Lollipop catshark
Encyclopedia
The lollipop catshark, Cephalurus cephalus, is a little-known species
of deep sea
catshark
, family
Scyliorhinidae, and the only described member of its genus
. A diminutive, bottom-dwelling shark of the outer continental shelf
and upper continental slope, this species can be readily identified by its tadpole
-like shape with a greatly expanded, rounded head and narrow body. The large head houses expanded gill
s, which are thought to be an adaptation
for hypoxic conditions
. This shark preys on crustacean
s and fish
es. Reproduction is aplacental viviparous, with females retaining egg cases internally two at a time until they hatch. There is no fishery
interest in this species, and the International Union for Conservation of Nature (IUCN) lacks sufficient information to assess its conservation status.
as Catulus cephalus, in the 1892 14th volume of Proceedings of the United States National Museum. His description was based on a 24 cm (9.4 in) long adult male caught from a depth of 841 m (2,759.2 ft) off Clarion Island in the Revillagigedo Islands
. In 1941, Henry F. Bigelow
and William C. Schroeder created the new genus Cephalurus for this species. One or more yet-undescribed species of Cephalurus appear to exist off Panama
, Peru
, and Chile
, which differ slightly from C. cephalus in appearance and size.
Based on morphological
and molecular phylogenetic
evidence, Cephalurus is thought to form a clade
with the genera Asymbolus
, Parmaturus
, Galeus
, and Apristurus
. However, different authors disagree on the interrelationships within this group; molecular data supports Cephalurus and Parmaturus as sister groups.
to off the southern Baja peninsula. This benthic species occurs around the outer continental shelf
and upper continental slope at depths of 155–937 m (508.5–3,074.1 ft), where it is reportedly abundant.
-like shape, with an enormously expanded head and branchial region (containing the gills) coupled with a slender, cylindrical body tapering towards the tail. The head is wide, flattened, and rounded, comprising a third of the total length in adults. The snout is very short and blunt, with widely spaced nostril
s flanked by moderately developed flaps of skin. The mouth has a pair of furrows at the corners that curl around from the upper to the lower jaw. The widely spaced teeth have a large central cusp flanked by 1–3 cusplets on both sides; the upper teeth are straight while the lower teeth are curved somewhat outward. There are numerous small papilla
e on the tongue and roof of the mouth, and a light-colored membrane lining the inside of the mouth. The large eyes are oval in shape and followed by prominent spiracle
s. The five pairs of gill slit
s are distinctive, being strongly arched forward.
The body is very soft, almost gelatinous. Unlike in other catsharks, the first dorsal fin
originates well in front of the pelvic fins. The second dorsal fin is about as long and slightly lower than the first, and is positioned opposite the anal fin. The dorsal, pelvic, and anal fins have convex leading and nearly straight trailing margins. The pectoral fins are angular, twice as long as wide, and originate beneath the fourth gill slit. The caudal fin is low, with an indistinct lower lobe and a shallow ventral notch near the tip of the upper lobe. The skin is delicate and sparsely covered by thorn-like dermal denticles interspersed with narrower hair-like denticles that become more numerous on the back. The coloration is a plain brownish gray all over, sometimes lightening to almost white at the dorsal, pectoral, and pelvic fin margins. The eyes are an iridescent green. Adults typically attain a length of 24 cm (9.4 in), but may grow up to 28 cm (11 in) long.
for living in deep-sea basins with very low levels of dissolved oxygen and perhaps also high temperatures and salinity
. This shark feeds mainly on crustacean
s, followed by fish
es. The lollipop catshark is aplacental viviparous, with birthing apparently taking place in early summer. Females have two functional ovaries and retain pairs of thin-shelled egg cases (one within each oviduct
) within their bodies until they hatch. Newborns measure about 10 cm (3.9 in) long; sexual maturation is reached at a length of 19 cm (7.5 in) for males and 24 cm (9.4 in) for females.
; though the depths at which it occupies may offer some protection from fishing pressure. The International Union for Conservation of Nature (IUCN) presently lacks the information to assess it beyond Data Deficient
.
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 deep sea
Deep sea
The deep sea, or deep layer, is the lowest layer in the ocean, existing below the thermocline and above the seabed, at a depth of 1000 fathoms or more. Little or no light penetrates this part of the ocean and most of the organisms that live there rely for subsistence on falling organic matter...
