| Puffadder shyshark | |
|---|---|
 | |
Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Chondrichthyes |
| Subclass: | Elasmobranchii |
| Division: | Selachii |
| Order: | Carcharhiniformes |
| Family: | Pentanchidae |
| Genus: | Haploblepharus |
| Species: | H. edwardsii |
| Binomial name | |
| Haploblepharus edwardsii (Schinz, 1822) | |
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| Range of the puffadder shyshark | |
| Synonyms | |
Scyllium edwardsiiSchinz, 1822 | |
Thepuffadder shyshark (Haploblepharus edwardsii), also known as theHappy Eddie, is a species ofshark belonging to thefamilyPentanchidae, the deepwater catsharks. This species isendemic to thetemperate waters off the coast ofSouth Africa. This common shark is found on or near the bottom in sandy or rockyhabitats, from theintertidal zone to a depth of 130 m (430 ft). Typically reaching 60 cm (24 in) in length, the puffadder shyshark has a slender, flattened body and head. It is strikingly patterned with a series of dark-edged, bright orange "saddles" and numerous small white spots over its back. TheNatal shyshark (H. kistnasamyi), formally described in 2006, was once considered to be an alternate form of the puffadder shyshark.
When threatened, the puffadder shyshark (and other members of its genus) curls into a circle with its tail covering its eyes, giving rise to the local names "shyshark" and "doughnut". It is apredator that feeds mainly oncrustaceans,polychaete worms, and smallbony fishes. This shark isoviparous and females deposit egg capsules singly or in pairs onto underwater structures. Harmless to humans, the puffadder shyshark is usually discarded bycommercial andrecreational fishers alike for its small size. It has been assessed as endangered by theInternational Union for Conservation of Nature (IUCN), as its entire population is located within a limited area and could be affected by a local increase in fishing pressure orhabitat degradation.
The first known reference to the puffadder shyshark in literature was by prominent English naturalistGeorge Edwards in 1760, by the nameCatulus major vulgaris,[2] of three individuals caught off theCape of Good Hope that have since been lost. In 1817, French zoologistGeorges Cuvier described this species as "Scyllium D'Edwards", based on Edwards' account, though he was not considered to be proposing a truescientific name. In 1832, German zoologist Friedrich Siegmund Voigt translated Cuvier's description under the nameScyllium edwardsii, thus receiving attribution for the species. However, in 2001 M.J.P. van Oijen discovered that Swiss naturalistHeinrich Rudolf Schinz had provided an earlier translation of Cuvier's text with the proper scientific name in 1822, and subsequently theInternational Commission on Zoological Nomenclature (ICZN) rendered a decision that this species is properly attributed to Schinz.[3][4][5] In 1913, American zoologistSamuel Garman created the new genusHaploblepharus for this and other shyshark species.[6]
Twoforms of puffadder shyshark were once recognized: "Cape" and "Natal", which differed in appearance and habitat preferences. In 2006, the "Natal" form was described as a new species, theNatal shyshark.[7] A 2006phylogenetic analysis, based on threemitochondrial DNAgenes, found that the puffadder shyshark is the mostbasal member of its family, with a sister relationship to theclade containing thedark shyshark (H. pictus) and thebrown shyshark (H. fuscus). The Natal shyshark was not included in the study, though it is very closemorphologically to this species.[8] Thecommon name "puffadder shyshark" refers to thepuff adder (Bitis arietans), a widely distributed Africanviper with similar coloration.[9] "Happy Eddie" (from the scientific nameHaploblepharus edwardsii) is used by academics for this shark, and was recently introduced to the public as an easily remembered alternative to the ambiguous vernaculars "shyshark" and "doughnut", which can apply to several different species and have confounded research efforts.[5]
The puffadder shyshark is more slender than other shysharks, with a short, broad, dorsally flattened head and a narrowly rounded snout.[5] The large, oval-shaped eyes have cat-like slitpupils, a simplenictitating membrane (a protective thirdeyelid), and a prominent ridge underneath. Thenostrils are very large, with a pair of greatly expanded, triangular flaps of skin in front that are fused together and reach the mouth. There is a deep groove connecting the excurrent (outflow) opening of each nostril to the mouth, obscured by the nasal flaps. The mouth is short with furrows at the corners on both jaws.[6] There are 26–30 tooth rows in the upper jaw and 27–33 tooth rows in the lower jaw. Tooth shape issexually dimorphic: those of males are longer and three-pointed, while those of females are shorter and five-pointed.[10] Unusually, the two halves of the lower jaw are connected by a specialcartilage, which allows a more even distribution of teeth and may increase bite strength.[11]
