Banded houndshark
Encyclopedia
The banded houndshark (Triakis scyllium) is a species
of houndshark, 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 habitat
s 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.
Nocturnal and largely solitary, the banded houndshark preys on benthic invertebrate
s and bony fishes. It is aplacental viviparous, with the developing embryo
s sustained by yolk. After mating
during summer, females bear as many as 42 pups following a gestation period
of 9–12 months. The banded houndshark poses no danger to humans and adapts well to captivity. It is caught as bycatch
off Japan
, Taiwan
, and likely elsewhere in its range; it may be eaten but is not as well-regarded as related species. Because fishing does not appear to have diminished this shark's population, the International Union for Conservation of Nature (IUCN) has listed it under Least Concern
.
and Friedrich Gustav Jakob Henle
, based on a dried specimen from Japan
, in their 1838–41 Systematische Beschreibung der Plagiostomen. They gave it the specific epithet scyllium, derived from the Ancient Greek
skylion ("dogfish"), and placed it in the genus Triakis. Within the genus, it is placed in the subgenus Triakis along with the leopard shark
(T. (Triakis) semifasciata).
, the banded houndshark occurs from the southern Russian Far East
to Taiwan
, including Japan, Korea
, and eastern China
; records from the Philippines
are questionable. This common, benthic shark is found over continental and insular shelves
, mostly close to shore but also to a depth of 150 m (492.1 ft). It frequents sandy flats and beds of seaweed
and eelgrass
; additionally it is tolerant of brackish water
and enters estuaries and bay
s.
s (protective third eyelids) and have prominent ridges underneath. The mouth forms a short, wide arch and bears long furrows at the corners that extend onto both jaws. Each tooth has an upright to oblique knife-like central cusp flanked by strong cusplets. There are five pairs of gill slit
s.
Most of the fins are fairly narrow; in adults the pectoral fins are broad and roughly triangular. The moderately tall first dorsal fin
is placed about halfway between the pectoral and pelvic fins, and its trailing margin is nearly vertical near the apex. The second dorsal fin
is about three-quarters as high as the first and larger than the anal fin. The caudal fin has a well-developed lower lobe and a prominent ventral notch near the tip of the upper lobe; in young sharks the lower caudal fin lobe is much less distinct. This species is gray above, with darker saddles and scattered black spots that fade with age; the underside is off-white.
s (including shrimp
s, crab
s, hermit crab
s, and mantis shrimp
s), cephalopod
s (including octopus
), and spoon worms
; polychaete worms, tunicate
s, peanut worms, and small, bottom-living bony fishes (including flatfish
es, conger eel
s, herring
, jacks
, drums
, and grunts
) are occasionally consumed. Shrimp and spoon worms are important prey for sharks up to 70 cm (27.6 in) long; cephalopods predominate in the diets of larger sharks.
Mating
occurs during the summer, and involves the male swimming parallel to the female and gripping her pectoral fin with his teeth; thus secured, he then twists the aft portion of his body to insert a single clasper into her cloaca
for copulation. The banded houndshark is aplacental viviparous, in which the developing embryo
s are sustained to birth by yolk. Females bear litters of 9–26 pups after a gestation period
of 9–12 months, though litters as large as 42 pups have been recorded. The newborns measure 18–20 cm (7.1–7.9 in) long. Males mature sexually at 5–6 years old, when they are 93–106 cm (36.6–41.7 in) long, and live up to 15 years. Females mature sexually at 6–7 years old, when they are 106 centimetre long, and live up to 18 years. Known parasites of this species include the tapeworms Callitetrarhynchus gracilis, Onchobothrium triacis, and Phyllobothrium serratum, the leech
Stibarobdella macrothela, and the copepod
s Achtheinus impenderus, Caligus punctatus, Kroyeria triakos, and Pseudopandarus scyllii.
s in China and Japan, and has reproduced in captivity. Individuals have survived in captivity for over five years. This species is often caught incidentally
off Japan in gillnet
s and set nets
; the meat is sometimes sold, but is considered to be of poorer quality than that of other houndsharks in the region. It is caught in lesser numbers off Taiwan
, and is probably also fished off Korea and northern China. The International Union for Conservation of Nature (IUCN) has listed the banded houndshark under Least Concern
, as it remains abundant throughout its range. Off Japan, it can be found in rocky areas that provide refuge from fishing pressure.
