The sharptooth houndshark, or spotted gully shark (''Triakis megalopterus'') 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 appropriate s ...

houndshark Houndsharks, the Triakidae, are a family of ground sharks, consisting of about 40 species in nine genera. In some classifications, the family is split into two subfamilies, with '' Mustelus'', '' Scylliogaleus'', and ''Triakis'' in the subfamily ...

in the

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

Triakidae found in shallow inshore waters from southern

Angola , national_anthem = " Angola Avante"() , image_map = , map_caption = , capital = Luanda , religion = , religion_year = 2020 , religion_ref = , coordina ...

South Africa South Africa, officially the Republic of South Africa (RSA), is the Southern Africa, southernmost country in Africa. It is bounded to the south by of coastline that stretch along the Atlantic Ocean, South Atlantic and Indian Oceans; to the ...

. Favoring sandy areas near rocky

reef A reef is a ridge or shoal of rock, coral or similar relatively stable material, lying beneath the surface of a natural body of water. Many reefs result from natural, abiotic processes— deposition of sand, wave erosion planing down rock o ...

s and

gullies A gully is a landform created by running water, mass movement, or commonly a combination of both eroding sharply into soil or other relatively erodible material, typically on a hillside or in river floodplains or terraces. Gullies resemble lar ...

, it is an active-swimming species that usually stays close to the bottom. This robust shark reaches in length and has characteristically large, rounded fins; the

pectoral 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 ...

s in particular are broad and sickle-shaped in adults. It also has a short, blunt snout and long furrows around its mouth. This species is gray or bronze in color above, with variable amounts of black spotting. Mainly active at night, the sharptooth houndshark feeds mostly on

crustacean Crustaceans (Crustacea, ) form a large, diverse arthropod taxon which includes such animals as decapods, seed shrimp, branchiopods, fish lice, krill, remipedes, isopods, barnacles, copepods, amphipods and mantis shrimp. The crustacean group can ...

s, bony fishes, and cephalopods. It has been observed gathering in groups in shallow water during summertime, possibly for reproductive purposes. This species is

aplacental viviparous Ovoviviparity, ovovivipary, ovivipary, or aplacental viviparity is a term used as a "bridging" form of reproduction between egg-laying oviparous and live-bearing viviparous reproduction. Ovoviviparous animals possess embryos that develop ins ...

, meaning that the unborn young are sustained mainly by

yolk Among animals which produce eggs, the yolk (; also known as the vitellus) is the nutrient-bearing portion of the egg whose primary function is to supply food for the development of the embryo. Some types of egg contain no yolk, for example ...

. Females give birth to 6–12 pups between late May and August, on a 2- or 3-year cycle. The sharptooth houndshark is often hooked by recreational anglers, and some are also captured on commercial bottom longlines. Because of its small range and low growth and reproductive rates, it is very vulnerable to overfishing. The

International Union for Conservation of Nature The International Union for Conservation of Nature (IUCN; officially International Union for Conservation of Nature and Natural Resources) is an international organization working in the field of nature conservation and sustainable use of nat ...

has listed this species as least concern.

Taxonomy and phylogeny

Scottish

zoologist Zoology ()The pronunciation of zoology as is usually regarded as nonstandard, though it is not uncommon. is the branch of biology that studies the animal kingdom, including the structure, embryology, evolution, classification, habits, and d ...

Andrew Smith originally described the sharptooth houndshark as a species of ''

Mustelus ''Mustelus'', also known as the smooth-hounds, is a genus of sharks in the family Triakidae. The name of the genus comes from the Latin word ''mustela'', meaning weasel. It should not be confused with the genus name ''Mustela'', which is used ...

'' in 1839, as part of his work ''Illustrations of the Zoology of South Africa''. His account was based on two specimens caught off the Cape of Good Hope,

. Smith named the shark ''megalopterus'', from the

Greek Greek may refer to: Greece Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group. *Greek language, a branch of the Indo-European language family. **Proto-Greek language, the assumed last common ancestor ...

