Mouse catshark
Encyclopedia
The mouse catshark is a species
of catshark
, family
Scyliorhinidae, common in the northeastern Atlantic Ocean
, from Iceland
to Western Sahara
. There is much taxonomic confusion regarding this species in Icelandic waters, where it may be confounded with another species of Galeus
or Apristurus
. Probably not exceeding 49 cm (19.3 in) long, the mouse catshark has a uniformly brown body and is characterized by large, rounded pelvic fins and crests of enlarged dermal denticles along both the dorsal and ventral caudal fin margins. In addition, in adult males the inner margins of the pelvic fins are merged into an "apron".
Demersal in nature, the mouse catshark inhabits continental slopes at a depth of 380–1300 m (1,246.7–4,265.1 ft). It preys mainly on benthic crustacean
s, bony fishes, and cephalopod
s. Reproduction is oviparous, with females producing "furry" egg capsules. Although it is caught incidentally
by commercial
trawl fisheries, this species does not appear to be threatened by fishing activities and has been listed under Least Concern
by the International Union for Conservation of Nature (IUCN).
originally described the mouse catshark as Pristiurus murinus, in a 1904 issue of the scientific journal
Forhandlinger i Videnskabs-selskabet i Christiania; its specific epithet means "relating to a mouse" in Latin
. The type specimen is an immature female 22 cm (8.7 in) long, collected 150 km (93.2 mi) northwest of the Hebrides
at a depth of 1100–1300 m (3,608.9–4,265.1 ft). Later authors have recognized Pristiurus as a junior synonym of Galeus
.
Some taxonomic confusion has arisen over Pristiurus jensenii, described from Iceland
by Bjarni Sæmundsson in 1922, which has traditionally been regarded to be the same species as G. murinus. Recently reported data for G. murinus have shown inconsistencies between sharks from Iceland and elsewhere, suggesting that P. jensenii may in fact be a valid species very similar to G. murinus. However, an alternate possibility is that some of the data may have been confounded with a species of Apristurus
. The placement of G. murinus within Galeus is problematic as it does not much resemble the more typical members of the genus. On the other hand, a 2005 phylogenetic analysis by Samuel Iglésias and colleagues, based on mitochondrial
and nuclear DNA
, found that G. murinus forms a clade
with G. melastomus
, apart from the clade of G. eastmani
, G. sauteri
, and G. gracilis
.
and the Faroe Islands
to the Hebrides, Scotland
, and Ireland
, to as far south as France
and Western Sahara
. This species is found on or near the bottom over the continental slope, in water 380–1300 m (1,246.7–4,265.1 ft) deep. It has been reported from a depth of 656–1731 m (2,152.2–5,679.1 ft) off Iceland, but the figure is confounded by taxonomic confusion.
s (protective third eyelids). A thin ridge is present beneath each eye, and a tiny spiracle
behind. The large mouth forms a wide arch, and bears well-developed furrows at the corners. The teeth have a narrow central cusp and multiple lateral cusplets on either side. There are five pairs of gill slit
s.
The first dorsal fin
has a rounded tip and is positioned over the aft portion of the pelvic fins. The second dorsal fin is similar in size and shape as the first, and is positioned over the aft portion of the anal fin. The pectoral fins are large and broad. The pelvic fins are distinctive, being large and wide with an evenly rounded margin. In adult males, the inner margins of the pelvic fins are fused together to form an "apron" partially covering the claspers. The anal fin is large and angular; its base measures roughly 12–13% of the total length, much longer than the distance between the dorsal fins. The pelvic, anal, and caudal fins are all very close to each other. The caudal peduncle is cylindrical and 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 an arrowhead-shaped crown bearing a horizontal ridge and three marginal teeth. There is a prominent crest of enlarged denticles along the dorsal caudal fin margin. Unusually for the genus, there is also a similar denticle crest along the underside of the caudal peduncle, extending to the forward portion of the ventral caudal fin margin. This shark is plain brown, lightening slightly on the underside; the interior of the mouth is dark.
