The
dwarf lanternshark (
Etmopterus perryi) is a little-known
speciesIn biology, a species is:* a taxonomic rank or* a unit at that rank ....
of
dogfish sharkSqualiformes is an order of sharks that includes about 80 species in seven families.Members of the order have two dorsal fins, which usually possess spines, no anal fin or nictitating membrane, and five gill slits. In most other respects, however, they are quite variable in form and size...
in the
familyIn 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...
EtmopteridaeEtmopteridae is a family of sharks in the order Squaliformes, commonly known as lantern sharks. Their name comes from the presence of light-producing photophores on their bodies...
and possibly the smallest shark in the world, reaching a maximum known length of . It is known to be present only on the upper continental slopes off
ColombiaColombia , officially the Republic of Colombia , is a constitutional republic in northwestern South America. Colombia is bordered to the east by Venezuela and Brazil; to the south by Ecuador and Peru; to the north by the Caribbean Sea; to the northwest by Panama; and to the west by the Pacific Ocean...
and
VenezuelaVenezuela , officially titled Bolivarian Republic of Venezuela , is a tropical country on the northern coast of South America. It is a continental mainland with numerous islands located off its coastline in the Caribbean Sea...
, at a depth of . This species can be identified by its small size at maturity, long flattened head, and pattern of black ventral markings and a mid-dorsal line.
The
dwarf lanternshark (
Etmopterus perryi) is a little-known
speciesIn biology, a species is:* a taxonomic rank or* a unit at that rank ....
of
dogfish sharkSqualiformes is an order of sharks that includes about 80 species in seven families.Members of the order have two dorsal fins, which usually possess spines, no anal fin or nictitating membrane, and five gill slits. In most other respects, however, they are quite variable in form and size...
in the
familyIn 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...
EtmopteridaeEtmopteridae is a family of sharks in the order Squaliformes, commonly known as lantern sharks. Their name comes from the presence of light-producing photophores on their bodies...
and possibly the smallest shark in the world, reaching a maximum known length of . It is known to be present only on the upper continental slopes off
ColombiaColombia , officially the Republic of Colombia , is a constitutional republic in northwestern South America. Colombia is bordered to the east by Venezuela and Brazil; to the south by Ecuador and Peru; to the north by the Caribbean Sea; to the northwest by Panama; and to the west by the Pacific Ocean...
and
VenezuelaVenezuela , officially titled Bolivarian Republic of Venezuela , is a tropical country on the northern coast of South America. It is a continental mainland with numerous islands located off its coastline in the Caribbean Sea...
, at a depth of . This species can be identified by its small size at maturity, long flattened head, and pattern of black ventral markings and a mid-dorsal line. Like other members of its
genusIn biology, a genus is a taxonomic unit used in the classification of living and fossil organisms. The term comes from Latin genus "descent, family, type, gender" , cognate with – genos, "race, stock, kin" ..In addition, genus is a taxonomic rank in the hierarchy In biology, a genus (plural:...
, it is capable of producing light from a distinctive array of
photophoreA photophore is a light-emitting organ which appears as luminous spots on various marine animals, including fish and cephalopods. The organ can be simple, or as complex as the human eye; equipped with lenses, shutters, color filters and reflectors...
s. Reproduction is ovoviviparous, with females
gestatingGestation is the carrying of an embryo or fetus inside a female viviparous animal. Mammals duringpregnancy can have one or more gestations at the same time ....
2–3 young at a time. The dwarf lanternshark is not significant to commercial fisheries but could be threatened by
mortalityMortality is the condition of being mortal, or susceptible to death; the opposite of immortalityIt may also refer to:* Mortality rate, a measure of the number of deaths in a given population* Mortality displacement* Mortality drag...
from bycatch; the degree of impact from human activities on its population is presently unknown.
Taxonomy and phylogeny
American ichthyologists
Stewart SpringerStewart 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,...
and
George H. BurgessGeorge H. Burgess is an ichthyologist and fisheries biologist with the Florida Museum of Natural History, University of Florida. He is the director of the International Shark Attack File and author/coauthor of numerous books and papers on sharks and other fish.George Burgess also appeared on...
described the dwarf lanternshark from specimens collected via trawling by the U.S. Fish and Wildlife Service research ship
Oregon in 1964. They named the new species in honor of noted shark biologist Perry W. Gilbert, and published their findings in a 1985
Copeia paper. The type specimen is a long female caught in the Caribbean Sea off the coast of
ColombiaColombia , officially the Republic of Colombia , is a constitutional republic in northwestern South America. Colombia is bordered to the east by Venezuela and Brazil; to the south by Ecuador and Peru; to the north by the Caribbean Sea; to the northwest by Panama; and to the west by the Pacific Ocean...