''mega'' ("large") and ''pteron'' ("wing"), referring to its large fins. Another common name for this shark is "sweet William". Later authors have reassigned the sharptooth houndshark to the genus '' Triakis'', more specifically to the subgenus ''Cazon'' alongside the

sharpfin houndshark The sharpfin houndshark (''Triakis acutipinna'') is a houndshark of the family Triakidae. Only two specimens have been found, both in the coastal waters of Ecuador, the longest one being 1.02 m in length. The reproduction of this houndshark is o ...

(''T. acutipinna'') and the spotted houndshark (''T. maculata''). A 2006

phylogenetic In biology, phylogenetics (; from Greek φυλή/ φῦλον [] "tribe, clan, race", and wikt:γενετικός, γενετικός [] "origin, source, birth") is the study of the evolutionary history and relationships among or within groups o ...

study by J. Andrés López and colleagues, based on four

protein Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, res ...

-coding

gene In biology, the word gene (from , ; "... Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''generation'' or ''birth'' or ''gender'') can have several different meanings. The Mendelian gene is a b ...

sequences, found that this species did not group with the

leopard shark The leopard shark (''Triakis semifasciata'') is a species of houndshark, in the family Triakidae. It is found along the Pacific coast of North America, from the U.S. state of Oregon to Mazatlán in Mexico. Typically measuring 1.2–1.5 m (3.9� ...

(''T. semifasciata''). Instead, the

flapnose houndshark The flapnose houndshark (''Scylliogaleus quecketti'') is a houndshark of the family Triakidae, and the only member of the genus ''Scylliogaleus''. It is found in the waters off subtropical South Africa, in the western Indian Ocean between latit ...

(''Scylliogaleus quecketti'') and it formed a clade within the ''Mustelus'' lineage. This result suggests that the two subgenera of ''Triakis''—''Cazon'' and ''Triakis''—may not be closely related, which would warrant a redefinition of the genus.

Description

The sharptooth houndshark is a stout-bodied species with a short, thick, and blunt snout. The nostrils are widely spaced and preceded by lobe-like flaps of skin that do not reach the mouth. The horizontally oval eyes have ridges underneath and are equipped with nictitating membranes. The large mouth bears long, deep furrows at the corners, with those on the lower jaw almost meeting in the middle. The teeth are small and tightly packed to form pavement-like surfaces. Each tooth has a rounded, molar-like base that rises to a sharp, upright central cusp; rarely, a pair of barely developed lateral cusplets may also be present. Five pairs of

gill slit Gill slits are individual openings to gills, i.e., multiple gill arches, which lack a single outer cover. Such gills are characteristic of cartilaginous fish such as sharks and rays, as well as deep-branching vertebrates such as lampreys. In con ...

s are found. The fins are distinctively large and rounded at the tips. The

s of adults are broad and falcate (sickle-shaped). The

dorsal fin A dorsal fin is a fin located on the back of most marine and freshwater vertebrates within various taxa of the animal kingdom. Many species of animals possessing dorsal fins are not particularly closely related to each other, though through c ...

s have nearly vertical trailing margins, with the first originating over the pectoral fin rear tips. The second dorsal fin is about three-quarters as high as the first. The anal fin is much smaller than the second dorsal fin and originates well behind it. The short, thick

caudal peduncle 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 ...

lacks notches at the

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 ...

origins. The caudal fin has a small but well-defined lower lobe and a longer upper lobe with a ventral notch near the tip. The skin is often loose. This species is dark gray to bronze above and white below. Young sharks are mostly unmarked, while adults vary from plain to densely covered with irregular black spots. It may reach in length and in weight. Females grow larger than males.

Distribution and habitat

The range of the sharptooth houndshark is limited to the coastal waters of

southern Africa Southern Africa is the southernmost subregion of the African continent, south of the Congo and Tanzania. The physical location is the large part of Africa to the south of the extensive Congo River basin. Southern Africa is home to a number o ...

