The lifespan for this species is estimated to be 85 years for males and 105 years for females.

Relationship to humans

Since 2002, promotion of an ocean sunfish festival in

Hualien County Hualien County ( Mandarin Wade–Giles: Hua¹-lien² Hsien⁴; Pīnyīn: ''Huālián Xiàn''; Hokkien POJ: ''Hoa-lian-koān'' or ''Hoa-liân-koān''; Hakka PFS: ''Fâ-lièn-yen''; Amis: ''Kalingko'') is a county on the east coast of Taiwan. I ...

, Taiwan, has increased demand for the meat of the sunfish (called "mambo fish" after a public vote), whereas before only the

intestine The gastrointestinal tract (GI tract, digestive tract, alimentary canal) is the tract or passageway of the digestive system that leads from the mouth to the anus. The GI tract contains all the major organs of the digestive system, in humans an ...

s and reproductive organs were sold while the rest of the fish was discarded. The month-long April festival draws some 120,000 visitors, and features "101 ways to eat" sunfish. Consequently, catches of sunfishes off eastern Taiwan have risen sharply, with the sharptail mola comprising 90% of the catch. In 2005, 208 tonnes were landed and the annual sunfish catch was valued at US$ one million. The species is caught by set net, drift net, and longline fisheries. The impact of this increased exploitation on sunfish stocks is under investigation.

Discovery of a 450-pound Sharptail mola

On Wednesday 30 November 2022, the carcass of a 450-pound Sharptail mola was found ashore on a beach in

. It was kept by the North Carolina Museum of Natural Sciences.

References

{{Taxonbar, from=Q93600 sharptail mola Pantropical fish sharptail mola