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, and the only described member of its genus
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
. A diminutive, bottom-dwelling shark of the outer continental 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,...
and upper continental slope, this species can be readily identified by its tadpole
Tadpole
A tadpole or polliwog is the wholly aquatic larval stage in the life cycle of an amphibian, particularly that of a frog or toad.- Appellation :...
-like shape with a greatly expanded, rounded head and narrow body. The large head houses expanded gill
Gill
A gill is a respiratory organ found in many aquatic organisms that extracts dissolved oxygen from water, afterward excreting carbon dioxide. The gills of some species such as hermit crabs have adapted to allow respiration on land provided they are kept moist...
s, which are thought to be an adaptation
Adaptation
An adaptation in biology is a trait with a current functional role in the life history of an organism that is maintained and evolved by means of natural selection. An adaptation refers to both the current state of being adapted and to the dynamic evolutionary process that leads to the adaptation....
for hypoxic conditions
Hypoxia (environmental)
Hypoxia, or oxygen depletion, is a phenomenon that occurs in aquatic environments as dissolved oxygen becomes reduced in concentration to a point where it becomes detrimental to aquatic organisms living in the system...
. This shark preys on 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 and fish
Fish
Fish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish, as well as various extinct related groups...
es. Reproduction is aplacental viviparous, with females retaining egg cases internally two at a time until they hatch. There is no fishery
Fishery
Generally, a fishery is an entity engaged in raising or harvesting fish which is determined by some authority to be a fishery. According to the FAO, a fishery is typically defined in terms of the "people involved, species or type of fish, area of water or seabed, method of fishing, class of boats,...
interest in this species, and the International Union for Conservation of Nature (IUCN) lacks sufficient information to assess its conservation status.
Taxonomy and phylogeny
The lollipop catshark was originally described by American ichthyologist Charles Henry GilbertCharles Henry Gilbert
Charles Henry Gilbert was a pioneer ichthyologist and fishery biologist of particular significance to natural history of the western United States. He collected and studied fishes from Central America north to Alaska and described many new species...
as Catulus cephalus, in the 1892 14th volume of Proceedings of the United States National Museum. His description was based on a 24 cm (9.4 in) long adult male caught from a depth of 841 m (2,759.2 ft) off Clarion Island in the Revillagigedo Islands
Revillagigedo Islands
The Revillagigedo Islands or Revillagigedo Archipelago are a group of four volcanic islands in the Pacific Ocean, known for their unique ecosystem...
. In 1941, Henry F. Bigelow
Henry Forbes Bigelow
Henry Forbes Bigelow was a Boston, Massachusetts architect in the firm Bigelow and Wadsworth. He became a partner in the firm in 1898.-Biography:...
and William C. Schroeder created the new genus Cephalurus for this species. One or more yet-undescribed species of Cephalurus appear to exist off Panama
Panama
Panama , officially the Republic of Panama , is the southernmost country of Central America. Situated on the isthmus connecting North and South America, it is bordered by Costa Rica to the northwest, Colombia to the southeast, the Caribbean Sea to the north and the Pacific Ocean to the south. The...
, Peru
Peru
Peru , officially the Republic of Peru , is a country in western South America. It is bordered on the north by Ecuador and Colombia, on the east by Brazil, on the southeast by Bolivia, on the south by Chile, and on the west by the Pacific Ocean....
, and Chile
Chile
Chile ,officially the Republic of Chile , is a country in South America occupying a long, narrow coastal strip between the Andes mountains to the east and the Pacific Ocean to the west. It borders Peru to the north, Bolivia to the northeast, Argentina to the east, and the Drake Passage in the far...
, which differ slightly from C. cephalus in appearance and size.
Based on morphological
Morphology (biology)
In biology, morphology is a branch of bioscience dealing with the study of the form and structure of organisms and their specific structural features....
and molecular phylogenetic
Molecular phylogeny
Molecular phylogenetics is the analysis of hereditary molecular differences, mainly in DNA sequences, to gain information on an organism's evolutionary relationships. The result of a molecular phylogenetic analysis is expressed in a phylogenetic tree...
evidence, Cephalurus is thought to form 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 the genera Asymbolus
Asymbolus
Asymbolus is a genus of catshark in the family Scyliorhinidae.-Species:* Asymbolus analis * Asymbolus funebris Compagno, Stevens & Last, 1999...
, Parmaturus
Parmaturus
Parmaturus is a genus of catshark in the family Scyliorhinidae.-Species:* Parmaturus albimarginatus Séret & Last, 2007 * Parmaturus albipenis Séret & Last, 2007...
