Striped catshark
Encyclopedia
The pyjama shark or striped catshark (Poroderma africanum) is a species
of catshark
, family
Scyliorhinidae, endemic to the coastal waters of South Africa. This abundant, bottom-dwelling species can be found from the intertidal zone
to a depth of around 100 m (328.1 ft), particularly over rocky reef
s and kelp
beds. With a series of thick, parallel, dark stripes running along its stout body, the pyjama shark has an unmistakable appearance. It is additionally characterized by a short head and snout with a pair of slender barbels
that do not reach the mouth, and two dorsal fin
s that are placed far back on the body. It grows up to 1.1 m (3.6 ft) long.
The primarily nocturnal pyjama shark spends most of the day lying motionless, hidden in a cave or crevice or among vegetation. It often forms groups, particularly during summer. This species is an opportunistic predator that feeds on a wide variety of fish
es and invertebrate
s; it favors cephalopod
s and frequents the spawning grounds of the chokka squid
(Loligo vulgaris reynaudi). When threatened, it curls into a circle with its tail covering its head. Reproduction is oviparous, with females laying rectangular, dark brown egg cases two at a time year-round. This small and harmless shark adapts well to captivity and is commonly displayed in public aquarium
s. It is often caught as a bycatch
of commercial
and recreational fisheries
. Many are killed by fishers who regard them as pests. Although there are no data suggesting its numbers have declined, the International Union for Conservation of Nature (IUCN) has assessed the pyjama shark as Near Threatened
because of expanding small shark fishery activities within its limited range.
Johann Friedrich Gmelin
in 1789, in the thirteenth edition of Systema Naturae
. He did not designate a type specimen. In 1837, Scottish physician and zoologist Andrew Smith
created the new genus Poroderma for this species and the related leopard catshark
(P. pantherinum, at the time believed to be multiple species). In 1908, the pyjama shark was made the type species
of the genus by American zoologist Henry Weed Fowler
.
inshore waters, the pyjama shark is found off South Africa, from Table Bay
off Cape Town
to north of East London. It is most abundant off the Western Cape
, and may venture as far as Saldanha Bay
in the west and KwaZulu-Natal
in the east; old records from Mauritius, Madagascar, and Zaire are almost certainly erroneous. The pyjama shark is commonly encountered in very shallow intertidal
and littoral waters no more than 5 m (16.4 ft) deep, though in and around Algoa Bay
it occurs at depths of 50–100 m (164–328.1 ft) and has been reported to 108 m (354.3 ft). It favors rocky reef
s and beds of Ecklonia
kelp
.
species, growing to 1.1 m (3.6 ft) long and 7.9 kg (17.4 lb) or more in weight. Both sexes grow to roughly the same maximum size. The head and snout are short and slightly flattened, with a narrowly parabolic outline when viewed from above or below. Each nostril is split into tiny incurrent and excurrent openings by a flap of skin in front; the flap has a three-lobed shape with the central lobe forming a long, conical barbel
. The barbels are thicker than in the leopard catshark, and do not reach the mouth. The eyes are horizontally oval and placed rather high on the head, with rudimentary nictitating membrane
s (protective third eyelids) and a thick ridge running underneath. The sizable mouth forms a broad arch, with short furrows extending from the corners onto both the upper and lower jaws; the upper teeth are exposed when the mouth is closed. There are 18–25 and 14–24 tooth rows on either side of the upper and lower jaws, respectively. The teeth have a slender central cusp flanked by a pair of small cusplets; those of adult males are slightly thicker than those of females.
The body is fairly compressed from side to side and tapers towards the tail. The two dorsal fin
s are placed far back: the first originates over the rear of the pelvic fins while the second originates over the midpoint of the anal fin. The first dorsal is much larger than the second. The pectoral fins are large and broad. The pelvic fins are lower than the pectorals but their bases are about equal in length. Adult males have a pair of short, thick claspers, with the inner margins of the pelvic fins partially fused over them to form an "apron". The short and broad caudal fin has an indistinct lower lobe and a ventral notch near the tip of the upper lobe. The skin is very thick and bears well-calcified
dermal denticles; each denticle has an arrowhead-shaped crown with three posterior points, mounted on a short stalk. The dorsal coloration is distinctive, consisting of 5–7 thick, parallel, dark stripes running from the snout to the caudal peduncle on a variably grayish or brownish background; the stripes become broken near the tail and the belly. In some sharks, the main stripe on either side may fork behind the eye, the stripes may be split in two by lighter central lines, or one or more large dark spots may be present. The underside is pale, sometimes with light gray spotting, and clearly demarcated from the flank color. Young sharks resemble the adults, but may be much lighter or have much darker stripes. An albino specimen has been recorded from False Bay
.
