C
Species Profile

Cookiecutter Shark

Isistius brasiliensis

The deep-sea donut-cutter
NOAA Observer Project / public domain

Cookiecutter Shark Ocean Range

Marine Species

Cookiecutter Shark (Isistius brasiliensis) is a warm-temperate to tropical pelagic/mesopelagic shark with a circumglobal range in the Atlantic, Pacific and Indian Oceans. Mostly absent from polar waters, it occurs roughly between 40°N and 35–40°S. Depths range from the surface to about 3,700 m; it stays deep by day and moves up into the upper few hundred meters at night.

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Ocean Regions 12

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Cookiecutter shark (Isistius brasiliensis)

At a Glance

Ocean Species
Also Known As cigar shark
Diet Sanguivore
Activity Nocturnal
Lifespan 12 years
Weight 1 lbs
Status Least Concern
Did You Know?

Adults are typically ~40-50 cm long; maximum reported total length is ~56 cm (female) (FAO/Compagno; Ebert et al.).

Scientific Classification

A small, deep-sea dogfish shark famous for excising neat, circular plugs of flesh from larger animals (and occasionally inanimate objects) using a suction-assisted bite. It is widely distributed in warm-temperate and tropical oceans and performs diel vertical migrations (deeper by day, nearer the surface at night).

Kingdom
Animalia
Phylum
Chordata
Class
Chondrichthyes
Order
Squaliformes
Family
Dalatiidae
Genus
Isistius
Species
Isistius brasiliensis

Distinguishing Features

  • Small shark with a cylindrical body and large eyes (deep-sea adapted).
  • Dark brown body with a distinctive lighter collar/band behind the head in many individuals.
  • Specialized lower jaw teeth form a cutting blade; leaves crater-like circular wounds on prey.
  • Bioluminescence on the underside (counterillumination), with a less luminous collar region used in camouflage/luring hypotheses.

Physical Measurements

Males and females differ in size

Length
♂ 1 ft 3 in (6 in – 1 ft 5 in)
♀ 1 ft 6 in (1 ft 3 in – 1 ft 10 in)
Weight
♂ 1 lbs (0 lbs – 2 lbs)

Appearance

Primary Colors
Brown Gray
Secondary Colors
Black Cream
Skin Type Tough, deep-sea shark skin covered in placoid scales (dermal denticles), typical of Dalatiidae (kitefin sharks). Ventral surface bears numerous photophores (bioluminescent organs) enabling counterillumination; the dark collar is comparatively non-luminous.
Distinctive Features
  • Small dalatiid shark with a compact, cylindrical ('cigar-shaped') body and short, blunt snout; large eyes adapted to low light (mesopelagic) (e.g., Compagno 2001; Ebert et al. 2013).
  • Cookiecutter Shark (Isistius brasiliensis) has thick lips and suction that let it seal on prey and cut out neat round plugs of flesh, leaving round 'cookie-cutter' wounds on animals and objects.
  • Extreme tooth heterodonty: small upper teeth and very large, triangular, interlocking, serrated lower teeth form a cutting blade for gouging; lower tooth rows are periodically replaced as a unit (reported for Isistius) (Compagno 2001).
  • The Cookiecutter shark (Isistius brasiliensis) has a glowing belly for counterillumination, and a darker collar band that may act like a false-prey signal while the body glows.
  • Cookiecutter Shark (Isistius brasiliensis) makes daily up-and-down moves: usually deeper in daytime and near the surface at night; seen from the surface down to about 3,700 m.
  • Adult size is small: commonly ~30-50 cm total length; reported maximum total length about 56 cm (females larger than males) (Compagno 2001; Ebert et al. 2013).
  • Reproduction is aplacental viviparity (ovoviviparity). Pups are born very small, about 14–15 cm long, and litters range from single digits to the low teens.
  • Overall appearance and behavior are unlike large macropredatory sharks (e.g., great white); it is a small, deep-sea ectoparasitic/carnivorous dalatiid where human incidents are rare and typically non-fatal (general incident summaries in shark references).