. This species is grouped with the
velvet belly lantern sharkThe velvet belly lantern shark , Etmopterus spinax, is a species of dogfish shark in the family Etmopteridae. One of the most common deepwater sharks in the northeastern Atlantic Ocean, the velvet belly is found from Iceland and Norway to Gabon and South Africa at a depth of...
(
E. spinax),
Caribbean lanternsharkThe Caribbean lanternshark, Etmopterus hillianus, is a shark of the family Dalatiidae found in the eastern and western Atlantic at depths of between 180 and 720 m. Its length is up to 50 cm.Reproduction is ovoviviparous.-References:...
(
E. hillianus),
fringefin lanternsharkThe fringefin lanternshark, Etmopterus schultzi, is a shark of the family Dalatiidae found in the western central Atlantic from Texas to Florida, northern Gulf of Mexico, and Mexico.-References:...
(
E. schultzi),
brown lanternsharkThe brown lanternshark, Etmopterus unicolor, is a little-known species of deep-sea dogfish shark in the family Etmopteridae. It is found off Japan and New Zealand, and possibly also South Africa and Australia, typically deeper than...
(
E. unicolor),
broadbanded lanternsharkThe broadbanded lanternshark, Etmopterus gracilispinis, is a shark of the family Dalatiidae found in the western and southeast Atlantic, between latitudes 40°N and 45°S, at depths of between 70 and 1,000 m...
(
E. gracilispinis), and
combtooth lanternsharkThe combtoothed lanternshark, Etmopterus decacuspidatus, is a shark of the family Dalatiidae the only specimen, and holotype, being found from the South China Sea between the Viet Nam coast and Hainan Island, at a depth of between 510 and 690 m...
(
E. decacuspidatus) in having irregularly arranged, needle-shaped
dermal denticleDenticles are body surface structures found on some fish and insects. Literally, the term means "small tooth" and refer to the structures' shape....
s.
Distribution and habitat
At present, the dwarf lanternshark has only been reported from a small area of the
Caribbean SeaThe Caribbean Sea is a sea of the Atlantic Ocean situated in the tropics of the Western hemisphere, bounded to the south and west by the American landmass, with the North Atlantic Ocean proper to the northeast and the Gulf of Mexico to the northwest...
off the coasts of
ColombiaColombia , officially the Republic of Colombia , is a constitutional republic in northwestern South America. Colombia is bordered to the east by Venezuela and Brazil; to the south by Ecuador and Peru; to the north by the Caribbean Sea; to the northwest by Panama; and to the west by the Pacific Ocean...
and
VenezuelaVenezuela , officially titled Bolivarian Republic of Venezuela , is a tropical country on the northern coast of South America. It is a continental mainland with numerous islands located off its coastline in the Caribbean Sea...
, occurring between
BarranquillaBarranquilla, an industrial, portuary, and special district, is a city and municipality located in northern Colombia by the Caribbean Sea. The capital of the Atlántico Department, it is the largest industrial city and port in the Colombian Caribbean region, and the fourth largest city in Colombia...
and
Santa MartaSanta Marta is a city and municipality located in northern Colombia by the Caribbean sea and the Sierra Nevada de Santa Marta mountains, capital of the Magdalena Department. The city is an important maritime port and hub for tourism, history and culture...
, near the
Guajira PeninsulaGuajira Peninsula , is a peninsula in northern Colombia and northwestern Venezuela in the Caribbean sea...
, and between the
Los Testigos IslandsLos Testigos Islands are a group of islands in the southeastern Caribbean Sea. They are a part of the Dependencias Federales of Venezuela.-Geography:...
and
GrenadaGrenada is an island country and sovereign state consisting of the island of Grenada and six smaller islands at the southern end of the Grenadines in the southeastern Caribbean Sea. Grenada is located northwest of Trinidad and Tobago, northeast of Venezuela, and southwest of Saint Vincent and the...
. This shark apparently inhabits the upper continental slope at a depth of .
Description
The dwarf lanternshark has a long, wide, flattened head comprising a fourth to a fifth of the total length. The eyes are large, twice as long as high, with the anterior and posterior corners acute. The nares are large and preceded by poorly developed flaps of skin. There are 25–32 tooth rows in the upper jaw and 30–34 tooth rows in the lower jaw. The upper teeth of adult males have a single cusp flanked by two pairs of smaller cusplets, while the upper teeth of females are more robust and have only one pair of lateral cusplets flanking the central cusp. The lower teeth each have a single, strongly oblique cusp, and their bases are interlocked to form a continuous cutting surface. There are scattered, sparse
papillaThe term papilla generally means a nipple-like structure, and may refer to:* Mammary papilla, or nipple* Interdental papilla, part of the gingiva between teeth* Dental papilla, cells involved in a developing tooth...
e inside the mouth and on the edges of the
gillA gill is an anatomical structure found in many aquatic organisms. It is a respiration organ whose function is the extraction of oxygen from water and the excretion of carbon dioxide...
arches. The five pairs of
gill slitGill 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 small.