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
of houndshark, family
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
Triakidae, common in the northwestern Pacific Ocean
Pacific Ocean
The Pacific Ocean is the largest of the Earth's oceanic divisions. It extends from the Arctic in the north to the Southern Ocean in the south, bounded by Asia and Australia in the west, and the Americas in the east.At 165.2 million square kilometres in area, this largest division of the World...
from the southern Russian Far East
Russian Far East
Russian Far East is a term that refers to the Russian part of the Far East, i.e., extreme east parts of Russia, between Lake Baikal in Eastern Siberia and the Pacific Ocean...
to Taiwan
Taiwan
Taiwan , also known, especially in the past, as Formosa , is the largest island of the same-named island group of East Asia in the western Pacific Ocean and located off the southeastern coast of mainland China. The island forms over 99% of the current territory of the Republic of China following...
. Found on or near the bottom, it favors shallow coastal habitat
Habitat
* Habitat , a place where a species lives and grows*Human habitat, a place where humans live, work or play** Space habitat, a space station intended as a permanent settlement...
s with sandy or vegetated bottoms, and also enters brackish water
Brackish water
Brackish water is water that has more salinity than fresh water, but not as much as seawater. It may result from mixing of seawater with fresh water, as in estuaries, or it may occur in brackish fossil aquifers. The word comes from the Middle Dutch root "brak," meaning "salty"...
. 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
Dorsal fin
A dorsal fin is a fin located on the backs of various unrelated marine and freshwater vertebrates, including most fishes, marine mammals , and the ichthyosaurs...
is almost vertical. It is gray above and lighter below; younger sharks have darker saddles and dots, which fade with age.
Nocturnal and largely solitary, the banded houndshark preys on benthic invertebrate
Invertebrate
An invertebrate is an animal without a backbone. The group includes 97% of all animal species – all animals except those in the chordate subphylum Vertebrata .Invertebrates form a paraphyletic group...
s and bony fishes. It is aplacental viviparous, with the developing embryo
Embryo
An embryo is a multicellular diploid eukaryote in its earliest stage of development, from the time of first cell division until birth, hatching, or germination...
s sustained by yolk. After mating
Mating
In biology, mating is the pairing of opposite-sex or hermaphroditic organisms for copulation. In social animals, it also includes the raising of their offspring. Copulation is the union of the sex organs of two sexually reproducing animals for insemination and subsequent internal fertilization...
during summer, females bear as many as 42 pups following a gestation period
Gestation period
For mammals the gestation period is the time in which a fetus develops, beginning with fertilization and ending at birth. The duration of this period varies between species.-Duration:...
of 9–12 months. The banded houndshark poses no danger to humans and adapts well to captivity. It is caught as bycatch
Bycatch
The term “bycatch” is usually used for fish caught unintentionally in a fishery while intending to catch other fish. It may however also indicate untargeted catch in other forms of animal harvesting or collecting...
off Japan
Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...
, Taiwan
Taiwan
Taiwan , also known, especially in the past, as Formosa , is the largest island of the same-named island group of East Asia in the western Pacific Ocean and located off the southeastern coast of mainland China. The island forms over 99% of the current territory of the Republic of China following...
, and likely elsewhere in its range; it may be eaten but is not as well-regarded as related species. Because fishing does not appear to have diminished this shark's population, the International Union for Conservation of Nature (IUCN) has listed it under Least Concern
Least Concern
Least Concern is an IUCN category assigned to extant taxon or lower taxa which have been evaluated but do not qualify for any other category. As such they do not qualify as threatened, Near Threatened, or Conservation Dependent...
.
Taxonomy
The first scientific description of the banded houndshark was authored by German biologists Johannes Peter MüllerJohannes Peter Müller
Johannes Peter Müller , was a German physiologist, comparative anatomist, and ichthyologist not only known for his discoveries but also for his ability to synthesize knowledge.-Early years and education:...
and Friedrich Gustav Jakob Henle
Friedrich Gustav Jakob Henle
Friedrich Gustav Jakob Henle was a German physician, pathologist and anatomist. He is credited with the discovery of the loop of Henle in the kidney. His essay "On Miasma and Contagia" was an early argument for the germ theory of disease...
, based on a dried specimen from Japan
Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...
, in their 1838–41 Systematische Beschreibung der Plagiostomen. They gave it the specific epithet scyllium, derived from the Ancient Greek
Ancient Greek
Ancient Greek is the stage of the Greek language in the periods spanning the times c. 9th–6th centuries BC, , c. 5th–4th centuries BC , and the c. 3rd century BC – 6th century AD of ancient Greece and the ancient world; being predated in the 2nd millennium BC by Mycenaean Greek...
skylion ("dogfish"), and placed it in the genus Triakis. Within the genus, it is placed in the subgenus Triakis along with the leopard shark
Leopard shark
The leopard shark is a species of houndshark, family Triakidae, found along the Pacific coast of North America from the U.S. state of Oregon to Mazatlán in Mexico...