, from southern

Angola , national_anthem = " Angola Avante"() , image_map = , map_caption = , capital = Luanda , religion = , religion_year = 2020 , religion_ref = , coordina ...

to the Eastern Cape (or rarely KwaZulu-Natal) in South Africa. This locally common species inhabits sandy

habitat In ecology, the term habitat summarises the array of resources, physical and biotic factors that are present in an area, such as to support the survival and reproduction of a particular species. A species habitat can be seen as the physical ...

s such as bays; it can be found from the

surf zone As ocean surface waves approach shore, they get taller and break, forming the foamy, bubbly surface called ''surf''. The region of breaking waves defines the surf zone, or breaker zone. After breaking in the surf zone, the waves (now reduced i ...

to a depth of , but the majority is found no deeper than . It generally swims just barely above the bottom, favoring flat areas near rocky

s or gullies, and seldom rises into open water.

Biology and ecology

The sharptooth houndshark is a highly active species, though it can sometimes be found resting inside rocky crevices. It mainly hunts at night and has been known to pursue prey almost onto the shore. The pointed cusps of its teeth allow it to grasp slippery prey, while their broad bases allow it to crush hard-shelled prey. This shark feeds on a variety of

s ( crabs,

slipper lobster Slipper lobsters are a family (Scyllaridae) of about 90 species of achelate crustaceans, in the Decapoda clade Reptantia, found in all warm oceans and seas. They are not true lobsters, but are more closely related to spiny lobsters and furry ...

s, and

spiny lobster Spiny lobsters, also known as langustas, langouste, or rock lobsters, are a family (Palinuridae) of about 60 species of achelate crustaceans, in the Decapoda Reptantia. Spiny lobsters are also, especially in Australia, New Zealand, Ireland, So ...

s), bony fishes (including morwongs, sea catfishes, drums, and

porgies The Sparidae are a family of fish in the order Perciformes, commonly called sea breams and porgies. The sheepshead, scup, and red seabream are species in this family. Most sparids are deep-bodied compressed fish with a small mouth separated by a ...

), and cephalopods (in particular ''

Octopus vulgaris The common octopus (''Octopus vulgaris'') is a mollusc belonging to the class Cephalopoda. ''Octopus vulgaris'' is one of the most studied of all octopus species, and also one of the most intelligent. It ranges from the eastern Atlantic, extends ...

''). Sharks and rays (including

catshark Catsharks are ground sharks of the family Scyliorhinidae. They are the largest family of sharks with around 160 species placed in 17 genera. Although they are generally known as catsharks, some species can also be called dogfish due to previous ...

s and

guitarfish The guitarfish, also referred to as shovelnose rays, are a family, Rhinobatidae, of rays. The guitarfish are known for an elongated body with a flattened head and trunk and small, ray-like wings. The combined range of the various species is trop ...

es) and their egg capsules are a minor food source for larger individuals. Off South Africa, the most important prey species is the crab '' Plagusia chabrus''. Its dietary composition changes with age; young sharks under long subsist almost completely on crabs, while larger sharks consume more bony fishes and cephalopods, as well as a greater variety of prey overall. This shark has been observed deviating from its nocturnal habits to feed on chokka squid (''Loligo reynaudii'') during their mass spawnings. The

broadnose sevengill shark The broadnose sevengill shark (''Notorynchus cepedianus'') is the only extant member of the genus ''Notorynchus'', in the family Hexanchidae. It is recognizable because of its seven gill slits, while most shark species have five gill slits, with ...

