The Triton epaulette shark (''Hemiscyllium henryi'') is a

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

of bamboo shark in the genus ''

Hemiscyllium ''Hemiscyllium'' is a genus of sharks in the family Hemiscylliidae. Overview Hemiscyllium sharks of the family Hemiscylliidae are also known as walking sharks and Epaulette sharks. These small, nocturnal, benthic dwelling swimmers have evo ...

'', that is composed of nine morphologically similar, yet distinct, sharks that are geographically restricted to

New Guinea New Guinea (; Hiri Motu: ''Niu Gini''; , fossilized , also known as Papua or historically ) is the List of islands by area, world's second-largest island, with an area of . Located in Melanesia in the southwestern Pacific Ocean, the island is ...

and northern

Australia Australia, officially the Commonwealth of Australia, is a country comprising mainland Australia, the mainland of the Australia (continent), Australian continent, the island of Tasmania and list of islands of Australia, numerous smaller isl ...

. Hemiscylliidae are small nocturnal sharks aptly named "walking sharks" who exhibit a "crawling" movement while foraging on the ocean floor for fish and

benthic The benthic zone is the ecological region at the lowest level of a body of water such as an ocean, lake, or stream, including the sediment surface and some sub-surface layers. The name comes from the Ancient Greek word (), meaning "the depths". ...

invertebrates.Allen, G.R., Erdmann, M.V., White, W.T., Fahmi & Dudgeon, C.L. (2016) Review of the bamboo shark genus Hemiscyllium (Orectolobiformes: Hemiscyllidae). Journal of the Ocean Science Foundation, 23, 51–97.

Morphology

Indonesia Maluku-Western New Guinea topography location map

These small slender sharks are characterized by nasoral and perioral grooves, short barbels, a small transverse mouth below the eyes, two similar-sized dorsal fins and long slender tail. They are typically pale gray-brown with a white

ventral Standard anatomical terms of location are used to describe unambiguously the anatomy of humans and other animals. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position prov ...

surface. Individuals of the genus ''Hemiscyllium henryi'' are distinguished by their unique colour pattern of a combination of small scattered spots on the head, body, and fins with 13 to 18 spots on the interorbital/dorsal snout region and 6-28 spots on the dorsal surface of their pectoral fins. ''Hemiscyllium henryi'' have an irregular shaped

ocellus A simple eye or ocellus (sometimes called a pigment pit) is a form of eye or an optical arrangement which has a single lens without the sort of elaborate retina that occurs in most vertebrates. These eyes are called "simple" to distinguish the ...

(typically a merged double-ocellus), surrounded by a poorly defined white halo marking in the middle of their side just behind their head. The lack of small dark spots on their dorsal fins sets them apart from other ''Hemiscylliidae''. The males and the unsexed sharks grow to an average of 78.3 cm in length. The females grow to an average of 81.5 cm in length. In three preserved specimens collected in the Triton Bay region, the number of vertebrae was found to range from 191 to 194.Allen, G., Erdmann, M.V., White, Dudgeon, C.L., (2013). ''Hemiscyllium halmahera'', A New Species of Bamboo Shark (Hemiscyllidae) From Indonesia. Aqua, International Journal of Ichthyology, 126.

Reproduction

Hemiscyllium species are

oviparous Oviparous animals are animals that reproduce by depositing fertilized zygotes outside the body (i.e., by laying or spawning) in metabolically independent incubation organs known as eggs, which nurture the embryo into moving offsprings kno ...

, benthic reproducers. They deposit their eggs on or near the sea bed.

Sexual dimorphism

Male hemiscyllids have paired

claspers In biology, a clasper is a male anatomical structure found in some groups of animals, used in mating. Male cartilaginous fish have claspers formed from the posterior portion of their pelvic fin which serve to channel semen into the female's c ...

that are used to grasp the female during copulation. These distinctive organs vary in size within the species although insufficient data due to small sample sizes have not been found to show a variation in claspers between species. Until the onset of maturation, juvenile sharks possess small underdeveloped claspers. Enlargement occurs rapidly as intermediate sizes have not yet been observed. Mature males have an inner clasper length of 6.7–11.9% TL and outer clasper length of 5.5–9.5% TL (n=17). Immature males have an inner clasper length of 2.8–4.5% TL and an outer clasper length of 0.9-2.0% TL (n=13).

Habitat and ecology

Hemiscyllium henryi are marine,

reef A reef is a ridge or shoal of rock, coral, or similar relatively stable material lying beneath the surface of a natural body of water. Many reefs result from natural, abiotic component, abiotic (non-living) processes such as deposition (geol ...

-associated sharks that are typically found on coral reefs, rubble, or seagrass flats. The depth range where they are typically found is 3 - 30m showcasing an ability to remain in shallow water as well as swim to substantial depths. Their observed climate zone is tropical. ''Hemiscyllium henryi'' can mostly be seen resting during the day as they are nocturnal and are occasionally observed slowly swimming or 'walking' with their pectoral and

pelvic fins Pelvic fins or ventral fins are paired fins located on the ventral (belly) surface of fish, and are the lower of the only two sets of paired fins (the other being the laterally positioned pectoral fins). The pelvic fins are homologous to the hi ...

in search for food or shelter. ''Hemiscyllids'' primarily consume crustaceans, cephalopods, shelled mollusks, and small bottom fish found along the sea floor and sheltered in table coral or other rocky features.

Etymology

The shark is named in honor of underwater photographer Wolcott Henry, who has supported Conservation International's marine initiatives, which includes the taxonomy of western New Guinea fishes.

Distribution

''H. henryi'' have been observed and collected from western New Guinea (West Papua Province, Indonesia) in the southern Bird's Head region. They were also observed at Triton Bay and Selat Iris, a narrow channel between the mainland and Aiduma Island and near the southwestern tip of the

Bomberai Peninsula Bomberai Peninsula () is located in the Western New Guinea region. It is south of the Bird's Head Peninsula, and Bintuni Bay separates the two peninsulas. To the west lies the Sebakor Bay and to the south Kamrau Bay. On the southeast Arguni ...

- 135 km west of Triton Bay. Further surveys may show that ''H. Henryi'' have a broader range in southern West Papua.

Conservation status

This species was recently described in 2008 and their conservation status is listed as vulnerable by the IUCN. Due to their limited range ''H. henryi'' would be extremely susceptible to depletion should attempts be made to harvest them for trade or food.

Relationship with humans

Bamboo sharks are not dangerous to humans. Additionally, bamboo sharks are one of the few species of sharks kept in home aquariums.Michael, Scott. “Aquarium Fish: The Epaulette Sharks( Hemiscyllium Spp.) – The Perfect Aquarium Sharks.” Reefs.com. 20 July 2020. reefs.com/magazine/aquarium-fish-the-epaulette-sharks-hemiscyllium-spp-the-perfect-aquarium-sharks/. Accessed 2 Nov. 2020.

References

External links

* Michael, S. (May 13, 2008).
New Epaulette Walking Sharks!
' Retrieved August 30, 2011. {{Taxonbar, from=Q28843 henryi Fish of Western New Guinea Taxa named by Gerald R. Allen Taxa named by Mark van Nydeck Erdmann Fish described in 2008