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Overview

Comprehensive Description

Biology

Oceanic species (Ref. 247). Epi- to bathypelagic at 1-3500 m (Ref. 58302). Makes diurnal vertical migrations from below 1,000 m in the day to or near the surface at night (Ref. 6871, 58302). Travels long vertical distances in excess of 2,000 to 3,000 m on a diel cycle (Ref. 247). Feeds free-living deepwater prey such as large squid, gonostomatids, crustaceans but is also a facultative ectoparasite on larger pelagic animals such as wahoo, tuna, billfishes, and cetaceans (Ref. 247). Ovoviviparous (Ref. 205), with 6-12 young per litter (Ref. 48844). The cookiecutter shark has specialized suctorial lips and a strongly modified pharynx that allow it to attach to the sides of it prey (Ref. 247). It then drives its saw-like lower dentition into the skin and flesh of its victim, twists about to cut out a conical plug of flesh, then pull free with the plug cradled by its scoop-like lower jaw and held by the hook-like upper teeth (Ref. 247). Teeth are shed as a complete unit; the lower teeth are swallowed, perhaps to maintain sufficient calcium levels in its body (Ref. 247). Interconnection at the bases of individual tooth allows a whole row of teeth to move if one tooth is touched. This shark is reported to radiate light for as long as three hours after its death. Not dangerous to people because of its small size and habitat preferences (Ref. 247).
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Distribution

Range Description

Widespread oceanic in temperate and tropical regions. In Australia, from isolated localities off Queensland, New South Wales, Tasmania, Western Australia, New Zealand and various localities throughout the South Pacific (including Fiji and the Cook Islands). Makes diurnal vertical migrations from below 1,000 m in the day to near the surface at night.
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Western Atlantic: Bahamas and southern Brazil. Eastern Atlantic: Cape Verde, Guinea to Sierra Leone, southern Angola and South Africa, including Ascension Island. Indo-Pacific: Mauritius to New Guinea, Lord Howe Island, and New Zealand (Ref. 26346), north to Japan and east to the Hawaiian Islands. Eastern Pacific: Easter Island (Ref. 9068) and the Galapagos.
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Geographic Range

Pelagic: The cookie-cutter shark is found in seas as far north as Japan and south to Southern Australia. It is a deep-water fish, and wide-ranging, often found near islands.

Biogeographic Regions: atlantic ocean (Native ); pacific ocean (Native )

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Circumglobal in warm seas (including Mascarenes, Hawaiian Islands).
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Physical Description

Morphology

Dorsal spines (total): 0; Dorsal soft rays (total): 0; Analspines: 0; Analsoft rays: 0; Vertebrae: 81 - 89
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Physical Description

The cookie-cutter shark is a typical member of the dogfish order; it has no anal fin, a thin, cigar shaped body, and short snout. It has suctorial lips, small upper teeth, and large, triangular cusped lower teeth in 25 to 32 rows. Coloration is medium grey to grey-brown, with a dark collar marking its throat. Females are larger than males, reaching perhaps 20 inches at full size. (Compagno 1984)

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Size

Maximum size: 390 mm TL
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Max. size

42.0 cm TL (male/unsexed; (Ref. 48844)); 56 cm TL (female)
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Diagnostic Description