(Notorynchus cepedianus). When threatened, it often curls into a circle with its tail covering its head, in a similar fashion to the shysharks (Haploblepharus). Its eggs are fed upon by the whelks
Burnupena papyracea
and B. lagenaria
, which can pierce the outer covering to extract the yolk within. Like other sharks, the pyjama shark maintains osmotic balance
with the environment by regulating its internal concentration of urea
and other nitrogenous wastes. Experiments have shown that the shark's capacity for osmoregulation is dependent on how well it has fed.
The pyjama shark feeds on a wide variety of small animals, including bony fishes such as anchovies, gurnard
s, and hakes, hagfish
es, smaller sharks and rays
and their egg cases, crustacean
s, cephalopod
s, bivalves, and polychaete worms; it has also been known to scavenge
on fish offal
. Although it has a predilection for cephalopods, the dietary composition of this opportunistic predator generally reflects the locally available prey types. For example, in False Bay the Cape rock lobster
(Jasus lalandii) is the most important food source, followed by cephalopods and then fish. Pyjama sharks have been observed seizing and tearing off tentacles from octopus
and cuttlefish
with a twisting motion; on one occasion three sharks were seen attacking an octopus simultaneously in this manner. During mass spawnings of the chokka squid
(Loligo vulgaris reynaudi), which occur unpredictably year-round but peak from October to December, pyjama sharks deviate from their nocturnal habits and gather in substantial numbers inside the squids' "egg beds" during daytime. The sharks conceal their heads amongst the egg masses, while their stripes break up the outlines of their bodies. As the female squid descend to the sea floor to attach their eggs, guarded by the males, they become vulnerable to the sharks' ambush attacks.
An oviparous species, both male and female pyjama sharks seem to be reproductively active throughout the year. Adult females have a single functional ovary
and two functional oviduct
s, with a single egg maturing in each at a time. The egg is contained in a tough, rectangular, dark brown capsule 9.5 cm (3.7 in) long and 4.5 cm (1.8 in) across, with long tendrils at the corners that enable the female to fasten the capsule to underwater structures such as algae
stipe
s or gorgonians. Eggs maintained in aquariums hatch in approximately five and a half months, with the hatching shark measuring 14–15 cm (5.5–5.9 in) long. Males and females begin to mature sexually
at 78–81 cm (30.7–31.9 in) and 79–83 cm (31.1–32.7 in) long respectively, and all sharks are adult by a length of 89 cm (35 in).
s. The aquarium trade supports a small fishery targeting this species and the similar leopard catshark. Large numbers of pyjama sharks are caught incidentally
by commercial fisheries using longlines, gillnet
s, beach-seines, and bottom trawls; they are also readily hooked by recreational anglers
, especially during the summer when they aggregate. Although edible, most are discarded while some are used for lobster bait. The toll taken by fishery bycatch
is likely greatly underestimated, as many fishers who use line gear regard pajama sharks as pests that "steal" bait, and kill them before discarding them.
The International Union for Conservation of Nature (IUCN) has listed the pyjama shark as Near Threatened
, citing its small distribution and a recent increase in fishing pressure on small sharks in the region. However, there is no evidence to suggest that its population has declined. There are no specific conservation measures in place for this species, though its range encompasses two marine reserves. The South African Sea Fisheries Research Institute is considering legally decommercializing the pyjama shark, which would limit the degree to which it can be targeted by commercial fisheries.
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, endemic to the coastal waters of South Africa. This abundant, bottom-dwelling species can be found from the intertidal zone
Intertidal zone
The intertidal zone is the area that is above water at low tide and under water at high tide . This area can include many different types of habitats, with many types of animals like starfish, sea urchins, and some species of coral...
to a depth of around 100 m (328.1 ft), particularly over rocky reef
Reef
In nautical terminology, a reef is a rock, sandbar, or other feature lying beneath the surface of the water ....
s and kelp
Kelp
Kelps are large seaweeds belonging to the brown algae in the order Laminariales. There are about 30 different genera....
beds. With a series of thick, parallel, dark stripes running along its stout body, the pyjama shark has an unmistakable appearance. It is additionally characterized by a short head and snout with a pair of slender barbels
Barbel (anatomy)
A barbel on a fish is a slender, whiskerlike tactile organ near the mouth. Fish that have barbels include the catfish, the carp, the goatfish, sturgeon, the zebrafish and some species of shark...
that do not reach the mouth, and two 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 that are placed far back on the body. It grows up to 1.1 m (3.6 ft) long.
