The leopard epaulette shark (''Hemiscyllium michaeli''), also known as the Milne Bay epaulette shark and Michael's epaulette shark, is a species of

bamboo shark The Hemiscylliidae are a family (biology), family of sharks in the order Orectolobiformes, commonly known as longtail carpet sharks and sometimes as bamboo sharks. They are found in shallow waters of the tropical Indo-Pacific. They are relativ ...

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 ...

''.''Hemiscyllium michaeli''
at www.fishbase.org. It is a

tropical The tropics are the regions of Earth surrounding the equator, where the sun may shine directly overhead. This contrasts with the temperate or polar regions of Earth, where the Sun can never be directly overhead. This is because of Earth's ax ...

shark known from the shallow ocean in the

Milne Bay Milne Bay is a large bay in Milne Bay Province, south-eastern Papua New Guinea. More than long and over wide, Milne Bay is a sheltered deep-water harbor accessible via Ward Hunt Strait. It is surrounded by the heavily wooded Stirling Range (Papu ...

region of eastern

Papua New Guinea Papua New Guinea, officially the Independent State of Papua New Guinea, is an island country in Oceania that comprises the eastern half of the island of New Guinea and offshore islands in Melanesia, a region of the southwestern Pacific Ocean n ...

. The epaulette sharks of this region have long been confused with the

Indonesian speckled carpetshark The Indonesian speckled carpetshark, ''Hemiscyllium freycineti'', is a species of bamboo shark in the family Hemiscylliidae. It is found in the shallow ocean around the Raja Ampat Islands in West Papua, Indonesia, but was formerly believed to be ...

(''H. freycineti''), and it was only in 2010 that ''H. michaeli'' was described as a separate species by Gerald R. Allen and Christine L. Dudgeon.Gerald R. Allen and Christine L. Dudgeon (2010): ''Hemiscyllium michaeli'', a new species of Bamboo Shark (Hemiscyllidae) from Papua New Guinea, pp. 19-30. ''Aqua International Journal of Ichthyology'' 16 (1) It can reach a maximum length of 82 cm (32.3 in). Confusingly, some books with illustrations and photos labelled as ''H. freycineti'' actually show ''H. michaeli''.

Etymology

The leopard epaulette shark was originally confused with the Indonesian speckled carpetshark, until photographer and aquarist Scott W. Michael recognized that they were distinct species and brought this to the attention of researchers. The shark was subsequently named in honour of Michael, and for his contributions of information and photographs to Allen's research on Indo-Pacific fishes. Another common name for this species is the Milne Bay epaulette shark. In the paper by Allen and Dudgeon, it is said that the two populations are geographically separated by approximately 1,200 km.

Distribution and habitat

The range of the leopard epaulette shark is confined to eastern

, with most observations and collecting records from the

province. It has also been collected at

Oro Province Oro Province, formerly (and officially still) Northern Province, is a coastal Provinces of Papua New Guinea, province in the Southern Region, Papua New Guinea, Southern Region of Papua New Guinea. The provincial capital is Popondetta. The provinc ...

in the vicinity of Harvey Bay. It is unclear if the distribution of the leopard epaulette shark extends along the

mainland northwest towards

Bootless Inlet Bootless Inlet or Bootless Bay is a body of water in south-eastern Papua New Guinea, approximately southeast of Port Moresby. There are four islands in the bay: Motupore Island, Loloata Island, Manunouha Island, and Bunamotu Island. A barrier ...

, nor where its distribution abuts that of the Papuan epaulette shark (''Hemiscyllium hallstromi''). The presence of ''

'' in the

Huon Gulf Huon Gulf is a large gulf in eastern Papua New Guinea. It is bordered by Huon Peninsula in the north. Both are named after French explorer Jean-Michel Huon de Kermadec. Huon Gulf is a part of the Solomon Sea. Its northern boundary is marke ...

is unknown; presumably the large estuarine area around

Lae Lae (, , later ) is the capital of Morobe Province and is the second-largest city in Papua New Guinea. It is located near the delta of the Markham River on the northern coast of Huon Gulf. It is at the start of the Highlands Highway, which is ...

may provide sufficient habitat disjunction to separate ''H. michaeli'' and the Hooded epaulette shark (''Hemiscyllium strahani''). The leopard epaulette shark is found in shallow water to a maximum depth of 20 m (66 ft) in fringing and patch tropical coral reefs, rocky outcrops, tidal pools, and seagrass beds.

