Dusky smooth-hound

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Dusky smooth-hound
Mustelus canis SI2.jpg
Mustelus canis head SI.jpg
Scientific classification Red Pencil Icon.png
Kingdom: Animalia
Phylum: Chordata
Class: Chondrichthyes
Superorder: Selachimorpha
Order: Carcharhiniformes
Family: Triakidae
Genus: Mustelus
Species:
M. canis
Binomial name
Mustelus canis
(Mitchill, 1815)
Mustelus canis distmap.png
Range of the dusky smooth-hound
Synonyms

Allomycter dissutusGuitart Manday, 1972
Mustelus canis insularisHeemstra, 1997
Squalus canisMitchill, 1815

Contents

The dusky smooth-hound (Mustelus canis), also called the smooth dogfish or the dog shark, is a species of houndshark in the family Triakidae. [1] This shark is an olive grey or brown in color, and may have shades of yellow or grayish white. Females live to 16 years and males have a lifespan of 10 years. M. canis was the first shark recognised to have viral infections. [2]

Taxonomy

M. canis can be known as smooth dogfish, Atlantic smooth dogfish, dusky smooth-hound, grayish, nurse shark, smooth dog, or smooth-hound. It was originally named Squalls canis. [3] In Latin, mustelus translates to weasel and canis translates to dog. M. canis has an allopatric relationship with M. mustelus (common smooth-hound) and a sympatric relationship with M. norrisi (narrowfin smooth-hound). [4]

Distribution and habitat

M. canis is found in marine and brackish waters and is demersal (bottom-dwelling) and oceanodromous (migratory in seas). They can be found between 42°N and 44°S and 100 and 46°W. [5] M. canis in the North Atlantic migrates in response to changing temperature. In winter, they can be found in the Carolinas to the outlet of the Chesapeake Bay, and in summer from the mid-Atlantic to southern New England. [6] They are most abundant on the East Coast, from Massachusetts to Florida, Brazil to Argentina, and in the Gulf of Mexico. [3] They are mostly found in waters shallower than 60 ft (18 m), but can be found to 665 ft (200 m) deep. [3]

Anatomy and appearance

Smooth dogfish are relatively small and slender. They have elongated, oval-shaped eyes with a spiracle located directly behind on each side. They have triangular fins. [3] Their first and second dorsal fins are well-serrated and nearly equal in size. [5] The second dorsal fin is slightly smaller than the first and twice as large as the anal fin. The caudal fin has two asymmetrical lobes, the lower is smaller and rounder and the upper has a deep notch. [5] They do not have any fin spines, unlike the spiny dogfish. They have a tapering, blunt snout. They can be gray to brown and their undersides can be white to yellowish gray. Smooth dogfish have the ability to change colors using melanophores to help them camouflage. [3] Newborns have lighter gray edges on their fins and have tail fins edged in white. On average, smooth dogfish are about 48 in long, but can reach up to 5 ft. [3] They have an inter-dorsal ridge. [7]

Dentition

One main characteristic of elasmobranch fishes is their ability to continually replace the teeth in their upper and lower jaws. [8] Smooth dogfish differ from other sharks because of their 10 rows of flat, blunt teeth. [8] The teeth in the upper and lower jaws are similar in size and are asymmetrical with rounded cusps. These teeth are used to crush and grind food, rather than bite it. [8] Their unique dentition is important for their crustacean-based diet. [8]

In smooth dogfish, tooth replacement is related to body growth. They grow about 10 cm per every six rows of teeth replaced. That is an increase of 0.03 mm per replaced tooth. Teeth are replaced at a rate of one row per 10 to 12 days. [8]

Diet

M. canis feeds mostly on crustaceans, polychaetes, and mollusks. [9] Smooth dogfish also eat squid, worms, small fish, razor clams, and occasionally garbage. [10] They are nocturnal scavengers and opportunistic predators. [3] Their nocturnal activity helps them to take advantage of concentrations of crustacean prey. [9]

Reproduction

The mating season of smooth dogfish is from May to June. They are viviparous and have a yolk-sac placenta. Females can store sperm up to a year, but how long it can be used is not known. [3] Their gestation period is 10 to 11 months and litters can be between four and 20 pups. The pups are 13 to 15 in (34 to 39 cm) long when born. [5] Males reach sexual maturity between 2 and 3 years or 68 and 93 cm in length. Females reach sexual maturity between 4 and 5 years or 70 and 130 cm in length. [5] Smooth dogfish have a relatively low population doubling time of 4.5 to 14 years. [5] Because of their late maturation, low fecundity, and restricted distributions, they are still more vulnerable to overfishing than teleost fishes. [11]

