Blotchy swell shark
Encyclopedia
The blotchy swell shark or Japanese swellshark (Cephaloscyllium umbratile) is a common species
of catshark
, family
Scyliorhinidae, found at depths of 90–200 m (295.3–656.2 ft) in the northwestern Pacific Ocean
from Japan
to Taiwan
. It is benthic in nature and favors rocky reef
s. Reaching 1.4 m (4.6 ft) in length, this thick-bodied shark has a broad head, large mouth, and two unequally-sized dorsal fin
s positioned far back past the pelvic fins. It can be identified by its dorsal coloration, consisting of seven brown "saddles" and extensive darker mottling on a light tan background. This species has often been confounded with the draughtsboard shark
(C. isabellum) and the Sarawak pygmy swellshark (C. sarawakensis) in scientific literature
.
Voracious and opportunistic in feeding habits, the blotchy swell shark is known to consume numerous types of fish
es and invertebrate
s, including an unusually high diversity of cartilaginous fishes. Like other Cephaloscyllium species, it is capable of rapidly inflating its body as a defense against predators. This species is oviparous, with females laying encapsulated eggs two at a time. There is no well-defined breeding season
and reproduction occurs year-round. The eggs hatch after approximately one year. The blotchy swell shark is harmless and fares well in captivity. It is caught as bycatch
in commercial
bottom trawls, though its population does not seem to have suffered from fishing activity. The International Union for Conservation of Nature (IUCN) presently lacks sufficient information to assess its conservation status.
and Henry Weed Fowler
described the blotchy swell shark in a 1903 volume of Proceedings of the United States National Museum, based on a 98 cm (38.6 in) long stuffed dry skin
originally obtained from Nagasaki
, Japan. They gave it the specific epithet umbratile (from the Latin
umbratilis, meaning "shaded") and assigned it to the genus
Cephaloscyllium.
The taxonomy
of the blotchy swell shark has a history of confusion. The holotype
dried skin could not be located when shark expert Stewart Springer
perpared his 1979 review of the catsharks, and in its absence he synonymized C. umbratile with C. isabellum
on the basis of "inconclusive morphometric differences". Some authors followed Springer's judgment while others, particularly in Japan, preferred to keep referring to C. umbratile. The taxonomy of this species was further muddled by the application of the name C. umbratile to a similar but smaller species sharing part of its range. This second species, once referred to as "pseudo-umbratile" by Leonard Compagno
, has since been identified as C. sarawakensis. Recently, the holotype was found again, and in 2008 Cephaloscyllium umbratile was re-described as distinct from C. isabellum by Jayna Schaaf-Da Silva and David Ebert.
from Hokkaido
, Japan
southward to Taiwan
, including the Yellow Sea
. Its range may extend as far as New Guinea
. This abundant species is a bottom-dweller that inhabits rocky reef
s on the continental shelf
, at a depth of 90–200 m (295.3–656.2 ft).
s (protective third eyelids). A tiny spiracle
lies closely behind each eye. Behind the spiracle are five pairs of gill slit
s, which are short and become progressively smaller posteriorly. The capacious mouth forms a broad arch, and lacks furrows at the corners. The small teeth have a central cusp flanked by a smaller cusplet on both sides. There are around 59 tooth rows in the upper jaw and 62 tooth rows in the lower jaw.
The pectoral fins are moderately large and wide, with rounded tips. The dorsal fin
s have rounded apexes and are placed well back on the body, the first originating behind the midpoints of the small pelvic fins. The first dorsal fin is about twice as high as the second. The anal fin is nearly as large as the first dorsal fin and placed slightly ahead of the second dorsal fin. The caudal fin is large and broad, with the upper lobe longer than the lower and bearing a prominent ventral notch near the tip. The skin is thick and sparsely covered by large, well-calcified
dermal denticles; each denticle has a diamond-shaped crown with three horizontal ridges. This shark is cream-colored with dark brownish to grayish mottling on the back and sides, and seven dark brown dorsal "saddles" on the body and tail. The mottling intensifies with age, while the saddles fade and may become obscured. Older sharks may also have a dark blotch on either side between the pectoral and pelvic fins. The underside is pale, with scant darker marks.