Description

Feeds on large squids, gonostomatids, crustaceans, and may also bite circular plugs of tissue from large pelagic animals (wahoo, tuna, billfishes, cetaceans etc.) (Ref. 6577).Travels long vertical distances in excess of 2000 to 3000 m on a diel cycle. Presumably ovoviviparous. Tooth replacement: teeth are shed as a complete unit. Interconnection at the bases of individual tooth allows a whole row of teeth to move if one tooth is touched. This shark is reported to radiate light for as long as three hours after its death.
  • Anon. (1996). FishBase 96 [CD-ROM]. ICLARM: Los Baños, Philippines. 1 cd-rom pp.
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The cookiecutter shark Isistius brasiliensis is distinctive for the prominent dark collar marking around its throat, large nearly symmetrical caudal fin with a long ventral lobe over 2/3 length of dorsal caudal margin, and moderately large lower teeth in 25-32 rows. Eyes set anterior of head but sufficiently far back to lack an extensive anterior binocular field. Pectoral fins subquadrate; pelvic fins larger than dorsal fins (Ref.247). Tooth count: 30-37/25-31. Vertebral count: 81-89. Spiral valve count: 8-10 (Ref. 48844). Dark brown dorsally, paler ventrally except for blackish band across throat; tips of caudal lobe blackish (Ref. 6577). As with the other member of the genus Isistius , it has a characteristic small cigar-shaped body with two small close-set spineless dorsal fins far posterior on back, no anal fin, huge, triangular-cusped teeth without blades, short, bulbous snout and a unique suctorial lips (Ref. 247).
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Ecology

Habitat

Known from seamounts and knolls
  • Stocks, K. 2009. Seamounts Online: an online information system for seamount biology. Version 2009-1. World Wide Web electronic publication.
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Habitat and Ecology

Habitat and Ecology
Oceanic waters. This species makes diurnal vertical migrations from below 1,000 m in the day, to near the surface at night. The cookie-cutter’s trademark bites are relatively common on large pelagic fish and cetaceans. Little is known of its biology.

Systems
  • Marine
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Environment

bathypelagic; oceanodromous (Ref. 51243); marine; depth range 0 - 3700 m (Ref. 55584), usually 0 - 1000 m (Ref. 89423)
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Cookie-cutter sharks are wide-ranging creatures, found in tropical oceanic climates all across the world. They tend to be found closer to islands, but they have been caught in open sea, as well.

Aquatic Biomes: benthic ; reef ; coastal

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Depth range based on 53 specimens in 1 taxon.
Water temperature and chemistry ranges based on 43 samples.

Environmental ranges
  Depth range (m): 20 - 3500
  Temperature range (°C): 1.485 - 27.169
  Nitrate (umol/L): 0.835 - 40.241
  Salinity (PPS): 34.411 - 35.913
  Oxygen (ml/l): 1.240 - 5.741
  Phosphate (umol/l): 0.348 - 2.883
  Silicate (umol/l): 2.141 - 151.223

Graphical representation

Depth range (m): 20 - 3500

Temperature range (°C): 1.485 - 27.169

Nitrate (umol/L): 0.835 - 40.241

Salinity (PPS): 34.411 - 35.913

Oxygen (ml/l): 1.240 - 5.741

Phosphate (umol/l): 0.348 - 2.883

Silicate (umol/l): 2.141 - 151.223
 
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Depth: 0 - 3500m.
Recorded at 3500 meters.

Habitat: bathypelagic.
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Migration

Oceanodromous. Migrating within oceans typically between spawning and different feeding areas, as tunas do. Migrations should be cyclical and predictable and cover more than 100 km.
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Trophic Strategy

Food Habits

Like many sharks, the cookie-cutter shark is a carnivore. It attaches itself to its prey with its strong sucking mouth, and then twists about, using its sharp lower teeth to slice out a plug of flesh, which can sometimes be twice as deep as its diameter. It then uses its hook-like upper teeth to hold the plug, while the lower teeth scoop the plug out. Detaching, it swims away to enjoy its meal. It preys on deep water organisms, including crustaceans, squid, large bony fishes, cetaceans, and even large sharks. It is bioluminescent, able to emit a greenish light from its belly. It may use this light to attract the attention of potential victims (Compagno 1984, Roesch 1997).