(T. (Triakis) semifasciata).
Distribution and habitat
Native to the northwestern Pacific OceanPacific Ocean
The Pacific Ocean is the largest of the Earth's oceanic divisions. It extends from the Arctic in the north to the Southern Ocean in the south, bounded by Asia and Australia in the west, and the Americas in the east.At 165.2 million square kilometres in area, this largest division of the World...
, the banded houndshark occurs from the southern Russian Far East
Russian Far East
Russian Far East is a term that refers to the Russian part of the Far East, i.e., extreme east parts of Russia, between Lake Baikal in Eastern Siberia and the Pacific Ocean...
to Taiwan
Taiwan
Taiwan , also known, especially in the past, as Formosa , is the largest island of the same-named island group of East Asia in the western Pacific Ocean and located off the southeastern coast of mainland China. The island forms over 99% of the current territory of the Republic of China following...
, including Japan, Korea
Korea
Korea ) is an East Asian geographic region that is currently divided into two separate sovereign states — North Korea and South Korea. Located on the Korean Peninsula, Korea is bordered by the People's Republic of China to the northwest, Russia to the northeast, and is separated from Japan to the...
, and eastern China
China
Chinese civilization may refer to:* China for more general discussion of the country.* Chinese culture* Greater China, the transnational community of ethnic Chinese.* History of China* Sinosphere, the area historically affected by Chinese culture...
; records from the Philippines
Philippines
The Philippines , officially known as the Republic of the Philippines , is a country in Southeast Asia in the western Pacific Ocean. To its north across the Luzon Strait lies Taiwan. West across the South China Sea sits Vietnam...
are questionable. This common, benthic shark is found over continental and insular shelves
Continental shelf
The continental shelf is the extended perimeter of each continent and associated coastal plain. Much of the shelf was exposed during glacial periods, but is now submerged under relatively shallow seas and gulfs, and was similarly submerged during other interglacial periods. The continental margin,...
, mostly close to shore but also to a depth of 150 m (492.1 ft). It frequents sandy flats and beds of seaweed
Seaweed
Seaweed is a loose, colloquial term encompassing macroscopic, multicellular, benthic marine algae. The term includes some members of the red, brown and green algae...
and eelgrass
Zostera
Zostera is a small genus of widely distributed seagrass, commonly called marine eelgrass or simply eelgrass . The genus Zostera contains sixteen species.-Ecology:Zostera is found on sandy substrates or in estuaries submerged or partially floating...
; additionally it is tolerant of brackish water
Brackish water
Brackish water is water that has more salinity than fresh water, but not as much as seawater. It may result from mixing of seawater with fresh water, as in estuaries, or it may occur in brackish fossil aquifers. The word comes from the Middle Dutch root "brak," meaning "salty"...
and enters estuaries and bay
Bay
A bay is an area of water mostly surrounded by land. Bays generally have calmer waters than the surrounding sea, due to the surrounding land blocking some waves and often reducing winds. Bays also exist as an inlet in a lake or pond. A large bay may be called a gulf, a sea, a sound, or a bight...
s.
Description
The banded houndshark is a moderately slender-bodied species growing up to 1.5 m (4.9 ft) long. The snout is short, broad, and rounded; the widely separated nostrils are each preceded by a lobe of skin that does not reach the mouth. The horizontally oval eyes are placed high on the head; they are equipped with rudimentary nictitating membraneNictitating membrane
The nictitating membrane is a transparent or translucent third eyelid present in some animals that can be drawn across the eye for protection and to moisten it while maintaining visibility. Some reptiles, birds, and sharks have a full nictitating membrane; in many mammals, there is a small...
s (protective third eyelids) and have prominent ridges underneath. The mouth forms a short, wide arch and bears long furrows at the corners that extend onto both jaws. Each tooth has an upright to oblique knife-like central cusp flanked by strong cusplets. There are five pairs of gill slit
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, rays, sawfish, and guitarfish. Most of these have five pairs, but a few species have 6 or 7 pairs...
s.