The primarily nocturnal pyjama shark spends most of the day lying motionless, hidden in a cave or crevice or among vegetation. It often forms groups, particularly during summer. This species is an opportunistic predator that feeds on a wide variety 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; it favors 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 and frequents the spawning grounds of the chokka squid
Loligo vulgaris reynaudi
Loligo reynaudii, commonly known as the Cape Hope Squid, is a large squid belonging to the family Loliginidae. In South Africa it is known as either calamari or chokka....
(Loligo vulgaris reynaudi). When threatened, it curls into a circle with its tail covering its head. Reproduction is oviparous, with females laying rectangular, dark brown egg cases two at a time year-round. This small and harmless shark adapts well to captivity and is commonly displayed in public aquarium
Public 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. It is often caught as a 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...
of 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...
and recreational fisheries
Recreational fishing
Recreational fishing, also called sport fishing, is fishing for pleasure or competition. It can be contrasted with commercial fishing, which is fishing for profit, or subsistence fishing, which is fishing for survival....
. Many are killed by fishers who regard them as pests. Although there are no data suggesting its numbers have declined, the International Union for Conservation of Nature (IUCN) has assessed the pyjama shark as Near Threatened
Near Threatened
Near Threatened is a conservation status assigned to species or lower taxa that may be considered threatened with extinction in the near future, although it does not currently qualify for the threatened status...
because of expanding small shark fishery activities within its limited range.
Taxonomy
The pyjama shark was originally described as Squalus africanus by German naturalistNaturalist
Naturalist may refer to:* Practitioner of natural history* Conservationist* Advocate of naturalism * Naturalist , autobiography-See also:* The American Naturalist, periodical* Naturalism...
Johann Friedrich Gmelin
Johann Friedrich Gmelin
Johann Friedrich Gmelin was a German naturalist, botanist, entomologist, herpetologist and malacologist.- Education :Johann Friedrich Gmelin was born as the eldest son of Philipp Friedrich Gmelin in 1748 in Tübingen...
in 1789, in the thirteenth edition of Systema Naturae
Systema Naturae
The book was one of the major works of the Swedish botanist, zoologist and physician Carolus Linnaeus. The first edition was published in 1735...
. He did not designate a type specimen. In 1837, Scottish physician and zoologist Andrew Smith
Andrew Smith (zoologist)
Sir Andrew Smith KCB was a Scottish surgeon, explorer, ethnologist and zoologist. He is considered the father of Zoology in South Africa having described many species across a wide range of groups in his major work, Illustrations of the Zoology of South Africa.Smith was born in Hawick, Roxburghshire...
created the new genus Poroderma for this species and the related leopard catshark
Leopard catshark
The leopard catshark is a species of catshark, family Scyliorhinidae, endemic to the coastal waters of South Africa. Abundant in inshore waters under deep, this bottom-dweller favors rocky reefs, kelp beds, and sandy flats. Growing to a length of , the leopard catshark has a stout body with two...
(P. pantherinum, at the time believed to be multiple species). In 1908, the pyjama shark was made the type species
Type species
In biological nomenclature, a type species is both a concept and a practical system which is used in the classification and nomenclature of animals and plants. The value of a "type species" lies in the fact that it makes clear what is meant by a particular genus name. A type species is the species...
of the genus by American zoologist 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...
.