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Life History and Behavior

Life Cycle

Presumably ovoviviparous; 6 or 7 large eggs have been found in ovaries (Ref. 247). Distinct pairing with embrace (Ref. 205). Viviparous, without a yolk sac placenta, 6-12 young per litter. Males mature at about 36 cm, with a maximum length of 42 cm; females mature at 39 cm, with a maximum length of 56 cm. Size at birth is unknown. (Ref. 48844).
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Reproduction

Reproduction of the cookie-cutter shark is accomplished through internal fertilization. The male has instead two 'claspers' (pterygopodes), located on his underside in the rear. Fertilization is accomplished by his insertion of one of his claspers into the female's cloaca. Like other small sharks, this shark is oviparous, and the female coats her eggs in a horny casing before attaching them to rocks and seaweed. Hatching can take place after 12 to 22 months. When the young emerge, they are fully developed and capable of hunting for themselves. Males mature at approximately 14 inches and grow to a size of 16 inches, while females mature at 16 inches and reach up to 20 inches (Stoakely 1997).

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Molecular Biology and Genetics

Molecular Biology

Statistics of barcoding coverage: Isistius brasiliensis

Barcode of Life Data Systems (BOLDS) Stats
Public Records: 0
Specimens with Barcodes: 5
Species With Barcodes: 1
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Conservation

Conservation Status

IUCN Red List Assessment


Red List Category
LC
Least Concern

Red List Criteria

Version
3.1

Year Assessed
2003

Assessor/s
Stevens, J. (SSG Australia & Oceania Regional Workshop, March 2003)

Reviewer/s
Cavanagh, R.D. & Francis, M.P. (Shark Red List Authority)

Contributor/s

Justification
Isistius brasiliensis is widespread but with patchy distribution records. It is too small (up to about 50 cm total length (TL)) to be regularly taken by fisheries and although it is occasionally caught by pelagic longlines, and sometimes in midwater trawls and plankton nets there are no significant threats to this species.
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IUCN Red List of Threatened Species: least concern

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Population

Population
Nothing is known about population size.

Population Trend
Unknown
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Threats

Major Threats
Because of its small size it is only occasionally taken by fisheries.
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Least Concern (LC)
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Management

Conservation Actions

Conservation Actions
There are currently no conservation measures in place for this species.
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Relevance to Humans and Ecosystems

Benefits

Importance

fisheries: minor commercial; price category: unknown; price reliability:
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Economic Importance for Humans: Negative

They have a potential negative impact on fisheries, as they prey on commercially important fish, but damage is slight. The attacks on submarines are considered at most a nuisance. Because of its small size, and deep water habitat, this species is of little or no danger to swimmers and divers.

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Wikipedia

Cookiecutter shark

For other species of cookiecutter sharks, see Isistius.

The cookiecutter shark (Isistius brasiliensis), also called the cigar shark, is a species of small dogfish shark in the family Dalatiidae. This shark occurs in warm, oceanic waters worldwide, particularly near islands, and has been recorded from as deep as 3.7 km (2.3 mi). It migrates vertically up to 3 km (1.9 mi) every day, approaching the surface at dusk and descending with the dawn. Reaching only 42–56 cm (17–22 in) in length, the cookiecutter shark has a long, cylindrical body with a short, blunt snout, large eyes, two tiny spineless dorsal fins, and a large caudal fin. It is dark brown in color, with light-emitting photophores covering its underside except for a dark "collar" around its throat and gill slits.

The name "cookiecutter shark" refers to its feeding habit of gouging round plugs, as if cut out with a cookie cutter, out of larger animals. Marks made by cookiecutter sharks have been found on a wide variety of marine mammals and fishes, as well as on submarines, undersea cables, and even human bodies. It also consumes whole smaller prey such as squid. Cookiecutter sharks have adaptations for hovering in the water column and likely rely on stealth and subterfuge to capture more active prey. Its dark collar seems to mimic the silhouette of a small fish, while the rest of its body blends into the downwelling light via its ventral photophores. When a would-be predator approaches the lure, the shark attaches itself using its suctorial lips and specialized pharynx and neatly excises a chunk of flesh using its bandsaw-like set of lower teeth. This species has been known to travel in schools.