Juvenile females have filiform uteri, small ovaries with undifferentiated oocyctes, egg cells, and narrow, thread-like oviducts with undeveloped oviducal glands. Adolescents have enlarged oviducal glands with distinguishable oocytes and no or few corpora lutea. Adults have large ovaries and vitellogenic oocytes. Spermatozoa has been observed in preovulatory females. [11]

Juvenile males have soft, small claspers and undeveloped testes with straight, thread-like ampullae ductus deferens. Adolescents' testes have increased weight and claspers are extended and calcified, but are still flexible. Adults have fully formed and calcified claspers and large and developed testes. [11]

Relationship to humans

Commercial fisheries have had an increased interest in smooth dogfish since the 1900s. [6] They are caught using longlines and bottom trawls primarily off of Massachusetts, New Jersey, Maryland, Virginia, and North Carolina. [3] Mostly, they are considered bycatch when fishing for other species, which has put them in the near-threatened category by the IUCN Red List of Threatened Species. [5] They are no danger to humans because of their blunt teeth. [3]

Tonic immobility

Tonic immobility has been reported in several cartilaginous fishes, one of which is M. canis. [12] Tonic immobility is induced by grasping the first dorsal fin with one hand and the body immediately anterior to the anal fin with the other, inverting the shark and holding it rigidly. The mean time to induce tonic immobility in smooth dogfish was 32.5 seconds. The mean duration of the tonic immobility was 61.9 seconds. Sharks that had the "limp" response also exhibited tonic immobility. The "limp" response is a criterion for the onset of tonic immobility. [12]

Related Research Articles

Squalidae, more commonly known as dogfish, dog sharks, or spiny dogfish, are one of several families of sharks categorized under Squaliformes, making it the second largest order of sharks, numbering 119 species across 7 families. Having earned their name after a group of fishermen reportedly observed the species chasing down smaller fish in dog-like packs, dogfish have slender, streamlined bodies, usually more compact in comparison to other species, and a pointed snout. Dogfish likewise have two dorsal fins, each with smooth spines, but no anal fin, and their skin is generally rough to the touch. As the species reaches adulthood, males usually measure a maximum of 39 inches, while females typically measure 49 inches long. The species therefore exhibits female-dominant sexual dimorphism.

Smooth-hound Genus of sharks

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 for weasels.

Houndshark Family of sharks

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 Triakinae, and the remaining genera in the subfamily Galeorhininae.

Dusky shark Species of shark

The dusky shark is a species of requiem shark, in the family Carcharhinidae, occurring in tropical and warm-temperate continental seas worldwide. A generalist apex predator, the dusky shark can be found from the coast to the outer continental shelf and adjacent pelagic waters, and has been recorded from a depth of 400 m (1,300 ft). Populations migrate seasonally towards the poles in the summer and towards the equator in the winter, traveling hundreds to thousands of kilometers. One of the largest members of its genus, the dusky shark reaches 4.2 m (14 ft) in length and 347 kg (765 lb) in weight. It has a slender, streamlined body and can be identified by its short round snout, long sickle-shaped pectoral fins, ridge between the first and second dorsal fins, and faintly marked fins.

Gummy shark Species of shark

The gummy shark, also known as the Australian smooth hound, flake, sweet william or smooth dog-shark, is a shark in the family Triakidae. These small to medium-sized bottom-dwelling sharks are found mostly in, but are not limited to, the area around the southern seas of Australia and is commonly baited and fished for cuisine because of its taste and market prices. According to a 2021 paper by White, Arunrugstichai & Naylorn (2021), Mustelus walkeri is the same animal as M. antarcticus. One theory is that M. walkeri is a subpopulation of M. antarcticus.

Slender smooth-hound Species of shark

The slender smooth-hound or gollumshark is a species of ground shark in the family Pseudotriakidae. It is endemic to the waters around New Zealand, where it is usually found close to the bottom over the continental slope at depths of 300–600 m (980–1,970 ft). An extremely slim, plain brownish shark reaching 1.1 m (3.6 ft) in length, the slender smooth-hound can be identified by its broad, flattened head with a long, distinctively bell-shaped snout. Its mouth is angular with short furrows at the corners, and contains a very high number of tooth rows in both jaws. Its two dorsal fins are roughly equal in size.