Description

The leopard epaulette shark has an elongated body, over half of which is comprised by the slender caudal peduncle. Its

dorsal fin A dorsal fin is a fin on the back of most marine and freshwater vertebrates. Dorsal fins have evolved independently several times through convergent evolution adapting to marine environments, so the fins are not all homologous. They are found ...

and

anal fin Fins are moving appendages protruding from the body of fish that interact with water to generate thrust and help the fish swim. Apart from the tail or caudal fin, fish fins have no direct connection with the back bone and are supported o ...

is set very far back on an extremely long, thick tail. It differs from other ''

'' species by having a shorter first

and

base, and lower

. The eyes are oval in shape and elevated, with a large spiracle below each. The five pairs of

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 and rays, as well as deep-branching vertebrates such as lampreys. In c ...

s are small, with the fourth and fifth very close together. Leopard Epaulette Shark juvenile

This species of ''

'' is characterized by its unique colour pattern, which includes dense leopard-like spotting covering the body and a noticeable large black ocellated spot behind the head. It is similar in appearance to '' H. freycineti'' but can be differentiated by having denser and more leopard-like dark spots, a larger and well-developed post-cephalic ocellus, and a greater number of spots on the snout's dorsal surface. The overall coloration is whitish to pale grey-brown, with a dense network of leopard-like brown spots on the head, body, and fins. There is a distinct white-rimmed dark-brown mark behind the head, roughly aligned with the posterior edge of the pectoral fin. Sometimes, a series of about 9-10 bars may be faintly visible on the sides and more prominent on the tail. The dorsal fins feature 2–3 prominent saddle-like markings along their edges. Subadults of this species lack leopard-like spots and instead have solid spots on their head, body, and fins. Juveniles of this species display a predominantly white coloration with a number of dark brown bars, including on the head and caudal fin. There are a few small brown spots on the head and anterior body, situated within pale areas. Despite being partially merged with the second dark bar, the distinct large ocellus characteristic of the species is still evident. The snout is short and rounded, with the nares placed almost at the tip along with a pair of tiny

barbels In fish anatomy and turtle anatomy, a barbel is a slender, whisker like sensory organ near the mouth (sometimes called whiskers or tendrils). Fish that have barbels include the catfish, the carp, the goatfish, the hagfish, the sturgeon, the z ...

; there are grooves running from the nares to the mouth. There are possibly 26–35 tooth rows in the upper jaw and 21–32 tooth rows in the lower jaw. The teeth are small, with broad bases and triangular cusps. Leopard epaulette sharks are typically 60–78 cm (23.6–30.7 in) long; the maximum reported length is at least 82 cm (32.3 in).

Biology and ecology

Although this species is critically understudied, we still know that as an

adaptation In biology, adaptation has three related meanings. Firstly, it is the dynamic evolutionary process of natural selection that fits organisms to their environment, enhancing their evolutionary fitness. Secondly, it is a state reached by the p ...

for navigating its complex reef environment, like other members of the ''

'' genus'','' the leopard epaulette shark moves by seemingly walking, bending its body from side-to-side and pushing off of the substrate with its paddle-shaped pectoral and pelvic fins. Its gait is similar to that of

salamander Salamanders are a group of amphibians typically characterized by their lizard-like appearance, with slender bodies, blunt snouts, short limbs projecting at right angles to the body, and the presence of a tail in both larvae and adults. All t ...

s, an example of

convergent evolution Convergent evolution is the independent evolution of similar features in species of different periods or epochs in time. Convergent evolution creates analogous structures that have similar form or function but were not present in the last comm ...