, 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...
, and 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...
. However, different authors disagree on the interrelationships within this group; molecular data supports Cephalurus and Parmaturus as sister groups.
Distribution and habitat
The range of the lollipop catshark extends from the Gulf of CaliforniaGulf of California
The Gulf of California is a body of water that separates the Baja California Peninsula from the Mexican mainland...
to off the southern Baja peninsula. This benthic species occurs around the outer continental 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,...
and upper continental slope at depths of 155–937 m (508.5–3,074.1 ft), where it is reportedly abundant.
Description
The lollipop catshark is so named because of its peculiar tadpoleTadpole
A tadpole or polliwog is the wholly aquatic larval stage in the life cycle of an amphibian, particularly that of a frog or toad.- Appellation :...
-like shape, with an enormously expanded head and branchial region (containing the gills) coupled with a slender, cylindrical body tapering towards the tail. The head is wide, flattened, and rounded, comprising a third of the total length in adults. The snout is very short and blunt, with widely spaced nostril
Nostril
A nostril is one of the two channels of the nose, from the point where they bifurcate to the external opening. In birds and mammals, they contain branched bones or cartilages called turbinates, whose function is to warm air on inhalation and remove moisture on exhalation...
s flanked by moderately developed flaps of skin. The mouth has a pair of furrows at the corners that curl around from the upper to the lower jaw. The widely spaced teeth have a large central cusp flanked by 1–3 cusplets on both sides; the upper teeth are straight while the lower teeth are curved somewhat outward. There are numerous small papilla
Papilla (fish mouth structure)
The papilla, in certain kinds of fish, particularly rays, sharks, and catfish, are small lumps of dermal tissue found in the mouth, where they are "distributed uniformly on the tongue, palate, and pharynx"...
e on the tongue and roof of the mouth, and a light-colored membrane lining the inside of the mouth. The large eyes are oval in shape and followed by prominent 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...
s. The 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 are distinctive, being strongly arched forward.
The body is very soft, almost gelatinous. Unlike in other catsharks, 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...
originates well in front of the pelvic fins. The second dorsal fin is about as long and slightly lower than the first, and is positioned opposite the anal fin. The dorsal, pelvic, and anal fins have convex leading and nearly straight trailing margins. The pectoral fins are angular, twice as long as wide, and originate beneath the fourth gill slit. The caudal fin is low, with an indistinct lower lobe and a shallow ventral notch near the tip of the upper lobe. The skin is delicate and sparsely covered by thorn-like dermal denticles interspersed with narrower hair-like denticles that become more numerous on the back. The coloration is a plain brownish gray all over, sometimes lightening to almost white at the dorsal, pectoral, and pelvic fin margins. The eyes are an iridescent green. Adults typically attain a length of 24 cm (9.4 in), but may grow up to 28 cm (11 in) long.
Biology and ecology
The enlarged gill region and expanded gill filaments of the lollipop catshark suggest that it is adaptedAdaptation
An adaptation in biology is a trait with a current functional role in the life history of an organism that is maintained and evolved by means of natural selection. An adaptation refers to both the current state of being adapted and to the dynamic evolutionary process that leads to the adaptation....
for living in deep-sea basins with very low levels of dissolved oxygen and perhaps also high temperatures and salinity
Salinity
Salinity is the saltiness or dissolved salt content of a body of water. It is a general term used to describe the levels of different salts such as sodium chloride, magnesium and calcium sulfates, and bicarbonates...
. This shark feeds mainly on 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, followed by fish
Fish
Fish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish, as well as various extinct related groups...
es. The lollipop catshark is aplacental viviparous, with birthing apparently taking place in early summer. Females have two functional ovaries and retain pairs of thin-shelled egg cases (one within each 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...
) within their bodies until they hatch. Newborns measure about 10 cm (3.9 in) long; sexual maturation is reached at a length of 19 cm (7.5 in) for males and 24 cm (9.4 in) for females.
Human interactions
The lollipop catshark is of no significance to fisheries. It may be taken as bycatchBycatch
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...
; though the depths at which it occupies may offer some protection from fishing pressure. The International Union for Conservation of Nature (IUCN) presently lacks the information to assess it beyond Data Deficient
Data Deficient
Data Deficient is a category applied by the IUCN, other agencies, and individuals to a species when the available information is not sufficient for a proper assessment of conservation status to be made...
.