, when threatened the blotchy swell shark is capable of rapidly inflating its stomach
with water or air. This allows the shark to wedge itself inside a rocky crevice, becoming extremely difficult to remove. This species is an opportunistic, highly voracious predator; one recorded female 1 m (3.3 ft) long had 10 fish about 20 cm (7.9 in) long and 15 squid about 15 cm (5.9 in) long in her stomach. Predominantly piscivorous, this species is known to prey upon hagfish
and at least 50 species of bony fishes, including fast-swimming types that inhabit open water; significant prey species include the mackerel
Scomber japonicus, the sardine
Sardinops melanostictus, the filefish
Thamnaconus modestus, and the hakeling
Physiculus japonicus. Unusually for such a small shark, it also feeds on at least 10 species of cartilaginous fishes, including lantern shark
s, catshark
s (particularly the cloudy catshark
, Scyliorhinus torazame, and its eggs), the electric ray
Narke japonica, and skate
s (including their eggs). It also cannibalizes
smaller members of its own species. Cephalopod
s, mostly the squid
Doryteuthis bleekeri and the cuttlefish
Sepia
spp., are also frequently taken, while crab
s, shrimp
, and isopods are occasionally consumed. The dietary composition of juveniles varies notably from place to place.
The blotchy swell shark is oviparous, and reproduction proceeds throughout the year with no obvious seasonal cycling. Adult females have a single functional ovary
, on the right, and two functional oviduct
s. The species is thought to be relatively prolific, as the ovary contains numerous ova
at various stages of development. Pairs of eggs are laid at a time, one per oviduct. Females have been documented producing eggs even after years without male contact, suggesting that they may be able to store sperm
. The purse-shaped egg capsules are relatively large and thick, measuring around 12 cm (4.7 in) long and 7 cm (2.8 in) across. The capsule surface is smooth with lengthwise striations, and opaque cream in color with yellow margins. Long, coiled tendrils extend from the four corners of the capsule. When the embryo
is 11 cm (4.3 in) long, the external gills
have been lost, the dermal denticles have begun to develop, and light brown saddles are present. The eggs take roughly one year to hatch; newly emerged sharks measure 16–22 cm (6.3–8.7 in) long. From a series of captive rearing experiments, Sho Tanaka reported that hatchling sharks grew in length by up to 0.77 mm (0.0303149606299213 in) per day. Males and females attain sexual maturity
at 86–96 cm (33.9–37.8 in) and 92–104 cm (36.2–40.9 in) long respectively; the growth rate after maturity is very low. Known parasites of this species include the nematode
Porrocaecum cephaloscyllii and the leech
Stibarobdella macrothela.
s. This species is caught incidentally
by Japanese and Taiwanese bottom trawlers and brought to market. Intensive commercial fishing
within its range do not yet appear to have impacted its numbers, but until more data are available the International Union for Conservation of Nature (IUCN) has listed it under 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 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, found at depths of 90–200 m (295.3–656.2 ft) 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 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...
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...
. It is benthic in nature and favors rocky reef
Reef
In nautical terminology, a reef is a rock, sandbar, or other feature lying beneath the surface of the water ....
s. Reaching 1.4 m (4.6 ft) in length, this thick-bodied shark has a broad head, large mouth, and two unequally-sized 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...
s positioned far back past the pelvic fins. It can be identified by its dorsal coloration, consisting of seven brown "saddles" and extensive darker mottling on a light tan background. This species has often been confounded with the draughtsboard shark
Draughtsboard shark
The draughtsboard shark is a species of catshark, family Scyliorhinidae, so named for its "checkerboard" color pattern of dark blotches. It is endemic to New Zealand, where it is also known as the carpet shark...
(C. isabellum) and the Sarawak pygmy swellshark (C. sarawakensis) in scientific literature
Scientific literature
Scientific literature comprises scientific publications that report original empirical and theoretical work in the natural and social sciences, and within a scientific field is often abbreviated as the literature. Academic publishing is the process of placing the results of one's research into the...
.
Voracious and opportunistic in feeding habits, the blotchy swell shark is known to consume numerous types of 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 and 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, including an unusually high diversity of cartilaginous fishes. Like other Cephaloscyllium species, it is capable of rapidly inflating its body as a defense against predators. This species is oviparous, with females laying encapsulated eggs two at a time. There is no well-defined breeding season
Breeding season
The breeding season is the most suitable season, usually with favourable conditions and abundant food and water, for breeding among some wild animals and birds . Species with a breeding season have naturally evolved to have sexual intercourse during a certain time of year in order to achieve the...
and reproduction occurs year-round. The eggs hatch after approximately one year. The blotchy swell shark is harmless and fares well in 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...
in 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...
bottom trawls, though its population does not seem to have suffered from fishing activity. The International Union for Conservation of Nature (IUCN) presently lacks sufficient information to assess its conservation status.