The five pairs ofgill slits are positioned somewhat on the upper surface of the body. Thedorsal,pelvic, andanal fins are all of similar size. The dorsal fins are located far back on the body, the first originating behind the pelvic fin origins and the second behind the anal fin origin. Thepectoral fins are broad and of moderate size. The short, broadcaudal fin comprises about one-fifth of the body length and has a deep ventral notch near the tip of the upper lobe and a barely developed lower lobe. The skin is thick and covered by well-calcified, leaf-shapeddermal denticles.[6] The dorsal coloration consists of a light to dark brown background with a series of 8–10 striking yellowish to reddish brown "saddles" with darker margins, all covered by a profusion of small white spots. The underside is white. This species attains a length of 60 cm (24 in), with a maximum record of 69 cm (27 in).[12] Sharks found west ofCape Agulhas are smaller than those found east, reaching only 48 cm (19 in) long.[5]
The range of the puffadder shyshark is limited to thecontinental shelf along the coast ofSouth Africa, fromLangebaan Lagoon inWestern Cape Province to the western shore ofAlgoa Bay. Previous records of it being found as far north asDurban are now thought to be misidentifications of other species.[5] Thisbottom-dwelling shark is most common over sandy or rocky bottoms. It is found in progressively deeper water towards the northeastern portion of its range, from 0–15 m (0–49 ft) offCape Town to 40–130 m (130–430 ft) offKwaZulu-Natal; this distribution pattern may reflect this shark's preference for cooler waters.[6]
Quite common within its small range, the sluggish and reclusive puffadder shyshark is often seen lying still on the sea floor.[9][13] It is gregarious and several individuals may rest together.[12] A generalistpredator with graspingdentition, the puffadder shyshark is known to take a variety of smallbenthic prey:crustaceans (includingcrabs,shrimp,crayfish,mantis shrimp, andhermit crabs),annelid worms (includingpolychaetes),bony fishes (includinganchovies,jack mackerels, andgobies),cephalopods (includingsquid), and fishoffal.[10] Overall, the most important component of this shark's diet is crustaceans, followed by polychaetes and then fishes. Males seem to prefer polychaetes, while females prefer crustaceans.[12][14] It has been observed attacking acommon octopus (Octopus vulgaris) by tearing off an arm with a twisting motion.[15]
The puffadder shyshark is preyed upon by larger fishes, such as thebroadnose sevengill shark (Notorynchus cepedianus).[16] TheCape fur seal (Arctocephalus pusillus pusillus) has been documented capturing and playing with puffadder shysharks, tossing them into the air or gnawing on them. The shark is often injured or killed during these encounters; the seal may eat torn-off pieces of flesh, but seldom consumes the entire shark. On occasion,black-backed kelp gulls (Larus dominicanus vetula) take advantage of this behavior and steal the sharks from the seals.[17] When threatened or disturbed, the puffadder shyshark adopts a characteristic posture in which it curls into a ring and covers its eyes with its tail; this reaction is the basis for the common names "shyshark" and "doughnut", and is likely meant to make the shark harder for a predator to swallow.[5][12]
The eggs of the puffadder shyshark are fed upon by thewhelksBurnupena papyracea andB. lagenaria, at least in captivity.[18] Knownparasites of this species include thetrypanosomeTrypanosoma haploblephari, which infests theblood,[19] thenematodeProleptus obtusus, which infests theintestine,[20] and thecopepodsCharopinus dalmanni andPerissopus oblongatus, which infest the skin.[21] Another parasite is the pranizalarval stage of theisopodGnathia pantherina, which infests thenares, mouth, and gills. The deep-penetrating mouthparts of these larvae significantly damage local tissue, causing bleeding andinflammation.[22]
The puffadder shyshark isoviparous; there is no distinctbreeding season and reproduction occurs year-round.[14] Females depositegg capsules one or two at a time, attaching them to vertical structures such assea fans.[12] The thin-walled egg cases are brown with distinctive pale transverse bands; and have a slightly furry texture and long adhesive tendrils at the corners. They are smaller than those of other shyshark species, measuring 3.5–5 cm (1.4–2.0 in) long and 1.5–3 cm (0.59–1.18 in) across.[11][23] The young shark hatches after three months, and measures around 9 cm (3.5 in) long.[1] The length atmaturation for both sexes has been reported as anywhere from 35 to 55 cm (14 to 22 in) by various sources; this high degree of variation may reflect regional differences as sharks from deeper waters in the eastern part of its range seem to mature at a larger size than those from the west.[5] The age at maturation is estimated to be around 7 years, and themaximum lifespan is at least 22 years.[14]
Harmless to humans, the puffadder shyshark can be easily caught by hand.[24] Not targeted bycommercial fisheries because of its small size, it istaken incidentally and discarded bybottom trawlers operating betweenMossel Bay andEast London, and by fishing boats inFalse Bay. Many are hooked byrecreational anglers casting from the shore, who also generally discard or kill them as minor pests.[11] Some local exploitation of this species does occur forlobster bait and theaquarium trade. TheInternational Union for Conservation of Nature (IUCN) has assessed the puffadder shyshark as endangered. The small range of this shark lies entirely within a heavily fished region, and any increase in fishing activities orhabitat degradation could potentially impact the entire population.[24]
Media related toHaploblepharus edwardsii at Wikimedia Commons