Haploblepharus
Encyclopedia
Haploblepharus is a genus
of catshark
, family
Scyliorhinidae, containing four species
of shysharks. Their common name
comes from a distinctive defensive behavior in which the shark curls into a circle and covers its eyes with its tail. The genus is endemic to southern Africa
, inhabiting shallow coastal waters. All four species are small, stout-bodied sharks with broad, flattened heads and rounded snouts. They are characterized by very large nostril
s with enlarged, triangular flaps of skin that reach the mouth, and deep grooves between the nostrils and the mouth. Shysharks are bottom-dwelling predators of bony fishes and invertebrate
s. They are oviparous, with the females laying egg capsule
s. These harmless sharks are of no commercial
or recreational
interest, though their highly limited distributions in heavily fished South African waters are of potential conservation concern.
, then known as Squalus edwardsii. The name is derived from the Greek haplóos meaning "single", and blepharos meaning "eyelid".
In 1988, Leonard Compagno
placed Haploblepharus with Halaelurus
and Holohalaelurus
in the tribe Halaelurini of the family Scyliorhinidae, based on morphological
characters. This interpretation was corroborated by a 2006 phylogenetic analysis
based on three mitochondrial DNA
gene
s. However, that study also found that within this group Haploblepharus is most closely related to the genus Halaelurus, which is inconsistent with the presence of three autapomorphic traits
in Haploblepharus that are not shared by either Halaelurus or Holohalaelurus. Within the genus, the puffadder shyshark is the most basal
species.
; three of them are found only off South Africa
, while the range of the dark shyshark extends to southern Namibia
. They are bottom-dwelling in nature and usually found in shallow, coastal waters over sandy or rocky bottoms.
Different shyshark species are very similar to one another in appearance but can be reliably differentiated using morphological measurements. However, in the field the only way to readily tell them apart is by their different color patterns, and even this may be problematic as individuals of the same species can vary considerably in coloration. All four species are small, seldom exceeding 60 cm (23.6 in) in length.
A shyshark has a stout, spindle-shaped body and a short head comprising less than one-fifth of the total length. The head is broad and dorsally flattened, with a rounded snout. The large, oval eyes have cat-like slit pupil
s, a rudimentary nictitating membrane
(protective third eyelid
), and a prominent ridge running underneath. A distinguishing trait of this genus are the large nostril
s partially covered by greatly expanded, triangular flaps of skin that overlap the mouth and cover a pair of deep grooves between the nasal excurrent (outflow) openings and the mouth. The mouth is short and curved, with furrows at the corners extending onto both jaws. The teeth have a central cusp and smaller lateral cusplets. The five pairs of gill slit
s are located on the upper side of the body.
The two dorsal fin
s are set far back on the body, the first originating behind the pelvic fin midbases and the second originating behind the anal fin midbase. The pectoral fins are moderately large; the dorsal, pelvic, and anal fins are of similar size. The broad caudal fin comprises a fifth of the total length; the upper lobe has a deep vental notch near the tip and the lower lobe is virtually absent. The skin is thick and covered by well-calcified
, leaf-shaped dermal denticles. The coloration is brown above and white below; the brown shyshark is usually plain while the other species have varying patterns of darker "saddles" and white spots.
Shysharks feed on a variety of small benthic bony fishes and invertebrate
s. In turn, they are preyed upon by larger fishes and marine mammal
s. When threatened, these sharks adopt a curious posture in which they curl their bodies into a ring and cover their eyes with their tails, which is the origin of the name "shyshark". This behavior likely serves to make the shark more difficult for a predator to swallow. Shysharks are oviparous with females producing egg capsules (known as "mermaid's purse
s") two at a time. Reproduction has been investigated in the puffadder and dark shysharks; neither species appears to have a distinct breeding season
, and their eggs take around three and a half weeks to hatch.
or recreational fishers
. They are taken as bycatch
and hooked by shore anglers, who regard them (and other catsharks) as minor pests. Although shysharks are not uncommon, their extremely limited distribution within heavily fished waters raises concerns that a local increase in fishing pressure or habitat degradation could affect entire species populations. As a result, the International Union for Conservation of Nature (IUCN) has assessed two shyshark species as Near Threatened
.
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...
