EPAULETTE SHARK OR EPAULETTE CARPETSHARK
A shark that can walk on land
The Epaulette shark or also known as the Epaulette carpetshark (Hemiscyllium ocellatum) is a species of shark belonging to the family Hemiscylliidae, found in shallow, tropical waters off Australia and New Guinea (and possibly other locations as well). The common name of this shark comes from the very large, white-margined black spot behind each pectoral fin, which resemble military epaulettes. Adults are light brown above, with scattered darker spots and indistinct saddles. Epaulette sharks are nocturnal, and they have evolved to cope with sever oxygen depletion, or hypoxia in tidal pools. They do this by increasing the blood supply to its brain and selectively shutting down non-essential neural functions.
Family: Hemiscylliidae – Longtail Carpetsharks
Common Name– Carpet Sharks
Average Size and Length: Hatchlings measure around 15 cm/ 5.9 inches. Mature males have been measured between 59-62 cm/ 1.9-2 feet. Mature females have been measured at 64 cm/ 2.1 feet. The longest recorded was 107 cm/ 3.5 feet. An egg case measures 10 cm/ 3.9 inches long and 4 cm/ 1.6 inches wide.
Current Rare Mythical Sightings: The Epaulette shark was originally described as Squalus ocellatus by the French naturalist Pierre Joseph Bonnaterre in the 1788 Tableau encyclopédique et méthodique des trois règnes de la nature. The name was later changed to the currently valid Hemiscyllium ocellatum. The type specimen was a 35 cm/ 14 inches long immature male caught near Cooktown, Queensland, Australia.
In 2015, the behavior of an Epaulette shark was filmed in detail by the BBC for the first episode of a new documentary series named Shark, released around the 40th anniversary of Jaws.
Teeth and Jaw: The upper and lower teeth are somewhat stout and wide at the bottom, coming to a straight, sharp point. There are 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.
Head: The snout is short and rounded, with the nares placed almost at the tip along with a pair of tiny barbels. There are grooves running from the nares to the mouth. The eyes are oval in shape and elevated, with a large spiracle below each.
Tail: The tail is extremely long and thick. The caudal fin has only an upper lobe, which contains a prominent ventral notch near the tip and is angled almost horizontally relative to the body.
Demographic, Distribution, Habitat, Environment and Range: The Epaulette shark or Epaulette carpetshark can be found in the southwest Pacific Ocean in New Guinea and Australia (1°S – 34°S, 112°E – 163°E). The Capricorn-Bunker Group of the Great Barrier Reef has one of the largest populations. Thousands are estimated to inhabit the reefs around Heron Island alone. They may also be found in the Solomon Islands and Malaysia, but this isn’t confirmed. They can be found in coral, particularly staghorn coral, in shallow water and in tidepools. They are sometimes barely submerged because they have a high tolerance to hypoxia and low oxygenated environments. They have been found from the surface t a maximum depth of 160 feet. They prefer tropical climates.
Diet: They mainly eat worms, crustaceans and small fish.
Larger sharks and larger fish may prey upon them.
Aesthetic Identification: The Epaulette shark or Epaulette carpetshark has an elongated body, over half of which is comprised by the slender caudal peduncle. The five pairs of gill slits are small, with the fourth and fifth very close together. The Epaulette shark or Epaulette carpetshark has dorsal and anal fins that are set far back on an extremely long and thick tail. Its coloration provides protective camouflage, while its epaulette is speculated to be an eyespot for distracting or deterring predators. There are no spots on the snout. There are dark spots on the body and unpaired fins that are much smaller than the conspicuous large black epaulette spot, which is ringed with white, inconspicuous small dark spots behind and below. There are no white spots or reticular network. There are pale-marginal dark paired fins in the young sharks, that fade in adult sharks. Sometimes there are a few small dark spots on the adult paired fins. There are dark bands around the tail in the young sharks. The adults have a uniform light ventral tail surface. The pectoral and pelvic fins are broad and rounded and are thickly muscled.