such as Pasiphaea multidentata and Sergestes robustus, other crustacean
s such as Dorhynchus thomsoni, bony fishes such as Micromesistius poutassou, and cephalopod
s. Most prey organisms are captured on or close to the sea floor. Reproduction is oviparous; the female has two oviduct
s, with one egg maturing inside each at a time. The egg capsules are golden yellow and vase-shaped, measuring 5.4–5.6 cm (2.1–2.2 in) long and 1.4–1.7 cm (0.551181102362205–0.669291338582677 in) across. The top of the capsule is squared off, while the bottom comes to a short projection. The capsule surface is thickly covered by fibers, giving it a hairy appearance. The young are estimated to hatch at a length of approximately 8–9 cm (3.1–3.5 in).
by commercial
trawl fisheries operating in deep water off Europe and western Africa. However, it may be small enough to escape most nets, and there are likely parts of its wide range that see little fishing activity. Because there are no substantial threats to its population, the International Union for Conservation of Nature (IUCN) has assessed this species 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, common in the northeastern 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...
, from Iceland
Iceland
Iceland , described as the Republic of Iceland, is a Nordic and European island country in the North Atlantic Ocean, on the Mid-Atlantic Ridge. Iceland also refers to the main island of the country, which contains almost all the population and almost all the land area. The country has a population...
to Western Sahara
Western Sahara
Western Sahara is a disputed territory in North Africa, bordered by Morocco to the north, Algeria to the northeast, Mauritania to the east and south, and the Atlantic Ocean to the west. Its surface area amounts to . It is one of the most sparsely populated territories in the world, mainly...
. There is much taxonomic confusion regarding this species in Icelandic waters, where it may be confounded with another species 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...
or Apristurus
Apristurus
Apristurus is a genus of catshark, the family Scyliorhinidae, commonly known as the ghost or demon catsharks.-Species:* Apristurus albisoma Nakaya & Séret, 1999* Apristurus ampliceps Sasahara, Sato & Nakaya, 2008...
. Probably not exceeding 49 cm (19.3 in) long, the mouse catshark has a uniformly brown body and is characterized by large, rounded pelvic fins and crests of enlarged dermal denticles along both the dorsal and ventral caudal fin margins. In addition, in adult males the inner margins of the pelvic fins are merged into an "apron".
Demersal in nature, the mouse catshark inhabits continental slopes at a depth of 380–1300 m (1,246.7–4,265.1 ft). It preys mainly on benthic crustacean
Crustacean
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, bony fishes, and 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. Reproduction is oviparous, with females producing "furry" egg capsules. Although 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...
by commercial
Commercial fishing
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 pursue fish far into the ocean under adverse conditions...
trawl fisheries, this species does not appear to be threatened by fishing activities and has been listed 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...
by the International Union for Conservation of Nature (IUCN).
Taxonomy and phylogeny
Norwegian zoologist Robert CollettRobert Collett
Robert Collett was a Norwegian zoologist. He worked with vertebrates, primarily fishes. From 1864 he was curator at the Zoological Museum in Oslo. In 1882 he became its director and from 1884 was a professor there...
originally described the mouse catshark as Pristiurus murinus, in a 1904 issue of the scientific journal
Scientific journal
In academic publishing, a scientific journal is a periodical publication intended to further the progress of science, usually by reporting new research. There are thousands of scientific journals in publication, and many more have been published at various points in the past...
Forhandlinger i Videnskabs-selskabet i Christiania; its specific epithet means "relating to a mouse" in Latin
Latin
Latin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...
. The type specimen is an immature female 22 cm (8.7 in) long, collected 150 km (93.2 mi) northwest of the Hebrides
Hebrides
The Hebrides comprise a widespread and diverse archipelago off the west coast of Scotland. There are two main groups: the Inner and Outer Hebrides. These islands have a long history of occupation dating back to the Mesolithic and the culture of the residents has been affected by the successive...
at a depth of 1100–1300 m (3,608.9–4,265.1 ft). 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...