Common smooth-hound Species of shark

The common smooth-hound is a houndshark of the family Triakidae. It is found in the eastern Atlantic Ocean from the British Isles to South Africa, and in the Mediterranean Sea, Madeira, and the Canary Islands at depths ranging from 5 m to 625 m. While they can grow to 200 cm, their usual maximum size is 150 cm. They commonly grow to 100–120 cm with a birth length around 35 cm. The reproduction of commons smooth-hounds is viviparous.

Viper dogfish Species of shark

The viper dogfish or viper shark is a rare species of dogfish shark in the family Etmopteridae, and the only extant member of its genus. It has been found in the Pacific Ocean off southern Japan, the Bonin Islands, Pacific Ocean off northern Taitung County and the Northwestern Hawaiian Islands. This species inhabits upper continental slopes and seamounts. It may migrate vertically, shifting between bottom waters 270–360 m (890–1,180 ft) deep during the day and upper waters less than 150 m (490 ft) deep at night. A slender, black shark reaching 54 cm (21 in) in length, the viper dogfish can be recognized by its narrow, triangular jaws and well-spaced, fang-like teeth. It also has two spined dorsal fins, dermal denticles with faceted crowns, and numerous light-emitting photophores concentrated on its ventral surface.

Spotted houndshark Species of shark

The spotted houndshark, Triakis maculata, is a houndshark of the family Triakidae found in tropical waters in the eastern Pacific Ocean off the coast of South America. It usually grows to a length around 180 centimetres (71 in). The reproduction of this houndshark is ovoviviparous, with a litter of 14 pups being found in one female with a birth size of 30 to 40 centimetres. Their diet is believed to consist mainly of crustaceans.

Sharptooth houndshark Species of shark

The sharptooth houndshark, or spotted gully shark 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 gullies, it is an active-swimming species that usually stays close to the bottom. This robust shark reaches 1.7 m (5.6 ft) in length and has characteristically large, rounded fins; the pectoral fins 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.

Banded houndshark Species of shark

The banded houndshark is a species of houndshark in the family Triakidae, common in the northwestern Pacific Ocean from the southern Russian Far East to Taiwan. Found on or near the bottom, it favors shallow coastal habitats with sandy or vegetated bottoms, and also enters brackish water. This shark reaches 1.5 m (4.9 ft) in length. It has a short, rounded snout and mostly narrow fins; the pectoral fins are broad and triangular, and the trailing margin of the first dorsal fin is almost vertical. It is gray above and lighter below; younger sharks have darker saddles and dots, which fade with age.

Starry smooth-hound Species of shark

The starry smooth-hound is a houndshark of the family Triakidae. It is found on the continental shelves of the northeast Atlantic, between latitudes 61° N and 16° N, from the surface to a depth of 200 m (660 ft). It can grow up to a length of 1.4 m.

Spotless smooth-hound Species of shark

The spotless smooth-hound is a species of houndshark, in the family Triakidae, found on the continental shelves of the northwest Pacific, between latitudes 40° N and 11° N, from the surface to a depth of 300 m. It can grow to a length of up to 1 m.

Brown smooth-hound Species of shark

The brown smooth-hound is a houndshark of the family Triakidae. It is found on the continental shelves of the subtropical eastern Pacific, from northern California to the Gulf of California, as well as Ecuador and Peru between latitudes 43° N and 18° S, from the surface to a depth of 200 m. It can grow up to a length of 1 m. The reproduction of this shark is viviparous.

Sicklefin smooth-hound Species of shark

The sicklefin smooth-hound is a houndshark of the family Triakidae. Even some species look similar to Carcharhinus family, mustelus second dorsal fin is much bigger. It is found on the continental shelves of the eastern Pacific, between latitudes 33° N and 7° N. The difference between sharptooth smooth-hound and mustelus lunulatus, is that the lunulatus second dorsal fin origin far in advance of the anal fin. It can reach a length of up to 1.7 m. The reproduction of this shark is ovoviviparous.

Speckled smooth-hound Species of shark

The speckled smooth-hound is a houndshark of the family Triakidae. It is found on the continental shelf of the eastern Pacific, between latitudes 0° and 54° S, at depths between 16 and 50 m. It can reach a length of 130 cm (51 in). Collectively with certain other species of shark, it is known as "tollo".