Biology and Reproduction: The Epaulette shark is oviparous. Mating takes place from July to December, though in captivity reproduction occurs continuously. Courtship may be initiated by the female following and biting the male. The male then holds onto the pectoral fin of the female with his mouth and lies alongside her, while inserting one of his claspers into her cloaca. Copulation lasts about one and a half minutes. They typically deposit pairs of egg cases every 14 days from August to December. The eggs hatch in around 120 days. The growth rate of the young is slow at first but increases to about 5 cm or 2 inches per year after 3 months. Both males and females mature sexually at a length of 54–64 cm/ 1.8-2.1 feet, corresponding to an age of at least 7 years old.
Epaulette sharks are almost all parasitized by the praniza larval stage of gnathiid isopods. The larvae feed on blood and mostly attach to the skin around the cloaca and the claspers, though they are also found inside the mouth and on the gills. Other parasites of the Epaulette shark include a species of myxosporean in the genus Kudoa, which infests the skeletal muscles, the hemogregarine protozoan Haemogregarina hemiscyllii, which infects the blood, the ostracod Sheina orri, which attaches to the gills, and the nematode Proleptus australis, which infests the stomach. Most of these parasites are thought to cause little to no damage to the shark.
Behavioral Traits, Sensing and Intelligence: The Epaulette shark is much more active at dusk and at night. They often feed during low tide. They crawl about. They thrash their tail when the snout digs in the sand. 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 or predator awareness.
Epaulette sharks have a high tolerance of hypoxia, or being depleted of oxygen. They do this by increasing the blood supply to its brain and selectively shutting down non-essential neural functions. It is capable of surviving complete anoxia for an hour without ill effects, and at a much higher temperature than most other hypoxia-tolerant animals. In a tidal pool, the amount of dissolved oxygen in the pool can drop 80% or more overnight from the combined respiration of all the organisms within the pool. Research suggests that they are able to survive for over three hours in 5% of the atmospheric O2 level without losing behavioral responsiveness. In the laboratory, Epaulette sharks have survived for an hour without any oxygen at 30 °C (86 °F), which is also unusual in that most animals capable of tolerating oxygen deprivation do so at low temperatures. The physiological responses of the Epaulette shark to low oxygen are mediated by the nucleoside adenosine. In hypoxic conditions, the heart and ventilation rates drop sharply. The shark’s blood pressure falls by half as the blood vessels dilate to deliver more blood to the brain and heart. Unlike in bony fishes and tetrapods, the blood flow rate remains constant and there is no elevation of blood glucose levels. The brains of sharks only consume a third as much ATP as those of teleosts. The epaulette shark is able to lower this energy demand further by reducing the metabolism of certain areas of its brain, e.g. keeping the sensory nuclei functional while deactivating the motor nuclei. This allows the shark to supply enough ATP to prevent neuron death, while still remaining alert to its environment. (Mulveya, J.M.; Renshaw, G.M.C. (Aug 18, 2000). “Neuronal oxidative hypometabolism in the brainstem of the epaulette shark (Hemiscyllium ocellatum) in response to hypoxic pre-conditioning“. Neuroscience Letters. 290 (1): 1–4). and (Renshaw, G.M.C.; Kerrisk, C.B. & Nilsson, G.E. (2002). “The role of adenosine in the anoxic survival of the epaulette shark, Hemiscyllium ocellatum“. Comparative Biochemistry and Physiology B. 131 (2): 133–141.)
he senses of electroreception and olfaction are relied upon when searching for food.
Speed: Rather than swim, Epaulette sharks often crawl or walk by wriggling their bodies and pushing with their paired fins. The Epaulette 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. Its gait is similar to that of salamanders, an example of convergent evolution. This enables the shark to even crawl out of the water and across surface-exposed coral and rock.
Epaulette Shark Future and Conservation: They are of least concern. They are plentiful in the Great Barrier Reef. They may be threatened in New Guinea. Due to their hardiness and small size, Epaulette sharks are popular with both public and home aquaria.
Epaulette Shark Recorded Attacks on Humans: Not a threat to humans. They are unafraid of humans, and may nip if they are threatened or captured.