.
Some taxonomic confusion has arisen over Pristiurus jensenii, described from Iceland
Iceland
Iceland , described as the Republic of Iceland, is a Nordic and European island country in the North Atlantic Ocean, on the Mid-Atlantic Ridge. Iceland also refers to the main island of the country, which contains almost all the population and almost all the land area. The country has a population...
by Bjarni Sæmundsson in 1922, which has traditionally been regarded to be the same species as G. murinus. Recently reported data for G. murinus have shown inconsistencies between sharks from Iceland and elsewhere, suggesting that P. jensenii may in fact be a valid species very similar to G. murinus. However, an alternate possibility is that some of the data may have been confounded with a species of Apristurus
Apristurus
Apristurus is a genus of catshark, the family Scyliorhinidae, commonly known as the ghost or demon catsharks.-Species:* Apristurus albisoma Nakaya & Séret, 1999* Apristurus ampliceps Sasahara, Sato & Nakaya, 2008...
. The placement of G. murinus within Galeus is problematic as it does not much resemble the more typical members of the genus. On the other hand, a 2005 phylogenetic analysis by Samuel Iglésias and colleagues, based on mitochondrial
Mitochondrial DNA
Mitochondrial DNA is the DNA located in organelles called mitochondria, structures within eukaryotic cells that convert the chemical energy from food into a form that cells can use, adenosine triphosphate...
and nuclear DNA
Nuclear DNA
Nuclear DNA, nuclear deoxyribonucleic acid , is DNA contained within a nucleus of eukaryotic organisms. In mammals and vertebrates, nuclear DNA encodes more of the genome than the mitochondrial DNA and is composed of information inherited from two parents, one male, and one female, rather than...
, found that G. murinus forms a clade
Clade
A clade is a group consisting of a species and all its descendants. In the terms of biological systematics, a clade is a single "branch" on the "tree of life". The idea that such a "natural group" of organisms should be grouped together and given a taxonomic name is central to biological...
with G. melastomus
Blackmouth catshark
The blackmouth catshark is a species of catshark, family Scyliorhinidae, common in the northeastern Atlantic Ocean from Iceland to Senegal, including the Mediterranean Sea. It is typically found over the continental slope at depths of , on or near muddy bottoms. The youngest sharks generally...
, apart from the clade of G. eastmani
Gecko catshark
The gecko catshark is a species of catshark, family Scyliorhinidae, native to the northwestern Pacific Ocean from southern Japan to Taiwan, and possibly also off Vietnam. It is a common, demersal species found at depths of . Its body is slender, with a pattern of dark saddles and blotches...
, G. sauteri
Blacktip sawtail catshark
The blacktip sawtail catshark is a species of catshark, family Scyliorhinidae, found off Taiwan and the Philippines. It is demersal in nature and occurs deeper than...
, and G. gracilis
Slender sawtail catshark
The slender sawtail catshark is a little-known species of catshark, family Scyliorhinidae, endemic to northern Australia. It is found over the continental slope in on water...
.
Distribution and habitat
Fairly common, the mouse catshark has recently been found to be more widespread in the northeastern Atlantic than previously thought, occurring from western IcelandIceland
Iceland , described as the Republic of Iceland, is a Nordic and European island country in the North Atlantic Ocean, on the Mid-Atlantic Ridge. Iceland also refers to the main island of the country, which contains almost all the population and almost all the land area. The country has a population...
and the Faroe Islands
Faroe Islands
The Faroe Islands are an island group situated between the Norwegian Sea and the North Atlantic Ocean, approximately halfway between Scotland and Iceland. The Faroe Islands are a self-governing territory within the Kingdom of Denmark, along with Denmark proper and Greenland...
to the Hebrides, Scotland
Scotland
Scotland is a country that is part of the United Kingdom. Occupying the northern third of the island of Great Britain, it shares a border with England to the south and is bounded by the North Sea to the east, the Atlantic Ocean to the north and west, and the North Channel and Irish Sea to the...