Distribution and habitat
A bottom-dwelling inhabitant of temperateTemperate
In geography, temperate or tepid latitudes of the globe lie between the tropics and the polar circles. The changes in these regions between summer and winter are generally relatively moderate, rather than extreme hot or cold...
inshore waters, the pyjama shark is found off South Africa, from Table Bay
Table Bay
Table Bay is a natural bay on the Atlantic Ocean overlooked by Cape Town and is at the northern end of the Cape Peninsula, which stretches south to the Cape of Good Hope. It was named because it is dominated by the flat-topped Table Mountain.Bartolomeu Dias was the first European to explore this...
off Cape Town
Cape Town
Cape Town is the second-most populous city in South Africa, and the provincial capital and primate city of the Western Cape. As the seat of the National Parliament, it is also the legislative capital of the country. It forms part of the City of Cape Town metropolitan municipality...
to north of East London. It is most abundant off the Western Cape
Western Cape
The Western Cape is a province in the south west of South Africa. The capital is Cape Town. Prior to 1994, the region that now forms the Western Cape was part of the much larger Cape Province...
, and may venture as far as Saldanha Bay
Saldanha Bay
Saldanha Bay is a natural harbour on the south-western coast of South Africa, north west of Cape Town. The town that developed on the northern shore of the bay, also called Saldanha, was incorporated with five other towns into the Saldanha Bay Local Municipality in 2000. The current population of...
in the west and KwaZulu-Natal
KwaZulu-Natal
KwaZulu-Natal is a province of South Africa. Prior to 1994, the territory now known as KwaZulu-Natal was made up of the province of Natal and the homeland of KwaZulu....
in the east; old records from Mauritius, Madagascar, and Zaire are almost certainly erroneous. The pyjama shark is commonly encountered in very shallow intertidal
Intertidal zone
The intertidal zone is the area that is above water at low tide and under water at high tide . This area can include many different types of habitats, with many types of animals like starfish, sea urchins, and some species of coral...
and littoral waters no more than 5 m (16.4 ft) deep, though in and around Algoa Bay
Algoa Bay
Algoa Bay is a wide inlet along the South African east coast, some 425 miles east of the Cape of Good Hope. It is bounded in the west by Cape Recife and in the east by Cape Padrone. The bay is up to 436 m deep...
it occurs at depths of 50–100 m (164–328.1 ft) and has been reported to 108 m (354.3 ft). It favors rocky reef
Reef
In nautical terminology, a reef is a rock, sandbar, or other feature lying beneath the surface of the water ....
s and beds of Ecklonia
Ecklonia
Ecklonia is a genus of kelp belonging to the family Lessoniaceae.There are nine species:* Ecklonia biruncinata* Ecklonia brevipes* Ecklonia cava* Ecklonia fastigiata* Ecklonia kurome* Ecklonia maxima* Ecklonia muratii...
kelp
Kelp
Kelps are large seaweeds belonging to the brown algae in the order Laminariales. There are about 30 different genera....
.
Description
The pyjama shark is the larger and thicker-bodied of the two PorodermaPoroderma
Poroderma is a genus of catshark, family Scyliorhinidae. The colour of these sharks are usually grey with dark stripes. They are found in South Africa and are nocturnal. They live preferably in shore areas, close to the bottom, to depths of 100 m. They prefer small caves and crevices. Their diet...
species, growing to 1.1 m (3.6 ft) long and 7.9 kg (17.4 lb) or more in weight. Both sexes grow to roughly the same maximum size. The head and snout are short and slightly flattened, with a narrowly parabolic outline when viewed from above or below. Each nostril is split into tiny incurrent and excurrent openings by a flap of skin in front; the flap has a three-lobed shape with the central lobe forming a long, conical barbel
Barbel (anatomy)
A barbel on a fish is a slender, whiskerlike tactile organ near the mouth. Fish that have barbels include the catfish, the carp, the goatfish, sturgeon, the zebrafish and some species of shark...
. The barbels are thicker than in the leopard catshark, and do not reach the mouth. The eyes are horizontally oval and placed rather high on the head, with rudimentary nictitating membrane
Nictitating membrane
The nictitating membrane is a transparent or translucent third eyelid present in some animals that can be drawn across the eye for protection and to moisten it while maintaining visibility. Some reptiles, birds, and sharks have a full nictitating membrane; in many mammals, there is a small...
s (protective third eyelids) and a thick ridge running underneath. The sizable mouth forms a broad arch, with short furrows extending from the corners onto both the upper and lower jaws; the upper teeth are exposed when the mouth is closed. There are 18–25 and 14–24 tooth rows on either side of the upper and lower jaws, respectively. The teeth have a slender central cusp flanked by a pair of small cusplets; those of adult males are slightly thicker than those of females.
