Roughtail catshark
Encyclopedia
The roughtail catshark or marbled catshark (Galeus arae) is a common species
of catshark
, family
Scyliorhinidae. It is found at a depth of 36–702 m (118.1–2,303.1 ft) in the northwestern Atlantic Ocean
, the Gulf of Mexico
, and the Caribbean Sea
, from North Carolina
to Costa Rica
. Individuals of different sexes and ages are segregated to some degree. A small species not exceeding 33 cm (13 in) in length, the roughtail catshark has a slender body with a marbled color pattern of dark saddles and spots, and a prominent crest of enlarged dermal denticles along the dorsal edge of its caudal fin. This species feeds mainly on shrimp
and is oviparous. It is caught incidentally
in shrimp trawls, though trawl fisheries within its range mostly do not operate at the depths it inhabits. As a result, the International Union for Conservation of Nature has listed it under Least Concern
.
originally described the roughtail catshark as Pristiurus arae in a 1927 issue of American Museum Novitates. He named the species after the trawler Ara, which collected the first two specimens, both 16 cm (6.3 in) long immature females, off Miami Beach on March 31, 1926. Later authors have recognized Pristiurus as a junior synonym of Galeus
. The Antilles catshark
(G. antillensis) and the longfin sawtail catshark (G. cadenati) were regarded as subspecies
of G. arae, until taxonomic revisions were published by Hera Konstantinou and colleagues in 1998 and 2000. The three species, along with the southern
and Springer's sawtail catsharks (G. mincaronei and G. springeri), are grouped together in the G. arae species complex
.
While the full extent of its range may remain to be documented, the roughtail catshark seems to have a disjunct distribution
that does not overlap with that of either G. antillensis or G. cadenati. The northern population occurs from North Carolina
southward to Cuba
and the Yucatan Peninsula
, and westward to the Mississippi River Delta
. The southern population is found in the Caribbean Sea
off the coasts of Honduras
, Nicaragua
, and Costa Rica
.
The roughtail catshark is a demersal species typically inhabiting continental and insular slopes, occasionally venturing onto the shelf
. It is abundant but unevenly distributed, with some areas harboring hundreds of sharks and other areas none at all. Sharks of the northern population have been recorded from depths of 36–732 m (118.1–2,401.6 ft), and those of the southern population from 338 –. The shallowest records have tended to come from higher latitude
s, suggesting that temperature plays more of a role than depth in determining the species' distribution; it has been captured from water ranging from 5.6 to 11.1 °C (42.1 to 52 F). Both adults and juveniles occur up to a depth of 450 m (1,476.4 ft), while usually only adults are found deeper. There also appears to be spatial segregation by sex, though the patterns are not well-defined.
s (protective third eyelids), and lack prominent ridges underneath. There is a tiny spiracle
behind each eye. The mouth is large and forms a broad arch, with moderately long furrows around the corners. The teeth are small and number 59–65 rows in the upper jaw and 58–60 rows in the lower jaw. Each tooth has a thin central cusp flanked by 1–3 pairs of cusplets on either side. There are five pairs of gill slit
s.
The first dorsal fin
has a blunt apex and is positioned over the latter half of the pelvic fin bases. The second dorsal fin is nearly as large as the first and similar in shape, and positioned over the latter half of the anal fin base. The large, broad pectoral fins have rounded corners. The pelvic and anal fins are low and angular. The anal fin base measures roughly 10–14% of the total length, exceeding the distance between the pelvic and anal fins and about the same as the distance between the dorsal fins. The caudal fin is low, with a small lower lobe and a ventral notch near the tip of the upper lobe. The dermal denticles are small and overlapping; each has a leaf-shaped crown with a horizontal ridge and three marginal teeth. There is a prominent saw-toothed crest, formed from enlarged denticles, along the anterior portion of the dorsal caudal fin margin. This species is yellowish brown above with a marbled color pattern consisting of usually fewer than 11 dark saddles along the back and tail. Some smaller sharks have markings that form horizontal lines, while some larger sharks have round blotches along the sides. These markings can range from faint to well-defined by white outlines. The underside is pale, and the inside of the mouth is black.