, and Ireland
Ireland
Ireland is an island to the northwest of continental Europe. It is the third-largest island in Europe and the twentieth-largest island on Earth...
, to as far south as France
France
The French Republic , The French Republic , The French Republic , (commonly known as France , is a unitary semi-presidential republic in Western Europe with several overseas territories and islands located on other continents and in the Indian, Pacific, and Atlantic oceans. Metropolitan France...
and Western Sahara
Western Sahara
Western Sahara is a disputed territory in North Africa, bordered by Morocco to the north, Algeria to the northeast, Mauritania to the east and south, and the Atlantic Ocean to the west. Its surface area amounts to . It is one of the most sparsely populated territories in the world, mainly...
. This species is found on or near the bottom over the continental slope, in water 380–1300 m (1,246.7–4,265.1 ft) deep. It has been reported from a depth of 656–1731 m (2,152.2–5,679.1 ft) off Iceland, but the figure is confounded by taxonomic confusion.
Description
The maximum length of the mouse catshark has been variously reported as 49 cm (19.3 in) and 85 cm (33.5 in). The larger figure comes from Iceland and is reflective of the aforementioned taxonomic confusion, as the specimen of P. jensenii described by Sæmundsson was 63 cm (24.8 in) long. This species has a firm body with a rather long, blunt snout. The nostrils are divided by triangular flaps of skin in front. The eyes are horizontally oval and 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). A thin ridge is present beneath each eye, and 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. The large mouth forms a wide arch, and bears well-developed furrows at the corners. The teeth have a narrow central cusp and multiple lateral 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 rounded tip and is positioned over the aft portion of the pelvic fins. The second dorsal fin is similar in size and shape as the first, and is positioned over the aft portion of the anal fin. The pectoral fins are large and broad. The pelvic fins are distinctive, being large and wide with an evenly rounded margin. In adult males, the inner margins of the pelvic fins are fused together to form an "apron" partially covering the claspers. The anal fin is large and angular; its base measures roughly 12–13% of the total length, much longer than the distance between the dorsal fins. The pelvic, anal, and caudal fins are all very close to each other. The caudal peduncle is cylindrical and 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 an arrowhead-shaped crown bearing a horizontal ridge and three marginal teeth. There is a prominent crest of enlarged denticles along the dorsal caudal fin margin. Unusually for the genus, there is also a similar denticle crest along the underside of the caudal peduncle, extending to the forward portion of the ventral caudal fin margin. This shark is plain brown, lightening slightly on the underside; the interior of the mouth is dark.
Biology and ecology
The diet of the mouse catshark consists primarily of 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...
such as Pasiphaea multidentata and Sergestes robustus, other crustacean
Crustacean
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 such as Dorhynchus thomsoni, bony fishes such as Micromesistius poutassou, and 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. Most prey organisms are captured on or close to the sea floor. Reproduction is oviparous; the female has two 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, with one egg maturing inside each at a time. The egg capsules are golden yellow and vase-shaped, measuring 5.4–5.6 cm (2.1–2.2 in) long and 1.4–1.7 cm (0.551181102362205–0.669291338582677 in) across. The top of the capsule is squared off, while the bottom comes to a short projection. The capsule surface is thickly covered by fibers, giving it a hairy appearance. The young are estimated to hatch at a length of approximately 8–9 cm (3.1–3.5 in).
Human interactions
The mouse catshark is frequently caught 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...
by commercial
Commercial fishing
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 pursue fish far into the ocean under adverse conditions...
trawl fisheries operating in deep water off Europe and western Africa. However, it may be small enough to escape most nets, and there are likely parts of its wide range that see little fishing activity. Because there are no substantial threats to its population, the International Union for Conservation of Nature (IUCN) has assessed this species 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...
.