The body is fairly compressed from side to side and tapers towards the tail. The two 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 are placed far back: the first originates over the rear of the pelvic fins while the second originates over the midpoint of the anal fin. The first dorsal is much larger than the second. The pectoral fins are large and broad. The pelvic fins are lower than the pectorals but their bases are about equal in length. Adult males have a pair of short, thick claspers, with the inner margins of the pelvic fins partially fused over them to form an "apron". The short and broad caudal fin has an indistinct lower lobe and a ventral notch near the tip of the upper lobe. The skin is very thick and bears 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 an arrowhead-shaped crown with three posterior points, mounted on a short stalk. The dorsal coloration is distinctive, consisting of 5–7 thick, parallel, dark stripes running from the snout to the caudal peduncle on a variably grayish or brownish background; the stripes become broken near the tail and the belly. In some sharks, the main stripe on either side may fork behind the eye, the stripes may be split in two by lighter central lines, or one or more large dark spots may be present. The underside is pale, sometimes with light gray spotting, and clearly demarcated from the flank color. Young sharks resemble the adults, but may be much lighter or have much darker stripes. An albino specimen has been recorded from False Bay
False Bay
False Bay is a body of water defined by Cape Hangklip and the Cape Peninsula in the extreme South-West of South Africa.- Description and location :...
.
Biology and ecology
Rather slow-swimming, the pyjama shark spends most of the day resting in caves or crevices or amongst kelp, emerging at night to actively forage for food. Many individuals may congregate at a single spot, particularly in summer. This species falls prey to larger sharks, and is one of the cartilaginous fish most frequently consumed by the broadnose sevengill sharkBroadnose sevengill shark
The broadnose sevengill shark is the only extant member of the genus Notorynchus, in the family Hexanchidae. It is recognizable because of its seven gill slits, while most shark species have five gill slits, with the exception of the members of the order Hexanchiformes and the sixgill sawshark.The...
(Notorynchus cepedianus). When threatened, it often curls into a circle with its tail covering its head, in a similar fashion to the shysharks (Haploblepharus). Its eggs are fed upon by the whelks
Buccinidae
Buccinidae is a very large and diverse taxonomic family of large sea snails, often known as whelks or true whelks.True whelks are mostly marine gastropod mollusks in the clade Neogastropoda...
Burnupena papyracea
Burnupena papyracea
Burnupena papyracea, common name the papery burnupena, is a species of sea snail, a marine gastropod mollusk in the family Buccinidae, the true whelks....
and B. lagenaria
Burnupena lagenaria
Burnupena lagenaria is a species of sea snail, a marine gastropod mollusk in the family Buccinidae, the true whelks....
, which can pierce the outer covering to extract the yolk within. Like other sharks, the pyjama shark maintains osmotic balance
Osmoregulation
Osmoregulation is the active regulation of the osmotic pressure of an organism's fluids to maintain the homeostasis of the organism's water content; that is it keeps the organism's fluids from becoming too diluted or too concentrated. Osmotic pressure is a measure of the tendency of water to move...
with the environment by regulating its internal concentration of urea
Urea
Urea or carbamide is an organic compound with the chemical formula CO2. The molecule has two —NH2 groups joined by a carbonyl functional group....
and other nitrogenous wastes. Experiments have shown that the shark's capacity for osmoregulation is dependent on how well it has fed.
The pyjama shark feeds on a wide variety of small animals, including bony fishes such as anchovies, gurnard
Sea robin
Sea robins, also known as gurnard, are bottom-feeding scorpaeniform fishes in the family Triglidae. They get their name from their large pectoral fins, which, when swimming, open and close like a bird's wings in flight....
s, and hakes, 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...
es, smaller sharks and rays
Elasmobranchii
Elasmobranchii is a subclass of Chondrichthyes or cartilaginous fish, that includes the sharks and the rays and skates .-Evolution:...
and their egg cases, 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, 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, bivalves, and polychaete worms; it has also been known to scavenge
Scavenger
Scavenging is both a carnivorous and herbivorous feeding behavior in which individual scavengers search out dead animal and dead plant biomass on which to feed. The eating of carrion from the same species is referred to as cannibalism. Scavengers play an important role in the ecosystem by...
on fish offal
Offal
Offal , also called, especially in the United States, variety meats or organ meats, refers to the internal organs and entrails of a butchered animal. The word does not refer to a particular list of edible organs, which varies by culture and region, but includes most internal organs other than...