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, containing four species
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 shysharks. Their common name
Common name
A common name of a taxon or organism is a name in general use within a community; it is often contrasted with the scientific name for the same organism...
comes from a distinctive defensive behavior in which the shark curls into a circle and covers its eyes with its tail. The genus is endemic to southern Africa
Southern Africa
Southern Africa is the southernmost region of the African continent, variably defined by geography or geopolitics. Within the region are numerous territories, including the Republic of South Africa ; nowadays, the simpler term South Africa is generally reserved for the country in English.-UN...
, inhabiting shallow coastal waters. All four species are small, stout-bodied sharks with broad, flattened heads and rounded snouts. They are characterized by very large 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 with enlarged, triangular flaps of skin that reach the mouth, and deep grooves between the nostrils and the mouth. Shysharks are bottom-dwelling predators of bony fishes 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. They are oviparous, with the females laying egg capsule
Mermaid's purse
An egg case or egg capsule, colloquially known as a mermaid's purse or devil's purse, is a casing that surrounds the fertilized eggs of some sharks, skates, and chimaeras. They are among the common objects which are washed up by the sea. They are made of collagen protein strands...
s. These harmless sharks are of no 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...
or recreational
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....
interest, though their highly limited distributions in heavily fished South African waters are of potential conservation concern.
Taxonomy and phylogeny
The genus Haploblepharus was created by American zoologist Samuel Garman in 1913, in the 36th volume of Memoirs of the Museum of Comparative Zoology, at Harvard College, to contain the puffadder shysharkPuffadder shyshark
The puffadder shyshark or happy Eddie is a species of catshark, family Scyliorhinidae, endemic to the temperate waters off South Africa. This common shark is found on or near the bottom in sandy or rocky habitats, from the intertidal zone to a depth of . Typically reaching in length, the...
, then known as Squalus edwardsii. The name is derived from the Greek haplóos meaning "single", and blepharos meaning "eyelid".
In 1988, 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,...
placed Haploblepharus with Halaelurus
Halaelurus
Halaelurus is a genus of catshark in the family Scyliorhinidae.-Species:* Halaelurus boesemani S. Springer & D'Aubrey, 1972 * Halaelurus buergeri...
and Holohalaelurus
Holohalaelurus
Holohalaelurus is a genus of catshark in the family Scyliorhinidae, commonly known as Izak catsharks or hallelujah sharks.-Species:* Holohalaelurus favus Human, 2006...
in the tribe Halaelurini of the family Scyliorhinidae, 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....
characters. This interpretation was corroborated by a 2006 phylogenetic analysis
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...
based on three mitochondrial DNA
Mitochondrial DNA
Mitochondrial DNA is the DNA located in organelles called mitochondria, structures within eukaryotic cells that convert the chemical energy from food into a form that cells can use, adenosine triphosphate...
gene
Gene
A gene is a molecular unit of heredity of a living organism. It is a name given to some stretches of DNA and RNA that code for a type of protein or for an RNA chain that has a function in the organism. Living beings depend on genes, as they specify all proteins and functional RNA chains...
s. However, that study also found that within this group Haploblepharus is most closely related to the genus Halaelurus, which is inconsistent with the presence of three autapomorphic traits
Autapomorphy
In cladistics, an autapomorphy is a distinctive anatomical feature, known as a derived trait, that is unique to a given terminal group. That is, it is found only in one member of a clade, but not found in any others or outgroup taxa, not even those most closely related to the group...
in Haploblepharus that are not shared by either Halaelurus or Holohalaelurus. Within the genus, the puffadder shyshark is the most basal
Basal (phylogenetics)
In phylogenetics, a basal clade is the earliest clade to branch in a larger clade; it appears at the base of a cladogram.A basal group forms an outgroup to the rest of the clade, such as in the following example:...
species.
Species
- Haploblepharus edwardsii (SchinzHeinrich Rudolf SchinzHeinrich Rudolf Schinz was a Swiss physician and naturalist.Schinz was born at Zurich and studied medicine at Würzburg and Jena, returning to Zurich in 1798 to practice...
, 1822) (Puffadder shyshark) - Haploblepharus fuscus J. L. B. Smith, 1950 (Brown shyshark)
- Haploblepharus kistnasamyi Human & Compagno, 2006 (Natal shyshark)
- Haploblepharus pictus (J. P. MüllerJohannes Peter MüllerJohannes Peter Müller , was a German physiologist, comparative anatomist, and ichthyologist not only known for his discoveries but also for his ability to synthesize knowledge.-Early years and education:...