Most of the fins are fairly narrow; in adults the pectoral fins are broad and roughly triangular. The moderately tall first dorsal fin
Dorsal fin
A dorsal fin is a fin located on the backs of various unrelated marine and freshwater vertebrates, including most fishes, marine mammals , and the ichthyosaurs...
is placed about halfway between the pectoral and pelvic fins, and its trailing margin is nearly vertical near the apex. The second dorsal fin
Dorsal fin
A dorsal fin is a fin located on the backs of various unrelated marine and freshwater vertebrates, including most fishes, marine mammals , and the ichthyosaurs...
is about three-quarters as high as the first and larger than the anal fin. The caudal fin has a well-developed lower lobe and a prominent ventral notch near the tip of the upper lobe; in young sharks the lower caudal fin lobe is much less distinct. This species is gray above, with darker saddles and scattered black spots that fade with age; the underside is off-white.
Biology and ecology
The banded houndshark is nocturnal and generally solitary, though several individuals may rest together, sometimes piled atop one another inside a cave. It feeds mainly on crustaceanCrustacean
Crustaceans form a very large group of arthropods, usually treated as a subphylum, which includes such familiar animals as crabs, lobsters, crayfish, shrimp, krill and barnacles. The 50,000 described species range in size from Stygotantulus stocki at , to the Japanese spider crab with a leg span...
s (including shrimp
Shrimp
Shrimp are swimming, decapod crustaceans classified in the infraorder Caridea, found widely around the world in both fresh and salt water. Adult shrimp are filter feeding benthic animals living close to the bottom. They can live in schools and can swim rapidly backwards. Shrimp are an important...
s, crab
Crab
True crabs are decapod crustaceans of the infraorder Brachyura, which typically have a very short projecting "tail" , or where the reduced abdomen is entirely hidden under the thorax...
s, hermit crab
Hermit crab
Hermit crabs are decapod crustaceans of the superfamily Paguroidea. Most of the 1100 species possess an asymmetrical abdomen which is concealed in an empty gastropod shell that is carried around by the hermit crab.-Description:...
s, and mantis shrimp
Mantis shrimp
Mantis shrimp or stomatopods are marine crustaceans, the members of the order Stomatopoda. They are neither shrimp nor mantids, but receive their name purely from the physical resemblance to both the terrestrial praying mantis and the shrimp. They may reach in length, although exceptional cases of...
s), cephalopod
Cephalopod
A cephalopod is any member of the molluscan class Cephalopoda . These exclusively marine animals are characterized by bilateral body symmetry, a prominent head, and a set of arms or tentacles modified from the primitive molluscan foot...
s (including octopus
Octopus
The octopus is a cephalopod mollusc of the order Octopoda. Octopuses have two eyes and four pairs of arms, and like other cephalopods they are bilaterally symmetric. An octopus has a hard beak, with its mouth at the center point of the arms...
), and spoon worms
Echiura
The Echiura, or spoon worms, are a small group of marine animals. They are often considered to be a group of annelids, although they lack the segmented structure found in other members of that group, and so may also be treated as a separate phylum...
; polychaete worms, tunicate
Tunicate
Tunicates, also known as urochordates, are members of the subphylum Tunicata, previously known as Urochordata, a group of underwater saclike filter feeders with incurrent and excurrent siphons that is classified within the phylum Chordata. While most tunicates live on the ocean floor, others such...
s, peanut worms, and small, bottom-living bony fishes (including flatfish
Flatfish
The flatfish are an order of ray-finned fish, also called the Heterosomata, sometimes classified as a suborder of Perciformes. In many species, both eyes lie on one side of the head, one or the other migrating through and around the head during development...
es, conger eel
Congridae
Congridae is the family of conger and garden eels. Congers are valuable and often large food fishes, while garden eels live in colonies, all protruding from the sea floor after the manner of plants in a garden...
s, herring
Herring
Herring is an oily fish of the genus Clupea, found in the shallow, temperate waters of the North Pacific and the North Atlantic oceans, including the Baltic Sea. Three species of Clupea are recognized. The main taxa, the Atlantic herring and the Pacific herring may each be divided into subspecies...
, jacks
Carangidae
Carangidae is a family of fish which includes the jacks, pompanos, jack mackerels, and scads.They are marine fish found in the Atlantic, Indian and Pacific Oceans...
, drums
Sciaenidae
Sciaenidae is a family of fish commonly called drums, croakers, or hardheads for the repetitive throbbing or drumming sounds they make...
, and grunts
Haemulidae
The grunts are a family, Haemulidae, of fishes in the order Perciformes. They are numerous and widespread, with about 150 species in 19 genera, found in tropical fresh, brackish and salt waters around the world...