Taxonomy
American ichthyologists David Starr JordanDavid Starr Jordan
David Starr Jordan, Ph.D., LL.D. was a leading eugenicist, ichthyologist, educator and peace activist. He was president of Indiana University and Stanford University.-Early life and education:...
and Henry Weed Fowler
Henry Weed Fowler
Henry Weed Fowler was an American zoologist born in Holmesburg, Pennsylvania.He studied at Stanford University under David Starr Jordan...
described the blotchy swell shark in a 1903 volume of Proceedings of the United States National Museum, based on a 98 cm (38.6 in) long stuffed dry skin
Taxidermy
Taxidermy is the act of mounting or reproducing dead animals for display or for other sources of study. Taxidermy can be done on all vertebrate species of animals, including mammals, birds, fish, reptiles, and amphibians...
originally obtained from Nagasaki
Nagasaki
is the capital and the largest city of Nagasaki Prefecture on the island of Kyushu in Japan. Nagasaki was founded by the Portuguese in the second half of the 16th century on the site of a small fishing village, formerly part of Nishisonogi District...
, Japan. They gave it the specific epithet umbratile (from the 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...
umbratilis, meaning "shaded") and assigned it to the 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...
Cephaloscyllium.
The taxonomy
Taxonomy
Taxonomy is the science of identifying and naming species, and arranging them into a classification. The field of taxonomy, sometimes referred to as "biological taxonomy", revolves around the description and use of taxonomic units, known as taxa...
of the blotchy swell shark has a history of confusion. The holotype
Holotype
A holotype is a single physical example of an organism, known to have been used when the species was formally described. It is either the single such physical example or one of several such, but explicitly designated as the holotype...
dried skin could not be located when 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,...
perpared his 1979 review of the catsharks, and in its absence he synonymized C. umbratile with C. isabellum
Draughtsboard shark
The draughtsboard shark is a species of catshark, family Scyliorhinidae, so named for its "checkerboard" color pattern of dark blotches. It is endemic to New Zealand, where it is also known as the carpet shark...
on the basis of "inconclusive morphometric differences". Some authors followed Springer's judgment while others, particularly in Japan, preferred to keep referring to C. umbratile. The taxonomy of this species was further muddled by the application of the name C. umbratile to a similar but smaller species sharing part of its range. This second species, once referred to as "pseudo-umbratile" by Leonard Compagno
Leonard Compagno
Leonard Joseph Victor Compagno is an international authority on shark taxonomy and the author of many scientific papers and books on the subject, best known of which is his 1984 catalogue of shark species produced for the Food and Agriculture Organization of the United Nations.-Career:*Ph.D,...
, has since been identified as C. sarawakensis. Recently, the holotype was found again, and in 2008 Cephaloscyllium umbratile was re-described as distinct from C. isabellum by Jayna Schaaf-Da Silva and David Ebert.
Distribution and habitat
The blotchy swell shark is known to occur in 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...
from Hokkaido
Hokkaido
, formerly known as Ezo, Yezo, Yeso, or Yesso, is Japan's second largest island; it is also the largest and northernmost of Japan's 47 prefectural-level subdivisions. The Tsugaru Strait separates Hokkaido from Honshu, although the two islands are connected by the underwater railway Seikan Tunnel...
, 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...
southward 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 the Yellow Sea
Yellow Sea
The Yellow Sea is the name given to the northern part of the East China Sea, which is a marginal sea of the Pacific Ocean. It is located between mainland China and the Korean Peninsula. Its name comes from the sand particles from Gobi Desert sand storms that turn the surface of the water golden...
. Its range may extend as far as New Guinea
New Guinea
New Guinea is the world's second largest island, after Greenland, covering a land area of 786,000 km2. Located in the southwest Pacific Ocean, it lies geographically to the east of the Malay Archipelago, with which it is sometimes included as part of a greater Indo-Australian Archipelago...
. This abundant species is a bottom-dweller that inhabits rocky reef
Reef
In nautical terminology, a reef is a rock, sandbar, or other feature lying beneath the surface of the water ....
s on the 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,...