Though rarely encountered because of its oceanic habitat, a handful of documented attacks on humans were apparently caused by cookiecutter sharks. Nevertheless, this diminutive shark is not regarded as highly dangerous. The International Union for Conservation of Nature (IUCN) has listed the cookiecutter shark under Least Concern, as it is widely distributed, has no commercial value, and is not particularly susceptible to fisheries.

Taxonomy[edit]

French naturalists Jean René Constant Quoy and Joseph Paul Gaimard originally described the cookiecutter shark during the 1817–1820 exploratory voyage of the corvette Uranie under Louis de Freycinet, giving it the name Scymnus brasiliensis because the type specimen was caught off Brazil. In 1824, their account was published as part of Voyage autour du monde...sur les corvettes de S.M. l'Uranie et la Physicienne, Louis de Freycinet's 13-volume report on the voyage.[2][3] In 1865, American ichthyologist Theodore Nicholas Gill coined the new genus Isistius for this species, after Isis, the Egyptian goddess of light.[4][5]

One of the earliest accounts of the wounds left by the cookiecutter shark on various animals is in ancient Samoan legend, which held that atu (skipjack tuna) entering Palauli Bay would leave behind pieces of their flesh as a sacrifice to Tautunu, the community chief. In later centuries, various other explanations for the wounds were advanced, including lampreys, bacteria, and invertebrate parasites.[6][7] In 1971, Everet Jones of the U.S. Bureau of Commercial Fisheries (a predecessor of the National Marine Fisheries Service) discovered the cigar shark, as it was then generally known, was responsible. Shark expert Stewart Springer thus popularized the name "cookiecutter shark" for this species (though he originally called them "demon whale-biters").[8] Other common names used for this shark include luminous shark, smalltooth cookiecutter shark, and smooth cookiecutter shark.[9]

Description[edit]

side view of the head of a preserved shark
The cookiecutter shark has a short, rounded head with large, anteriorly placed eyes and a transverse mouth.

The cookiecutter shark has an elongated, cigar-shaped body with a short, bulbously rounded snout. The nostrils have a very short flap of skin in front. The large, oval, green eyes are placed forward on the head, though not so that there is extensive binocular vision. Behind the eyes are large spiracles, positioned on the upper surface of the head. The mouth is short, forming a nearly transverse line, and is surrounded by enlarged, fleshy, suctorial lips. There are 30–37 tooth rows in the upper jaw and 25–31 tooth rows in the lower jaw, increasing with body size. The upper and lower teeth are extremely different: the upper teeth are small, narrow, and upright, tapering to a single, smooth-edged cusp. The lower teeth are also smooth-edged, but much larger, broader, and knife-like, with their bases interlocking to form a single saw-like cutting edge. The five pairs of gill slits are small.[3][5][6]

The pectoral fins are short and roughly trapezoidal in shape. Two spineless dorsal fins are placed far back on the body, the first originating just ahead of the pelvic fins and the second located just behind. The second dorsal fin is slightly larger than the first, and the pelvic fins are larger than either. The anal fin is absent. The caudal fin is broad, with the lower lobe almost as large as the upper, which has a prominent ventral notch.[3][6] The dermal denticles are squarish and flattened, with a slight central concavity and raised corners. The cookiecutter shark is chocolate brown in color, becoming subtly lighter below, and there is a dark "collar" that wraps around the gill region. The fins have translucent margins, except for the caudal fin, which has a darker margin.[5] Complex, light-producing organs called photophores densely cover the entire underside, except for the collar, and produce a vivid green glow.[5] The maximum recorded length for this species is 42 cm (17 in) for males and 56 cm (22 in) for females.[9]

Distribution and habitat[edit]