. The shark is capable of swimming, but often prefers to walk along the sandy or coral bottom even when the water is deep enough to allow it to swim freely. The

cartilaginous Cartilage is a resilient and smooth type of connective tissue. Semi-transparent and non-porous, it is usually covered by a tough and fibrous membrane called perichondrium. In tetrapods, it covers and protects the ends of long bones at the joints ...

supports of the shark's paired fins are reduced and separated when compared to other sharks, allowing them to be rotated for use as limbs. This mode of locomotion even enables the shark to crawl out of the water to access isolated tidal pools. The gait of the epaulette shark is convergently similar to those of

tetrapod A tetrapod (; from Ancient Greek :wiktionary:τετρα-#Ancient Greek, τετρα- ''(tetra-)'' 'four' and :wiktionary:πούς#Ancient Greek, πούς ''(poús)'' 'foot') is any four-Limb (anatomy), limbed vertebrate animal of the clade Tetr ...

s such as

s, suggesting that the movements needed for walking on land may predate, and facilitated the evolution of, the first terrestrial

vertebrate Vertebrates () are animals with a vertebral column (backbone or spine), and a cranium, or skull. The vertebral column surrounds and protects the spinal cord, while the cranium protects the brain. The vertebrates make up the subphylum Vertebra ...

s.Martin, R.A
Intertidal Zone: Epaulette Shark
. ReefQuest Centre for Shark Research. Retrieved on May 14, 2009. Leopard epaulette sharks are largely

nocturnal Nocturnality is a ethology, behavior in some non-human animals characterized by being active during the night and sleeping during the day. The common adjective is "nocturnal", versus diurnality, diurnal meaning the opposite. Nocturnal creatur ...

and are most active in low water. They often hide inside or below coral heads, though it is enough for the head to be covered even if the rest of the body is exposed. Sometimes they perch in the open on sandy flats or atop reefs facing into the current, a form of orientation known as rheotaxis that may improve

respiration Respiration may refer to: Biology * Cellular respiration, the process in which nutrients are converted into useful energy in a cell ** Anaerobic respiration, cellular respiration without oxygen ** Maintenance respiration, the amount of cellul ...

or predator awareness. The first-ever footage of a leopard epaulette shark leaving the water and walking on land was captured by wildlife biologist and rare species expert

Forrest Galante Forrest Galante (born March 31, 1988) is an American outdoor adventurer and television personality. He primarily seeks out animals on the brink of extinction. He is the host of the television shows ''Extinct or Alive'' on Animal Planet and "Myste ...

. The footage was shown as part of a documentary called '' Island of the Walking Sharks'', co-hosted by fellow marine biologist Vicky Vásquez. The documentary was released as part of

Shark Week Shark Week is an annual week-long programming block on the Discovery Channel focusing on shark-themed programming. It originally premiered on July 17, 1988. The block is featured annually in the summer, and was originally devoted to conservati ...

2022. The footage was the first time in history one of the Papuan species of Epaulette had been recorded and filmed walking out of the water. The documentary further focused on the other two Papuan epaulettes, the Papuan epaulette shark and the hooded epaulette shark.

Comparisons

Due to the similarity of colour pattern and a misunderstanding of the geographic range, this species was long confused with '' H. freycineti.'' Due to sub-adults and some adults not developing the full leopard pattern, the species can also be confused with ''H. hallstromi''. In a blog post, Scott W. Michael postulated that "two new species" of the leopard epaulette shark could be present "off the coast of Milne Bay Province." He compared an observation by Rob van der Loos off a resort in

with an observation he had made 100 km southeast. He suggested that the differences in coloration, particularly the epaulette over the pectoral fin, could give rise to the possibility of there being two epaulette species off the coast of Milne Bay Province, and speculates that the observed differences in colouration may be attributed to the age of the shark specimen. He further added that while colour differences may not always be a reliable indicator for distinguishing fish species, it appears to be a consistent characteristic for differentiating members within the ''

'' genus. He further proposed that further investigation involving shark DNA analysis by Dr. Allen and the passage of time will provide more conclusive information.

Human interactions

Leopard epaulette sharks are harmless to humans, though if handled they may nip their captors. Due to their restricted range, they experience habitat degradation, and capture for food in artisanal fisheries. They could possibly enter the aquarium trade.

References

{{Taxonbar, from=Q28711 Hemiscyllium Fish of Papua New Guinea Taxa named by Gerald R. Allen Taxa named by Christine L. Dudgeon Fish described in 2010