, at a depth of 90–200 m (295.3–656.2 ft).
Description
The maximum reported length of the blotchy swell shark is 1.4 m (4.6 ft). It has a firm, stout body with a soft, distensible abdomen, and a short, broad, flattened head. The snout is proportionately long and rounded, with large nostrils divided by short, triangular flaps of skin in front. The small, horizontally oval eyes are placed high on the head 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 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...
lies closely behind each eye. Behind the spiracle 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, which are short and become progressively smaller posteriorly. The capacious mouth forms a broad arch, and lacks furrows at the corners. The small teeth have a central cusp flanked by a smaller cusplet on both sides. There are around 59 tooth rows in the upper jaw and 62 tooth rows in the lower jaw.
The pectoral fins are moderately large and wide, with rounded tips. The 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...
s have rounded apexes and are placed well back on the body, the first originating behind the midpoints of the small pelvic fins. The first dorsal fin is about twice as high as the second. The anal fin is nearly as large as the first dorsal fin and placed slightly ahead of the second dorsal fin. The caudal fin is large and broad, with the upper lobe longer than the lower and bearing a prominent ventral notch near the tip. The skin is thick and sparsely covered by large, well-calcified
Calcification
Calcification is the process in which calcium salts build up in soft tissue, causing it to harden. Calcifications may be classified on whether there is mineral balance or not, and the location of the calcification.-Causes:...
dermal denticles; each denticle has a diamond-shaped crown with three horizontal ridges. This shark is cream-colored with dark brownish to grayish mottling on the back and sides, and seven dark brown dorsal "saddles" on the body and tail. The mottling intensifies with age, while the saddles fade and may become obscured. Older sharks may also have a dark blotch on either side between the pectoral and pelvic fins. The underside is pale, with scant darker marks.
Biology and ecology
Like other members of its genusGenus
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...
, when threatened the blotchy swell shark is capable of rapidly inflating its stomach
Stomach
The stomach is a muscular, hollow, dilated part of the alimentary canal which functions as an important organ of the digestive tract in some animals, including vertebrates, echinoderms, insects , and molluscs. It is involved in the second phase of digestion, following mastication .The stomach is...
with water or air. This allows the shark to wedge itself inside a rocky crevice, becoming extremely difficult to remove. This species is an opportunistic, highly voracious predator; one recorded female 1 m (3.3 ft) long had 10 fish about 20 cm (7.9 in) long and 15 squid about 15 cm (5.9 in) long in her stomach. Predominantly piscivorous, this species is known to prey upon hagfish
Hagfish
Hagfish, the clade Myxini , are eel-shaped slime-producing marine animals . They are the only living animals that have a skull but not a vertebral column. Along with lampreys, hagfish are jawless and are living fossils whose next nearest relatives include all vertebrates...
and at least 50 species of bony fishes, including fast-swimming types that inhabit open water; significant prey species include the mackerel
Mackerel
Mackerel is a common name applied to a number of different species of fish, mostly, but not exclusively, from the family Scombridae. They may be found in all tropical and temperate seas. Most live offshore in the oceanic environment but a few, like the Spanish mackerel , enter bays and can be...
Scomber japonicus, the sardine
Sardine
Sardines, or pilchards, are several types of small, oily fish related to herrings, family Clupeidae. Sardines are named after the Mediterranean island of Sardinia, around which they were once abundant....
Sardinops melanostictus, the filefish
Filefish
Filefish are tropical to subtropical tetraodontiform marine fish of the diverse family Monacanthidae. Found in the Atlantic, Pacific and Indian Oceans, the filefish family contains approximately 107 species in 26 genera...
Thamnaconus modestus, and the hakeling
Moridae
Moridae is a family of cod-like fishes, known as codlings, hakelings, and moras.Morids are marine fishes found throughout the world, and may be found at depths of up to , although most prefer shallower waters...
Physiculus japonicus. Unusually for such a small shark, it also feeds on at least 10 species of cartilaginous fishes, including lantern shark
Etmopteridae
Etmopteridae 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. The members of this family are small, under long, and are found in deep waters worldwide. There are 45 species in five...
s, 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....
s (particularly the cloudy catshark
Cloudy catshark
The cloudy catshark is a common species of catshark, family Scyliorhinidae. It is a bottom-dweller that inhabits rocky reefs in the northwestern Pacific Ocean, from the shore to a depth of...