Inhabiting all of the world's major tropical and warm-temperate oceanic basins, the cookiecutter shark is most common between the latitudes of 20°N and 20°S, where the surface water temperature is 18–26 °C (64–79 °F).[3] In the Atlantic, it has been reported from off the Bahamas and southern Brazil in the west, Cape Verde, Guinea to Sierra Leone, southern Angola, and South Africa in the east, and Ascension Island in the south. In the Indo-Pacific region, it has been caught from Mauritius to New Guinea, Australia, and New Zealand, including Tasmania and Lord Howe Island, as well as off Japan. In the central and eastern Pacific, it occurs from Fiji north to the Hawaiian Islands, and east to the Galápagos, Easter, and Guadalupe Islands. Fresh wounds observed on marine mammals suggest this shark may range as far as California in warm years.[3][5][6]

Based on catch records, the cookiecutter shark appears to conduct a diel vertical migration of up to 3 km (1.9 mi) each way.[6] It spends the day at a depth of 1–3.7 km (0.62–2.30 mi), and at night it rises into the upper water column, usually remaining below 85 m (279 ft), but on rare occasions venturing to the surface.[1][5] This species may be more tolerant of low dissolved oxygen levels than sharks in the related genera Euprotomicrus and Squaliolus.[6] It is frequently found near islands, perhaps for reproductive purposes or because they hold congregations of large prey animals.[6] In the northeastern Atlantic, most adults are found between 11°N and 16°N, with the smallest and largest individuals being found in lower and higher latitudes, respectively.[10] There is no evidence of sexual segregation.[11]

Biology and ecology[edit]

The suctorial lips and large lower teeth of the cookiecutter sharks are adaptations for its parasitic lifestyle.

Best known for biting neat round chunks of tissue from marine mammals and large fish, the cookiecutter shark is considered a facultative ectoparasite, as it also wholly ingests smaller prey. It has a wide gape and a very strong bite, by virtue of heavily calcified cranial and labial cartilages.[12] With small fins and weak muscles, this ambush predator spends much of its time hovering in the water column.[6][13] To maintain neutral buoyancy, its liver, which can comprise some 35% of its weight, is rich in low-density lipids. As this species has higher skeletal density than Euprotomicrus or Squaliolus, its body cavity and liver are proportionately much larger, and the oil content is much higher.[6][14] Its large caudal fin allows for a quick burst of speed to catch larger, faster prey that come in range.[14]

The cookiecutter shark regularly replaces its teeth like other sharks, but sheds its lower teeth in entire rows rather than one at a time. A cookiecutter shark 14 cm (5.5 in) long has been calculated to have shed 15 sets of lower teeth by the time it is 50 cm (20 in) long, totaling 435–465 teeth.[11] This represents a significant investment of resources and is probably why the shark swallows its old sets of teeth, so that it can recycle the calcium content.[6] Unlike other sharks, the retina of the cookiecutter shark has ganglion cells concentrated in a concentric area rather than in a horizontal streak across the visual field; this may help to focus on prey in front of the shark.[15] This shark has been known to travel in schools, which may increase the effectiveness of its lure (see below), as well as discourage counterattacks by much larger predators.[12]

Bioluminescence[edit]

a small shark lying belly-up, with a clear dark brown band around the throat
The dark collar of the cookiecutter shark is believed to act as a lure.

The intrinsic green luminescence of the cookiecutter shark is the strongest known of any shark, and has been reported to persist for three hours after it has been taken out of water.[8][14][16][17] The ventrally positioned photophores serve to disrupt its silhouette from below by matching the downwelling light, a strategy known as counter-illumination, that is common among bioluminescent organisms of the mesopelagic zone. The individual photophores are set around the denticles and are small enough that they cannot be discerned by the naked eye, suggesting they have evolved to fool animals with high visual acuity and/or at close distances.[12]

Set apart from the glowing underside, the darker, nonluminescent collar tapers at both sides of the throat, and has been hypothesized to serve as a lure by mimicking the silhouette of a small fish from below. The appeal of the lure would be multiplied in a school of sharks. If the collar does function in this way, the cookiecutter shark would be the only known case of bioluminescence in which the absence of light attracts prey, while its photophores serve to prevent premature detection by incoming would-be predators.[12][13] As the shark can only match a limited range of light intensities, its vertical movements likely serve to preserve the effectiveness of its disguise across various times of day and weather conditions.[12]

Feeding[edit]

a silvery fish with round concavities gouged from its side
Pomfrets are one of the many species parasitized by the cookiecutter shark.