(''Notorynchus cepedianus'') is known to prey on this species. During the summer, the sharptooth houndshark forms

groups A group is a number of persons or things that are located, gathered, or classed together. Groups of people * Cultural group, a group whose members share the same cultural identity * Ethnic group, a group whose members share the same ethnic ide ...

in shallow water. These aggregations are particularly well-documented in

False Bay False Bay (Afrikaans ''Valsbaai'') is a body of water in the Atlantic Ocean between the mountainous Cape Peninsula and the Hottentots Holland Mountains in the extreme south-west of South Africa. The mouth of the bay faces south and is demarcat ...

and may be related to reproduction, given the presence of many pregnant females. It is

, with the developing embryos nourished mainly by

. Mature females have a single functional ovary and two functional uteri. Litters of 6–12 pups are birthed between late May and August, following a gestation period of some 20 months. Larger females tend to produce larger litters. The length at birth has been variously estimated as and by different sources; pups within a single litter may vary in size by up to 30%. Females apparently reproduce either every two or three years, depending on whether she has ovarian eggs developing during the pregnancy that would allow her to mate again within a few months of giving birth. The sharptooth houndshark is a slow-growing species, with both sexes following a similar growth pattern. Males mature sexually at long and 11–13 years of age, while females mature sexually at long and 15–16 years of age. The maximum lifespan is at least 25 years.

Human interactions

Harmless to humans, the sharptooth houndshark adapts well to captivity and has been displayed in

public aquarium A public aquarium (plural: ''public aquaria'' or ''public Water Zoo'') is the aquatic counterpart of a zoo, which houses living aquatic animal and plant specimens for public viewing. Most public aquariums feature tanks larger than those kept b ...

s. It is frequently caught by recreational anglers from shore or ski-boats; it is edible but rarely eaten. Small numbers are also caught incidentally by a commercial demersal longline fishery targeting the

school shark The school shark (''Galeorhinus galeus'') is a houndshark of the family Triakidae, and the only member of the genus ''Galeorhinus''. Common names also include tope, tope shark, snapper shark, and soupfin shark. It is found worldwide in temperate ...

(''Galeorhinus galeus'') in the

Gansbaai Gansbaai (Dutch/Afrikaans for "bay of geese," sometimes referred to as Gans Bay or Gangs Bay) is a fishing town and popular tourist destination in the Overberg District Municipality, Western Cape, South Africa. It is known for its dense populatio ...

and False Bay region. The meat from sharks caught in the fishery is either made into

biltong Biltong is a form of dried, cured meat that originated in Southern African countries (South Africa, Zimbabwe, Malawi, Namibia, Botswana, and Zambia). Various types of meat are used to produce it, ranging from beef to game meats such as ...

jerky Jerky is lean trimmed meat cut into strips and dried (dehydrated) to prevent spoilage. Normally, this drying includes the addition of salt to prevent bacteria growth before the meat has finished the dehydrating process. The word "jerky" derive ...

and sold locally, or exported fresh or frozen to

Italy Italy ( it, Italia ), officially the Italian Republic, ) or the Republic of Italy, is a country in Southern Europe. It is located in the middle of the Mediterranean Sea, and its territory largely coincides with the homonymous geographical ...

and

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 nort ...

. Although in South Africa, the sharptooth houndshark is listed as a noncommercial species, thus cannot be harvested commercially, it is often mistaken for the common smooth-hound (''Mustelus mustelus'') by fishers. The

has assessed the sharptooth houndshark as least concern. This species is highly susceptible to even moderate levels of fishing pressure, due to its restricted range, slow growth rate, and low

fecundity Fecundity is defined in two ways; in human demography, it is the potential for reproduction of a recorded population as opposed to a sole organism, while in population biology, it is considered similar to fertility, the natural capability to pr ...

. The fact that most sharks caught by fishers are immature is an additional source of concern.

References

External links

''Triakis megalopterus'', Sharptooth houndshark
a
FishBase
{{Taxonbar, from=Q2243090

sharptooth houndshark The sharptooth houndshark, or spotted gully shark (''Triakis megalopterus'') is a species of houndshark in the family Triakidae found in shallow inshore waters from southern Angola to South Africa. Favoring sandy areas near rocky reefs and gullie ...

Fish of Namibia Fish of South Africa Vertebrates of Southern Africa