& HenleFriedrich Gustav Jakob HenleFriedrich Gustav Jakob Henle was a German physician, pathologist and anatomist. He is credited with the discovery of the loop of Henle in the kidney. His essay "On Miasma and Contagia" was an early argument for the germ theory of disease...
, 1838) (Dark shyshark)
Distribution and habitat
All four shyshark species are endemic to the southern tip of AfricaSouthern Africa
Southern Africa is the southernmost region of the African continent, variably defined by geography or geopolitics. Within the region are numerous territories, including the Republic of South Africa ; nowadays, the simpler term South Africa is generally reserved for the country in English.-UN...
; three of them are found only off South Africa
South Africa
The Republic of South Africa is a country in southern Africa. Located at the southern tip of Africa, it is divided into nine provinces, with of coastline on the Atlantic and Indian oceans...
, while the range of the dark shyshark extends to southern Namibia
Namibia
Namibia, officially the Republic of Namibia , is a country in southern Africa whose western border is the Atlantic Ocean. It shares land borders with Angola and Zambia to the north, Botswana to the east and South Africa to the south and east. It gained independence from South Africa on 21 March...
. They are bottom-dwelling in nature and usually found in shallow, coastal waters over sandy or rocky bottoms.
Description
A shyshark has a stout, spindle-shaped body and a short head comprising less than one-fifth of the total length. The head is broad and dorsally flattened, with a rounded snout. The large, oval eyes have cat-like slit pupil
Pupil
The pupil is a hole located in the center of the iris of the eye that allows light to enter the retina. It appears black because most of the light entering the pupil is absorbed by the tissues inside the eye. In humans the pupil is round, but other species, such as some cats, have slit pupils. In...
s, a 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...
(protective third eyelid
Eyelid
An eyelid is a thin fold of skin that covers and protects an eye. With the exception of the prepuce and the labia minora, it has the thinnest skin of the whole body. The levator palpebrae superioris muscle retracts the eyelid to "open" the eye. This can be either voluntarily or involuntarily...
), and a prominent ridge running underneath. A distinguishing trait of this genus are the large 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 partially covered by greatly expanded, triangular flaps of skin that overlap the mouth and cover a pair of deep grooves between the nasal excurrent (outflow) openings and the mouth. The mouth is short and curved, with furrows at the corners extending onto both jaws. The teeth have a central cusp and smaller lateral cusplets. 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 located on the upper side of the body.
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 set far back on the body, the first originating behind the pelvic fin midbases and the second originating behind the anal fin midbase. The pectoral fins are moderately large; the dorsal, pelvic, and anal fins are of similar size. The broad caudal fin comprises a fifth of the total length; the upper lobe has a deep vental notch near the tip and the lower lobe is virtually absent. The skin is thick and covered by 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:...
, leaf-shaped dermal denticles. The coloration is brown above and white below; the brown shyshark is usually plain while the other species have varying patterns of darker "saddles" and white spots.
Biology and ecology
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. In turn, they are preyed upon by larger fishes and marine mammal
Marine mammal
Marine mammals, which include seals, whales, dolphins, and walruses, form a diverse group of 128 species that rely on the ocean for their existence. They do not represent a distinct biological grouping, but rather are unified by their reliance on the marine environment for feeding. The level of...
s. When threatened, these sharks adopt a curious posture in which they curl their bodies into a ring and cover their eyes with their tails, which is the origin of the name "shyshark". This behavior likely serves to make the shark more difficult for a predator to swallow. Shysharks are oviparous with females producing egg capsules (known as "mermaid's purse
Mermaid's purse
An egg case or egg capsule, colloquially known as a mermaid's purse or devil's purse, is a casing that surrounds the fertilized eggs of some sharks, skates, and chimaeras. They are among the common objects which are washed up by the sea. They are made of collagen protein strands...
s") two at a time. Reproduction has been investigated in the puffadder and dark shysharks; neither species appears to have a distinct 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 their eggs take around three and a half weeks to hatch.
Human interactions
Due to their small size, shysharks pose no danger to humans and are not sought by either commercialCommercial 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...
or recreational fishers
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....
. They are taken 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...
and hooked by shore anglers, who regard them (and other catsharks) as minor pests. Although shysharks are not uncommon, their extremely limited distribution within heavily fished waters raises concerns that a local increase in fishing pressure or habitat degradation could affect entire species populations. As a result, the International Union for Conservation of Nature (IUCN) has assessed two shyshark species 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...
.