Virtually every type of medium to large-sized oceanic animal sharing the habitat of the cookiecutter shark is open to attack: bite scars have been found on cetaceans (including porpoises, dolphins, beaked whales, sperm whales, and baleen whales), pinnipeds (including fur seals, leopard seals, and elephant seals), dugongs, sharks (including blue sharks, goblin sharks, basking sharks, great white sharks, megamouth sharks and smalltooth sand tiger sharks), stingrays (including deepwater stingrays, pelagic stingrays and sixgill stingrays), and bony fishes (including billfishes, tunas, dolphinfishes, jacks, escolars, opahs, and pomfrets).[3][14][18][19] The cookiecutter shark also regularly hunts and eats entire squid with a mantle length of 15–30 cm (5.9–11.8 in), comparable in size to the shark itself, as well as bristlemouths, copepods, and other prey of more modest dimensions.[11]

The flank of a stranded whale, showing several round scars
Round scars from cookiecutter shark bites are found on many cetaceans, such as this beached Gray's beaked whale.

Parasitic attacks by the cookiecutter shark leave a round "crater wound", averaging 5 cm (2.0 in) across and 7 cm (2.8 in) deep.[20] The prevalence of these attacks can be high; off Hawaii, nearly every adult spinner dolphin bears scars from this species.[21] Diseased or otherwise weakened animals appear to be more susceptible; in the western Atlantic, there are records of emaciated beached melon-headed whales with dozens to hundreds of recent and healing cookiecutter shark wounds, while such wounds are rare on nonemaciated beached whales.[22] The impact of parasitism on prey species, in terms of resources diverted from growth or reproduction, is uncertain.[21]

The cookiecutter shark exhibits a number of specializations to its mouth and pharynx for its parasitic lifestyle. The shark first secures itself to the body surface of its prey by closing its spiracles and retracting its basihyal (tongue) to create negative pressure; its suctorial lips ensure a tight seal.[12][14] It then bites, using its narrow upper teeth as anchors while its lower teeth slices into the prey. Finally, the shark twists and rotates its body to complete a circular cut, quite possibly aided by the initial forward momentum and subsequent struggles of its prey.[12] The action of the lower teeth may also be assisted by back-and-forth vibrations of the jaw, a mechanism akin to that of an electric carving knife.[20] This shark's ability to create strong suction into its mouth is likely also of utility in capturing smaller prey such as squid.[12] Has been known to eat off human weiners and vaginas

Life history[edit]

Like other dogfish sharks, the cookiecutter shark is aplacental viviparous, with the developing embryos being sustained by yolk until birth. Females have two functional uteruses and give birth to litters of 6 to 12 pups.[3][23] There is a record of a female carrying 9 embryos 12.4–13.7 cm (4.9–5.4 in) long; though they were close to the birth size, they still had well-developed yolk sacs, suggesting a slow rate of yolk absorption and a long gestation period. The embryos had developed brown pigmentation, but not the dark collar or differentiated dentition. Newborn cookiecutter sharks measure 14–15 cm (5.5–5.9 in) long.[23] Males attain sexual maturity at a length of 36 cm (14 in), and females at a length of 39 cm (15 in).[3]

Human interactions[edit]

dorsal view of the front part of a small shark
A cookiecutter shark is caught on a longline near Hawaii; note the large spiracles located behind the eyes.