, Scyliorhinus torazame, and its eggs), the electric ray
Electric ray
The electric rays are a group of rays, flattened cartilaginous fish with enlarged pectoral fins, comprising the order Torpediniformes. They are known for being capable of producing an electric discharge, ranging from as little as 8 volts up to 220 volts depending on species, used to stun prey and...
Narke japonica, and skate
Skate
Skates are cartilaginous fish belonging to the family Rajidae in the superorder Batoidea of rays. There are more than 200 described species in 27 genera. There are two subfamilies, Rajinae and Arhynchobatinae ....
s (including their eggs). It also cannibalizes
Cannibalism (zoology)
In zoology, cannibalism is the act of one individual of a species consuming all or part of another individual of the same species as food. Cannibalism is a common ecological interaction in the animal kingdom and has been recorded for more than 1500 species...
smaller members of its own species. 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, mostly the squid
Squid
Squid are cephalopods of the order Teuthida, which comprises around 300 species. Like all other cephalopods, squid have a distinct head, bilateral symmetry, a mantle, and arms. Squid, like cuttlefish, have eight arms arranged in pairs and two, usually longer, tentacles...
Doryteuthis bleekeri and the cuttlefish
Cuttlefish
Cuttlefish are marine animals of the order Sepiida. They belong to the class Cephalopoda . Despite their name, cuttlefish are not fish but molluscs....
Sepia
Sepia (genus)
Sepia is a genus of cuttlefish in the family Sepiidae encompassing some of the best known and most common species. The cuttlebone is relatively ellipsoid in shape...
spp., are also frequently taken, while 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, 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 isopods are occasionally consumed. The dietary composition of juveniles varies notably from place to place.
The blotchy swell shark is oviparous, and reproduction proceeds throughout the year with no obvious seasonal cycling. 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. The species is thought to be relatively prolific, as the ovary contains numerous ova
Ovum
An ovum is a haploid female reproductive cell or gamete. Both animals and embryophytes have ova. The term ovule is used for the young ovum of an animal, as well as the plant structure that carries the female gametophyte and egg cell and develops into a seed after fertilization...
at various stages of development. Pairs of eggs are laid at a time, one per oviduct. Females have been documented producing eggs even after years without male contact, suggesting that they may be able to store sperm
Sperm
The term sperm is derived from the Greek word sperma and refers to the male reproductive cells. In the types of sexual reproduction known as anisogamy and oogamy, there is a marked difference in the size of the gametes with the smaller one being termed the "male" or sperm cell...
. The purse-shaped egg capsules are relatively large and thick, measuring around 12 cm (4.7 in) long and 7 cm (2.8 in) across. The capsule surface is smooth with lengthwise striations, and opaque cream in color with yellow margins. Long, coiled tendrils extend from the four corners of the capsule. When the 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...
is 11 cm (4.3 in) long, the external gills
External gills
External gills are the gills of an animal, most typically an amphibian, that are exposed to the environment, rather than set inside the pharynx and covered by gill slits, as they are in most fishes. Instead, the respiratory organs are set on a frill of stalks protruding from the sides of an animals...
have been lost, the dermal denticles have begun to develop, and light brown saddles are present. The eggs take roughly one year to hatch; newly emerged sharks measure 16–22 cm (6.3–8.7 in) long. From a series of captive rearing experiments, Sho Tanaka reported that hatchling sharks grew in length by up to 0.77 mm (0.0303149606299213 in) per day. Males and females attain sexual maturity
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 86–96 cm (33.9–37.8 in) and 92–104 cm (36.2–40.9 in) long respectively; the growth rate after maturity is very low. Known parasites of this species include the nematode
Nematode
The nematodes or roundworms are the most diverse phylum of pseudocoelomates, and one of the most diverse of all animals. Nematode species are very difficult to distinguish; over 28,000 have been described, of which over 16,000 are parasitic. It has been estimated that the total number of nematode...
Porrocaecum cephaloscyllii and 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.
Human interactions
Harmless to humans, the blotchy swell shark adapts readily to captivity and has reproduced 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. This species 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 Japanese and Taiwanese bottom trawlers and brought to market. Intensive commercial fishing
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...
within its range do not yet appear to have impacted its numbers, but until more data are available the International Union for Conservation of Nature (IUCN) has listed it under 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...
.