The trunk is short, with two relatively closely-spaced, large
dorsal finA dorsal fin is a fin located on the backs of some fish, whales, dolphins, and porpoises, as well as the ichthyosaurs. Depending on the species, an animal can have up to three of them. Its main purpose is to stabilize the animal against rolling and assist in sudden turns...
s bearing grooved spines in front. The first dorsal fin originates over the trailing margins of the pectoral fins. The second dorsal fin has twice the area of the first and is larger than the pectoral or pelvic fins, and originates over the end of the pelvic fin bases. There is no anal fin. The caudal fin is low, with a moderate lower lobe and a ventral notch near the tip of the upper lobe. The skin is densely covered by thin, needle-like
dermal denticleDenticles are body surface structures found on some fish and insects. Literally, the term means "small tooth" and refer to the structures' shape....
s in a random pattern, except for the lips and the tips of the fins. This shark is dark brown with a striking and distinctive pattern of black markings on its ventral surface, a continuous or broken fine black line along the middle of its back (but without a white band like in the similar Caribbean lanternshark), a black band on the end of its caudal fin, and a dark blotch on its lower caudal fin lobe. Curiously, some of the ventral black markings are composed of light-producing
photophoreA photophore is a light-emitting organ which appears as luminous spots on various marine animals, including fish and cephalopods. The organ can be simple, or as complex as the human eye; equipped with lenses, shutters, color filters and reflectors...
s, while others (including the patch behind the pelvic fins) are composed of
pigmentA pigment is a material that changes the color of reflected or transmitted light as the result of wavelength-selective absorption. This physical process differs from fluorescence, phosphorescence, and other forms of luminescence, in which a material emits light.Many materials selectively absorb...
-containing
chromatophoreChromatophores are pigment-containing and light-reflecting cells found in amphibians, fish, reptiles, crustaceans, and cephalopods. They are largely responsible for generating skin and eye colour in cold-blooded animals and are generated in the neural crest during embryonic development...
s. The largest known individual is long.
Biology and ecology
Perhaps the smallest living shark species, male dwarf lanternsharks mature at a length of and females from a length of with long pregnant individuals known. The
spined pygmy sharkThe spined pygmy shark, Squaliolus laticaudus, is a species of dogfish shark in the family Dalatiidae found widely in all oceans. With a maximum known length of , it is one of the smallest living sharks. This shark has a slender, cigar-shaped body with a sizable conical snout, a long but low second...
(
Squaliolus laticaudus) and the
pygmy ribbontail catsharkThe pygmy ribbontail catshark, Eridacnis radcliffei, is a species of finback catshark, family Proscylliidae, distributed patchily in the western Indo-Pacific from Tanzania to the Philippines. It occurs around the edges of continental and insular shelves at a depth of , typically on or near mud...
(
Eridacnis radcliffei) are known to attain maturity at comparably small sizes; difficulties in assessing the reproductive maturity of sharks currently precludes stating one of these species as definitively smaller than the others. This species is ovoviviparous, with the developing
fetusA fetus is a developing mammal or other viviparous vertebrate after the embryonic stage and before birth. The plural is fetuses....
es being sustained by a
yolk sacThe yolk sac is a membranous sac attached to an embryo, providing early nourishment in the form of yolk in bony fishes, sharks, reptiles, birds, and primitive mammals...
until birth. Females bear litters of 2–3 young, each measuring long.
Human interactions
Because of its very small size, the dwarf lanternshark is of no economic value. Its low
fecundityFecundity, derived from the word fecund, generally refers to the ability to reproduce. In biology and demography, fecundity is the potential reproductive capacity of an organism or population, measured by the number of gametes , seed set or asexual propagules. Fecundity is under both genetic and...
and limited known range may merit concern if commercial fisheries in the region are taking it as bycatch, though presently there is insufficient information for the International Union for Conservation of Nature (IUCN) to assess it beyond
Data DeficientData Deficient is a category applied by the IUCN to a species when the available information is not sufficient for a proper assessment of conservation status to be made. This does not necessarily indicate that the species has not been extensively studied; but it does indicate that little or no...
.