Gulf smooth-hound Species of shark

The Gulf smooth-hound is a houndshark of the family Triakidae, found on the continental shelves of the tropical western central Atlantic. The reproduction of this houndshark is placental viviparous.

Humpback smooth-hound Species of shark

The humpback smooth-hound is a houndshark of the family Triakidae. It is found on the continental shelves of the tropical southeast Pacific, from Peru to southern Chile, between latitudes 3° S and 54° S, at depths between 15 and 210 metres.

Australian grey smooth-hound Species of shark

The Australian grey smooth-hound or also known as the grey gummy shark is a species of houndshark classified under the large family Triakidae. It is one of the twenty-eight species belonging to the genus Mustelus, which are often small in length. While members of the genus Mustelus may be found globally in tropical and temperate waters, the grey gummy shark in particular is native to the Pacific Ocean and Indian Ocean waters surrounding Australia and is particularly widespread in deep coastal waters. The grey gummy shark is known to be a viviparous species and gives birth to live young. With little data available, it is regarded to have a relatively stable population and possesses little threat to humans.

References

  1. 1 2 Carlson, J.; Charvet, P.; Blanco-Parra, MP, Briones Bell-lloch, A.; Cardenosa, D.; Derrick, D.; Espinoza, E.; Morales-Saldaña, J.M.; Naranjo-Elizondo, B.; Pacoureau, N.; Pérez Jiménez, J.C.; Schneider, E.V.C.; Simpson, N.J.; Talwar, B.S.; Pollom, R. (2021). "Mustelus canis". IUCN Red List of Threatened Species . 2021: e.T39359A2908200. doi: 10.2305/IUCN.UK.2021-1.RLTS.T39359A2908200.en . Retrieved 18 November 2021.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  2. ↑ Leibovitz, L. & Lebouitz, S. S. (1985). "A viral dermatitis of the smooth dogfish, Mustelus canis (Mitchill)". Journal of Fish Diseases . 8 (3): 273–279. doi:10.1111/j.1365-2761.1985.tb00943.x.
  3. 1 2 3 4 5 6 7 8 9 10 "Mustelus canis :: Florida Museum of Natural History". www.flmnh.ufl.edu. Retrieved 2016-03-14.
  4. ↑ "Mustelus canis summary page". FishBase. Retrieved 2016-03-14.
  5. 1 2 3 4 5 6 7 "Smooth Dogfishes, Mustelus canis". MarineBio.org. Archived from the original on 2016-10-10. Retrieved 2016-03-14.
  6. 1 2 Conrath, C.L.; Musick, J.A. (2002). "Reproductive biology of the smooth dogfish, Mustelus canis, in the northwest Atlantic Ocean" (PDF). Environmental Biology of Fishes. 64 (4): 367–377. doi:10.1023/A:1016117415855. S2CID   24065134.
  7. ↑ "SMOOTH DOGFISH (Mustelus canis)". nefsc.noaa.gov. Archived from the original on 2016-03-16. Retrieved 2016-04-04.
  8. 1 2 3 4 5 Moss, S. A. (1972). "Tooth Replacement and Body Growth Rates in the Smooth Dogfish, Mustelus canis (Mitchell)". Copeia. 1972 (4): 808–811. doi:10.2307/1442738. JSTOR   1442738.
  9. 1 2 Rountree, R. A.; Able, K. W. (1996). "Seasonal abundance, growth, and foraging habits of juvenile smooth dogfish, Mustelus canis, in a New Jersey estuary" (PDF). Fishery Bulletin. 94 (3): 522–534.
  10. ↑ "Dusky smoothhound photo – Mustelus canis – G97295". ARKive. Archived from the original on 2016-08-22. Retrieved 2016-04-04.
  11. 1 2 3 Zagaglia, C. R.; Damiano, C.; Hazin, F. V.; Broadhurst, M. K. (2011). "Reproduction in Mustelus canis (Chondrichthyes: Triakidae) from an unexploited population off northern Brazil". Journal of Applied Ichthyology. 27 (1): 25–29. doi:10.1111/j.1439-0426.2010.01573.x.
  12. 1 2 Whitman, P. A.; Marshall, J.A.; Keller, E. C. (1986). "Tonic immobility in the smooth dogfish shark, Mutelus canis (Pisces, Carcharhinidae)". Copeia. 1986 (3): 829–832. doi:10.2307/1444973. JSTOR   1444973.
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