. Although it has a predilection for cephalopods, the dietary composition of this opportunistic predator generally reflects the locally available prey types. For example, in False Bay the Cape rock lobster
Jasus lalandii
Jasus lalandii is a species of spiny lobster found off the coast of Southern Africa. It is not known whom the specific epithet lalandii commemorates, although it may be the French astronomer Jérôme Lalande.J...
(Jasus lalandii) is the most important food source, followed by cephalopods and then fish. Pyjama sharks have been observed seizing and tearing off tentacles from octopus
Octopus
The octopus is a cephalopod mollusc of the order Octopoda. Octopuses have two eyes and four pairs of arms, and like other cephalopods they are bilaterally symmetric. An octopus has a hard beak, with its mouth at the center point of the arms...
and 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....
with a twisting motion; on one occasion three sharks were seen attacking an octopus simultaneously in this manner. During mass spawnings of the chokka squid
Loligo vulgaris reynaudi
Loligo reynaudii, commonly known as the Cape Hope Squid, is a large squid belonging to the family Loliginidae. In South Africa it is known as either calamari or chokka....
(Loligo vulgaris reynaudi), which occur unpredictably year-round but peak from October to December, pyjama sharks deviate from their nocturnal habits and gather in substantial numbers inside the squids' "egg beds" during daytime. The sharks conceal their heads amongst the egg masses, while their stripes break up the outlines of their bodies. As the female squid descend to the sea floor to attach their eggs, guarded by the males, they become vulnerable to the sharks' ambush attacks.
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...
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, with a single egg maturing in each at a time. The egg is contained in a tough, rectangular, dark brown capsule 9.5 cm (3.7 in) long and 4.5 cm (1.8 in) across, with long tendrils at the corners that enable the female to fasten the capsule to underwater structures such as algae
Algae
Algae are a large and diverse group of simple, typically autotrophic organisms, ranging from unicellular to multicellular forms, such as the giant kelps that grow to 65 meters in length. They are photosynthetic like plants, and "simple" because their tissues are not organized into the many...
stipe
Stipe (botany)
In botany, a stipe is a stalk that supports some other structure. The precise meaning is different depending on which taxonomic group is being described....
s or gorgonians. Eggs maintained in aquariums hatch in approximately five and a half months, with the hatching shark measuring 14–15 cm (5.5–5.9 in) long. Males and females begin to mature sexually
Sexual maturity
Sexual maturity is the age or stage when an organism can reproduce. It is sometimes considered synonymous with adulthood, though the two are distinct...
at 78–81 cm (30.7–31.9 in) and 79–83 cm (31.1–32.7 in) long respectively, and all sharks are adult by a length of 89 cm (35 in).
Human interactions
Among the most common South African catsharks, the pyjama shark is harmless to humans and difficult to approach underwater. Because of its small size, attractive appearance, and hardiness, it is popularly exhibited by 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. The aquarium trade supports a small fishery targeting this species and the similar leopard catshark. Large numbers of pyjama sharks are 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 fisheries using longlines, gillnet
Gillnet
Gillnetting is a common fishing method used by commercial and artisanal fishermen of all the oceans and in some freshwater and estuary areas. The gillnet also is used by fisheries scientists to monitor fish populations. Because gillnets can be so effective their use is closely monitored and...
s, beach-seines, and bottom trawls; they are also readily hooked by recreational anglers
Recreational fishing
Recreational fishing, also called sport fishing, is fishing for pleasure or competition. It can be contrasted with commercial fishing, which is fishing for profit, or subsistence fishing, which is fishing for survival....
, especially during the summer when they aggregate. Although edible, most are discarded while some are used for lobster bait. The toll taken by fishery 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...
is likely greatly underestimated, as many fishers who use line gear regard pajama sharks as pests that "steal" bait, and kill them before discarding them.
The International Union for Conservation of Nature (IUCN) has listed the pyjama shark as Near Threatened
Near Threatened
Near Threatened is a conservation status assigned to species or lower taxa that may be considered threatened with extinction in the near future, although it does not currently qualify for the threatened status...
, citing its small distribution and a recent increase in fishing pressure on small sharks in the region. However, there is no evidence to suggest that its population has declined. There are no specific conservation measures in place for this species, though its range encompasses two marine reserves. The South African Sea Fisheries Research Institute is considering legally decommercializing the pyjama shark, which would limit the degree to which it can be targeted by commercial fisheries.