Favoring offshore waters and thus seldom encountered by humans, the cookiecutter shark is not considered very dangerous because of its small size. However, it has been implicated in a few attacks; in one notable case, a school of fierce, 30 cm (12 in) long fish with blunt snouts attacked an underwater photographer on an open ocean dive. Similar reports have come from shipwreck survivors, of suffering small, clean, deep bites during nighttime.[3][14] In March 2009, Maui resident Mike Spalding was bitten by a cookiecutter shark while swimming across Alenuihaha Channel.[24][25] There are at least two records of bodies recovered from the water with post-mortem cookiecutter shark bites.[14][26]

During the 1970s, several U.S. Navy submarines were forced back to base for repairs by cookiecutter shark bites to the neoprene boots of their AN/BQR-19 sonar domes, which caused the sound-transmitting oil inside to leak and impaired navigation. An unknown enemy weapon was initially feared, before this shark was identified as the culprit, and the problem was solved by installing fiberglass covers around the domes.[18][27] In the 1980s, some thirty U.S. Navy submarines were damaged by cookiecutter shark bites, mostly to the rubber-sheathed electric cable leading to the sounding probe used to ensure safety when surfacing in shipping zones. Again, the solution was to apply a fiberglass coating.[28] Oceanographic equipment and telecommunications cables have also been damaged by this species.[3][18]

The harm inflicted by cookiecutter sharks on fishing nets and economically important species may have a minor negative effect on commercial fisheries.[6][28] The shark itself is too small to be of value, and is only infrequently taken, as bycatch, on pelagic longlines and in midwater trawls and plankton nets. The lack of significant population threats, coupled with a worldwide distribution, has led the IUCN to assess the cookiecutter shark as of Least Concern.[1]

References[edit]