, and may gather in sizable schools
. Once erroneously reported to be aplacental viviparous, more recent research has confirmed that this species is actually oviparous. Adult females have a single functional ovary
, on the right, and two functional oviduct
s. A single egg matures within each oviduct at a time. The eggs are enclosed within tough, flask-shaped capsules around 4.9–5.1 cm (1.9–2 in) long, 1.2–1.4 cm (0.47244094488189–0.551181102362205 in) across the top, and 1.6 cm (0.62992125984252 in) across the bottom. The rounded upper corners of the capsule bear coiled tendrils. The spawning grounds of this shark may be located in very rough terrain. Both sexes mature sexually
at approximately 27–33 cm (10.6–13 in) long.
in shrimp trawls. Shark expert Stewart Springer
reported in 1966 that it was frequently caught in shrimp trawls along the entire coast of Florida. The impact of trawl fisheries on this species in United States waters is unknown; its depth and spawning habitat preferences may offer a degree of protection from fishing pressure. Similarly, shrimp trawling activity off Central America does not extend into the depths occupied by this species. The International Union for Conservation of Nature (IUCN) has therefore assessed the roughtail catshark as of Least Concern
.
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 catshark
Catshark
Catsharks are ground sharks of the family Scyliorhinidae, with over 150 known species. While they are generally known as catsharks, many species are commonly called dogfish....
, 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...
Scyliorhinidae. It is found at a depth of 36–702 m (118.1–2,303.1 ft) in the northwestern Atlantic Ocean
Atlantic Ocean
The Atlantic Ocean is the second-largest of the world's oceanic divisions. With a total area of about , it covers approximately 20% of the Earth's surface and about 26% of its water surface area...
, the Gulf of Mexico
Gulf of Mexico
The Gulf of Mexico is a partially landlocked ocean basin largely surrounded by the North American continent and the island of Cuba. It is bounded on the northeast, north and northwest by the Gulf Coast of the United States, on the southwest and south by Mexico, and on the southeast by Cuba. In...
, and the Caribbean Sea
Caribbean Sea
The Caribbean Sea is a sea of the Atlantic Ocean located in the tropics of the Western hemisphere. It is bounded by Mexico and Central America to the west and southwest, to the north by the Greater Antilles, and to the east by the Lesser Antilles....
, from North Carolina
North Carolina
North Carolina is a state located in the southeastern United States. The state borders South Carolina and Georgia to the south, Tennessee to the west and Virginia to the north. North Carolina contains 100 counties. Its capital is Raleigh, and its largest city is Charlotte...
to Costa Rica
Costa Rica
Costa Rica , officially the Republic of Costa Rica is a multilingual, multiethnic and multicultural country in Central America, bordered by Nicaragua to the north, Panama to the southeast, the Pacific Ocean to the west and the Caribbean Sea to the east....
. Individuals of different sexes and ages are segregated to some degree. A small species not exceeding 33 cm (13 in) in length, the roughtail catshark has a slender body with a marbled color pattern of dark saddles and spots, and a prominent crest of enlarged dermal denticles along the dorsal edge of its caudal fin. This species feeds mainly on 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...
and is oviparous. It is 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...
in shrimp trawls, though trawl fisheries within its range mostly do not operate at the depths it inhabits. As a result, the International Union for Conservation of Nature 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
John T. Nichols of the American Museum of Natural HistoryAmerican Museum of Natural History
The American Museum of Natural History , located on the Upper West Side of Manhattan in New York City, United States, is one of the largest and most celebrated museums in the world...
originally described the roughtail catshark as Pristiurus arae in a 1927 issue of American Museum Novitates. He named the species after the trawler Ara, which collected the first two specimens, both 16 cm (6.3 in) long immature females, off Miami Beach on March 31, 1926. Later authors have recognized Pristiurus as a junior synonym of Galeus
Galeus
Galeus is a genus of catshark, family Scyliorhinidae, commonly known as sawtail catsharks in reference to a distinctive saw-toothed crest of enlarged dermal denticles found along the upper edges of their caudal fins. They are found in the Atlantic, the western and central Pacific, and the Gulf of...
. The Antilles catshark
Antilles catshark
The Antilles catshark is a common but little-known species of catshark, family Scyliorhinidae. It is found on or near the bottom at a depth of off Florida and the West Indies from Jamaica to Martinique. It was once regarded as a subspecies of the similar roughtail catshark , along with the...