) are occasionally consumed. Shrimp and spoon worms are important prey for sharks up to 70 cm (27.6 in) long; cephalopods predominate in the diets of larger sharks.
Mating
Mating
In biology, mating is the pairing of opposite-sex or hermaphroditic organisms for copulation. In social animals, it also includes the raising of their offspring. Copulation is the union of the sex organs of two sexually reproducing animals for insemination and subsequent internal fertilization...
occurs during the summer, and involves the male swimming parallel to the female and gripping her pectoral fin with his teeth; thus secured, he then twists the aft portion of his body to insert a single clasper into her cloaca
Cloaca
In zoological anatomy, a cloaca is the posterior opening that serves as the only such opening for the intestinal, reproductive, and urinary tracts of certain animal species...
for copulation. The banded houndshark is aplacental viviparous, in which the developing embryo
Embryo
An embryo is a multicellular diploid eukaryote in its earliest stage of development, from the time of first cell division until birth, hatching, or germination...
s are sustained to birth by yolk. Females bear litters of 9–26 pups after a gestation period
Gestation period
For mammals the gestation period is the time in which a fetus develops, beginning with fertilization and ending at birth. The duration of this period varies between species.-Duration:...
of 9–12 months, though litters as large as 42 pups have been recorded. The newborns measure 18–20 cm (7.1–7.9 in) long. Males mature sexually at 5–6 years old, when they are 93–106 cm (36.6–41.7 in) long, and live up to 15 years. Females mature sexually at 6–7 years old, when they are 106 centimetre long, and live up to 18 years. Known parasites of this species include the tapeworms Callitetrarhynchus gracilis, Onchobothrium triacis, and Phyllobothrium serratum, the leech
Leech
Leeches are segmented worms that belong to the phylum Annelida and comprise the subclass Hirudinea. Like other oligochaetes such as earthworms, leeches share a clitellum and are hermaphrodites. Nevertheless, they differ from other oligochaetes in significant ways...
Stibarobdella macrothela, and the copepod
Copepod
Copepods are a group of small crustaceans found in the sea and nearly every freshwater habitat. Some species are planktonic , some are benthic , and some continental species may live in limno-terrestrial habitats and other wet terrestrial places, such as swamps, under leaf fall in wet forests,...
s Achtheinus impenderus, Caligus punctatus, Kroyeria triakos, and Pseudopandarus scyllii.
Human interactions
Harmless to humans, the banded houndshark is commonly displayed in public aquariumPublic aquarium
A public aquarium is the aquatic counterpart of a zoo, housing living aquatic species for viewing. Most public aquariums feature tanks larger than those kept by home aquarists, as well as smaller tanks. Since the first public aquariums were built in the mid-19th century, they have become popular...
s in China and Japan, and has reproduced in captivity. Individuals have survived in captivity for over five years. This species is often caught incidentally
Bycatch
The term “bycatch” is usually used for fish caught unintentionally in a fishery while intending to catch other fish. It may however also indicate untargeted catch in other forms of animal harvesting or collecting...
off Japan in gillnet
Gillnet
Gillnetting is a common fishing method used by commercial and artisanal fishermen of all the oceans and in some freshwater and estuary areas. The gillnet also is used by fisheries scientists to monitor fish populations. Because gillnets can be so effective their use is closely monitored and...
s and set nets
Fishing net
A fishing net or fishnet is a net that is used for fishing. Fishing nets are meshes usually formed by knotting a relatively thin thread. Modern nets are usually made of artificial polyamides like nylon, although nets of organic polyamides such as wool or silk thread were common until recently and...
; the meat is sometimes sold, but is considered to be of poorer quality than that of other houndsharks in the region. It is caught in lesser numbers off Taiwan
Taiwan
Taiwan , also known, especially in the past, as Formosa , is the largest island of the same-named island group of East Asia in the western Pacific Ocean and located off the southeastern coast of mainland China. The island forms over 99% of the current territory of the Republic of China following...
, and is probably also fished off Korea and northern China. The International Union for Conservation of Nature (IUCN) has listed the banded houndshark under Least Concern
Least Concern
Least Concern is an IUCN category assigned to extant taxon or lower taxa which have been evaluated but do not qualify for any other category. As such they do not qualify as threatened, Near Threatened, or Conservation Dependent...
, as it remains abundant throughout its range. Off Japan, it can be found in rocky areas that provide refuge from fishing pressure.