  1. ^ a b c Stevens, J. (SSG Australia & Oceania Regional Workshop, March 2003) (2003). Isistius brasiliensis. In: IUCN 2008. IUCN Red List of Threatened Species. Retrieved January 26, 2010.
  2. ^ Quoy, J.R.C. and J.P. Gaimard (1824–1825). "des Poissons. Chapter IX". In de Freycinet, L. Voyage autour du Monde...exécuté sur les corvettes de L. M. "L'Uranie" et "La Physicienne," pendant les années 1817, 1818, 1819 et 1820. Paris. pp. 192–401. 
  3. ^ a b c d e f g h i j Ebert, D.A. (2003). Sharks, Rays, and Chimaeras of California. University of California Press. pp. 73–75. ISBN 0-520-23484-7. 
  4. ^ Gill, T.N. (1865). "Synopsis of the eastern American sharks". Proceedings of the Academy of Natural Sciences of Philadelphia 16 (5): 258–265. 
  5. ^ a b c d e f Bester, C. Biological Profiles: Cookiecutter Shark. Florida Museum of Natural History Ichthyology Department. Retrieved on January 26, 2010.
  6. ^ a b c d e f g h i j k Compagno, L.J.V. (1984). Sharks of the World: An Annotated and Illustrated Catalogue of Shark Species Known to Date. Rome: Food and Agricultural Organization. p. 93–95. ISBN 92-5-101384-5. 
  7. ^ Jones, E.C. (1971). "Isistius brasiliensis, a Squaloid Shark, the Probable Cause of Crater Wounds on Fishes and Cetaceans". Fisheries Bulletin 69 (4): 791–798. 
  8. ^ a b Bright, M. (2000). The Private Life of Sharks: The Truth Behind the Myth. Stackpole Books. p. 215. ISBN 0-8117-2875-7. 
  9. ^ a b Froese, Rainer and Pauly, Daniel, eds. (2009). "Isistius brasiliensis" in FishBase. November 2009 version.
  10. ^ Muñoz-Chápuli, R., J.C. Rey Salgado and J. M. De La Serna (1988). "Biogeography of Isistius brasiliensis in the north-eastern Atlantic, inferred from crater wounds on swordfish (Xiphias gladius)". Journal of the Marine Biological Association of the United Kingdom 68 (2): 315–321. doi:10.1017/S0025315400052218. 
  11. ^ a b c Strasburg, D.W. (March 30, 1963). "The Diet and Dentition of Isistius brasiliensis, with Remarks on Tooth Replacement in Other Sharks". Copeia 1963 (1): 33–40. doi:10.2307/1441272. JSTOR 1441272. 
  12. ^ a b c d e f g h Widder, E.A. (November 1998). "A predatory use of counterillumination by the squaloid shark, Isistius brasiliensis". Environmental Biology of Fishes 53 (3): 267–273. doi:10.1023/A:1007498915860. 
  13. ^ a b Milius, S. (August 1, 1998). "Glow-in-the-dark shark has killer smudge". Science News. Retrieved on January 26, 2010.
  14. ^ a b c d e f g Martin, R.A. Deep Sea: Cookiecutter Shark. ReefQuest Centre for Shark Research. Retrieved on January 26, 2010.
  15. ^ Bozzano, A. and S.P. Collin (April 2000). "Retinal ganglion cell topography in elasmobranchs". Brain Behavior and Evolution 55 (4): 191–208. doi:10.1159/000006652. 
  16. ^ Hoar, W.S., D.J. Randall, and F.P. Conte (1969). Fish Physiology: Reproduction and Growth, Bioluminescence, Pigments, and Poisons. Academic Press. p. 385. ISBN 0-12-350403-1. 
  17. ^ Glenday, C., ed. (2013). Guinness World Records. Random House LLC. p. 63. ISBN 034554711X. 
  18. ^ a b c Martin, R.A. Squaliformes: Dogfish Sharks. ReefQuest Centre for Shark Research. Retrieved on January 26, 2010.
  19. ^ Hoyos-Padilla, M., Y.P. Papastamatiou, J. O'Sullivan and C.G. Lowe (2013). "Observation of an Attack by a Cookiecutter Shark (Isistius brasiliensis) on a White Shark (Carcharodon carcharias)". Pacific Science 67 (1): 129–134. 
  20. ^ a b Martin, R.A. Attacked by a Dogfish. ReefQuest Centre for Shark Research. Retrieved on January 26, 2010.
  21. ^ a b Heithaus, M.R. (2004). "Predator-Prey Interactions". In Carrier, J.C., J.A. Musick and M.R. Heithaus. Biology of Sharks and Their Relatives. CRC Press. pp. 487–521. ISBN 0-8493-1514-X. 
  22. ^ Gasparini, J.L. and I. Sazima (1996). "A stranded melon-headed whale, Peponocephala electra, in southeastern Brazil, with comments on wounds from the cookiecutter shark, Isistius brasiliensis". Marine Mammal Science 12 (2): 308–312. doi:10.1111/j.1748-7692.1996.tb00582.x. 
  23. ^ a b Gadig, O.B.F. and U.L. Gomes (May 2002). "First report on embryos of Isistius brasiliensis". Journal of Fish Biology 60 (5): 1322–1325. doi:10.1111/j.1095-8649.2002.tb01723.x. 
  24. ^ Perry, B. (March 21, 2009). "Cookie-cutter sharks 'sort of a mosquito of the sea'". The Maui News. Retrieved on January 26, 2010.
  25. ^ Honebrink, R., R. Buch, P. Galpin and G.H. Burgess (2011). "First documented attack on a live human by a cookiecutter shark (Squaliformes, Dalatiidae: Isistius sp.)". Pacific Science (In press). doi:10.2984/65.3.365. 
  26. ^ Makino, Y., K. Tachihara, S. Ageda, T. Arao, C. Fuke and T. Miyazaki (June 2004). "Peculiar Circular and C-Shaped Injuries on a Body from the Sea". The American Journal of Forensic Medicine and Pathology 25 (2): 169–171. doi:10.1097/01.paf.0000127390.07879.62. 
  27. ^ Johnson, C.S. (1978). "Sea Creatures and the Problem of Equipment Damage". U.S. Naval Institute Proceedings. August 1978: 106–107. 
  28. ^ a b Maniguet, X. (2007). The Jaws of Death: Sharks as Predator, Man as Prey. Skyhorse Publishing. pp. 102–103. ISBN 1-60239-021-5. 

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