(G. antillensis) and the longfin sawtail catshark (G. cadenati) were regarded as subspecies
Subspecies
Subspecies in biological classification, is either a taxonomic rank subordinate to species, ora taxonomic unit in that rank . A subspecies cannot be recognized in isolation: a species will either be recognized as having no subspecies at all or two or more, never just one...
of G. arae, until taxonomic revisions were published by Hera Konstantinou and colleagues in 1998 and 2000. The three species, along with the southern
Southern sawtail catshark
The southern sawtail catshark is a species of catshark, family Scyliorhinidae, endemic to southern Brazil. It inhabits deepwater reefs on the upper continental slope at a depth of . Reaching at least in length, this slim-bodied species closely resembles the Antilles catshark...
and Springer's sawtail catsharks (G. mincaronei and G. springeri), are grouped together in the G. arae species complex
Species complex
A species complex is a group of closely related species, where the exact demarcation between species is often unclear or cryptic owing to their recent and usually still incomplete reproductive isolation. Ring species, superspecies and cryptic species complex are example of species complex...
.
Distribution and habitat
Disjunct distribution
In biology, a taxon with a disjunct distribution is one that has two or more groups that are related but widely separated from each other geographically...
that does not overlap with that of either G. antillensis or G. cadenati. The northern population occurs from North Carolina
North Carolina
North Carolina is a state located in the southeastern United States. The state borders South Carolina and Georgia to the south, Tennessee to the west and Virginia to the north. North Carolina contains 100 counties. Its capital is Raleigh, and its largest city is Charlotte...
southward to Cuba
Cuba
The Republic of Cuba is an island nation in the Caribbean. The nation of Cuba consists of the main island of Cuba, the Isla de la Juventud, and several archipelagos. Havana is the largest city in Cuba and the country's capital. Santiago de Cuba is the second largest city...
and the Yucatan Peninsula
Yucatán Peninsula
The Yucatán Peninsula, in southeastern Mexico, separates the Caribbean Sea from the Gulf of Mexico, with the northern coastline on the Yucatán Channel...
, and westward to the Mississippi River Delta
Mississippi River Delta
The Mississippi River Delta is the modern area of land built up by alluvium deposited by the Mississippi River as it slows down and enters the Gulf of Mexico...
. The southern population is found in the Caribbean Sea
Caribbean Sea
The Caribbean Sea is a sea of the Atlantic Ocean located in the tropics of the Western hemisphere. It is bounded by Mexico and Central America to the west and southwest, to the north by the Greater Antilles, and to the east by the Lesser Antilles....
off the coasts of Honduras
Honduras
Honduras is a republic in Central America. It was previously known as Spanish Honduras to differentiate it from British Honduras, which became the modern-day state of Belize...
, Nicaragua
Nicaragua
Nicaragua is the largest country in the Central American American isthmus, bordered by Honduras to the north and Costa Rica to the south. The country is situated between 11 and 14 degrees north of the Equator in the Northern Hemisphere, which places it entirely within the tropics. The Pacific Ocean...
, and Costa Rica
Costa Rica
Costa Rica , officially the Republic of Costa Rica is a multilingual, multiethnic and multicultural country in Central America, bordered by Nicaragua to the north, Panama to the southeast, the Pacific Ocean to the west and the Caribbean Sea to the east....
.
The roughtail catshark is a demersal species typically inhabiting continental and insular slopes, occasionally venturing onto the shelf
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,...
. It is abundant but unevenly distributed, with some areas harboring hundreds of sharks and other areas none at all. Sharks of the northern population have been recorded from depths of 36–732 m (118.1–2,401.6 ft), and those of the southern population from 338 –. The shallowest records have tended to come from higher latitude
Latitude
In geography, the latitude of a location on the Earth is the angular distance of that location south or north of the Equator. The latitude is an angle, and is usually measured in degrees . The equator has a latitude of 0°, the North pole has a latitude of 90° north , and the South pole has a...
s, suggesting that temperature plays more of a role than depth in determining the species' distribution; it has been captured from water ranging from 5.6 to 11.1 °C (42.1 to 52 F). Both adults and juveniles occur up to a depth of 450 m (1,476.4 ft), while usually only adults are found deeper. There also appears to be spatial segregation by sex, though the patterns are not well-defined.
Description
Probably the smallest member of the G. arae species complex, the roughtail catshark grows no longer than 33 cm (13 in). It has a slender, firm body and a slightly flattened head. The snout is rather long and pointed, with the nostrils divided by triangular skin flaps in front. The horizontally oval eyes 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 lack prominent ridges underneath. There is a tiny spiracle
Spiracle
Spiracles are openings on the surface of some animals that usually lead to respiratory systems.-Vertebrates:The spiracle is a small hole behind each eye that opens to the mouth in some fishes. In the primitive jawless fish the first gill opening immediately behind the mouth is essentially similar...
behind each eye. The mouth is large and forms a broad arch, with moderately long furrows around the corners. The teeth are small and number 59–65 rows in the upper jaw and 58–60 rows in the lower jaw. Each tooth has a thin central cusp flanked by 1–3 pairs of cusplets on either side. 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.
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...
has a blunt apex and is positioned over the latter half of the pelvic fin bases. The second dorsal fin is nearly as large as the first and similar in shape, and positioned over the latter half of the anal fin base. The large, broad pectoral fins have rounded corners. The pelvic and anal fins are low and angular. The anal fin base measures roughly 10–14% of the total length, exceeding the distance between the pelvic and anal fins and about the same as the distance between the dorsal fins. The caudal fin is low, with a small lower lobe and a ventral notch near the tip of the upper lobe. The dermal denticles are small and overlapping; each has a leaf-shaped crown with a horizontal ridge and three marginal teeth. There is a prominent saw-toothed crest, formed from enlarged denticles, along the anterior portion of the dorsal caudal fin margin. This species is yellowish brown above with a marbled color pattern consisting of usually fewer than 11 dark saddles along the back and tail. Some smaller sharks have markings that form horizontal lines, while some larger sharks have round blotches along the sides. These markings can range from faint to well-defined by white outlines. The underside is pale, and the inside of the mouth is black.
Biology and ecology
The roughtail catshark preys mostly on shrimpShrimp
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...
, and may gather in sizable schools
Shoaling and schooling
In biology, any group of fish that stay together for social reasons are said to be shoaling , and if, in addition, the group is swimming in the same direction in a coordinated manner, they are said to be schooling . In common usage, the terms are sometimes used rather loosely...
. Once erroneously reported to be aplacental viviparous, more recent research has confirmed that this species is actually oviparous. Adult females have a single functional ovary
Ovary
The ovary is an ovum-producing reproductive organ, often found in pairs as part of the vertebrate female reproductive system. Ovaries in anatomically female individuals are analogous to testes in anatomically male individuals, in that they are both gonads and endocrine glands.-Human anatomy:Ovaries...
, on the right, and two functional oviduct
Oviduct
In non-mammalian vertebrates, the passageway from the ovaries to the outside of the body is known as the oviduct. The eggs travel along the oviduct. These eggs will either be fertilized by sperm to become a zygote, or will degenerate in the body...
s. A single egg matures within each oviduct at a time. The eggs are enclosed within tough, flask-shaped capsules around 4.9–5.1 cm (1.9–2 in) long, 1.2–1.4 cm (0.47244094488189–0.551181102362205 in) across the top, and 1.6 cm (0.62992125984252 in) across the bottom. The rounded upper corners of the capsule bear coiled tendrils. The spawning grounds of this shark may be located in very rough terrain. Both sexes mature sexually
Sexual maturity
Sexual maturity is the age or stage when an organism can reproduce. It is sometimes considered synonymous with adulthood, though the two are distinct...
at approximately 27–33 cm (10.6–13 in) long.
Human interactions
Harmless and of no commercial value, the roughtail catshark is too small to be caught on most types of fishing gear but is taken incidentallyBycatch
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...
in shrimp trawls. Shark expert Stewart Springer
Stewart Springer
Stewart Springer, was a world renowned expert on shark behavior, classification , and distribution of shark populations. There are more than 35 species of sharks, skates, rays, and other animals either classified originally by him or named after him.-Education:Springer was a field naturalist,...
reported in 1966 that it was frequently caught in shrimp trawls along the entire coast of Florida. The impact of trawl fisheries on this species in United States waters is unknown; its depth and spawning habitat preferences may offer a degree of protection from fishing pressure. Similarly, shrimp trawling activity off Central America does not extend into the depths occupied by this species. The International Union for Conservation of Nature (IUCN) has therefore assessed the roughtail catshark as of 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...
.