Sexual Dimorphism

Sexual dimorphism is primarily size- and sex-organ based: females attain larger maximum total length than males; males bear claspers. Reported maximum size is ~56 cm TL for females versus smaller maxima for males (often cited ~42 cm TL) (Compagno 2001; Ebert et al. 2013).

♂
  • Smaller adult total length than females (commonly cited male maximum ~42 cm TL in major shark catalogs).
  • Presence of claspers (paired intromittent organs) on the pelvic fins.
♀
  • Larger maximum adult total length (commonly cited maximum ~56 cm TL).
  • Generally more robust body at comparable maturity due to larger ultimate size.

Did You Know?

Adults are typically ~40-50 cm long; maximum reported total length is ~56 cm (female) (FAO/Compagno; Ebert et al.).

It leaves distinctive crater-like, round wounds about 1-7 cm (0.4-2.8 in) in diameter on whales, dolphins, large fishes, and even other sharks.

Its lower jaw has a single, saw-like row of oversized triangular teeth; the upper jaw has much smaller grasping teeth-built for anchoring + excising tissue (FAO/Compagno).

Cookiecutter sharks can bite inanimate objects; circular pits have been documented on submarine sonar domes and undersea cables, helping popularize the common name in naval circles.

It performs diel vertical migration: commonly deeper in the mesopelagic by day and nearer the surface at night, matching the daily movements of many prey (FAO/Compagno; Ebert et al.).

The belly is covered in light-producing photophores for counterillumination, while a darker "collar" near the head may act as a deceptive lure-like contrast in dim water (bioluminescence literature; Widder and others).

It is ovoviviparous (aplacental viviparity); reported litter sizes are commonly ~6-12 pups (FAO/Compagno).

Unique Adaptations

  • Counterillumination via ventral photophores: producing light to match downwelling moon/starlight reduces the shark's silhouette when viewed from below-an advantage for a small predator approaching larger animals from beneath.
  • Dark "collar" and luminous body contrast: the abrupt dark band behind the head against a glowing belly is hypothesized to function in deception/luring in low light, a distinctive pattern among many dalatiids.
  • Extreme heterodont dentition: tiny upper teeth help grip; huge lower teeth form a cutting ring-specialized for removing plugs of tissue rather than slicing strips.
  • Whole-tooth-row replacement: the enlarged lower teeth are replaced in a synchronized set; shed teeth may be swallowed, potentially conserving minerals in the nutrient-poor deep sea (reported for Isistius in standard references).
  • Large, oil-rich liver for buoyancy: like many deep-sea sharks, buoyancy is aided by a high-lipid liver, reducing the energy cost of hovering and vertical travel.
  • Compact, muscular suction bite mechanics: thick lips and a robust buccal (oral) seal allow the shark to attach securely to fast-moving, much larger hosts during the excision bite.

Interesting Behaviors

  • Diel vertical migration: spends daylight hours at greater depth (mesopelagic/bathypelagic) and rises toward the upper water column at night to encounter migrating prey.
  • Suction-assisted feeding: seals its thick lips to the target, then uses powerful jaw muscles and body rotation to excise a near-circular plug of flesh.
  • Ectoparasitic predation: rather than subduing large prey, it "samples" larger animals (cetaceans, pinnipeds, billfish, tunas, and sharks), taking small but energy-rich bites repeatedly over time.
  • Scavenging/opportunism: will feed on carrion and may attack injured animals; bite marks on dead whales and large fishes are common in warm waters.
  • Light-associated encounters: more frequently observed near the surface at night and sometimes drawn to ship lights, which can increase bycatch risk.
  • Dalatiidae context (kitefin sharks): shares with relatives a deep-water lifestyle, relatively slow cruising, and a strategy of taking high-calorie prey (flesh chunks, large fishes, squid) rather than constant filter-feeding or fast pursuit.

Cultural Significance

The cookiecutter shark (Isistius brasiliensis) is a deep-sea icon: its round "cookie-cutter" bites on whales, dolphins, tunas, and billfish are famous. Mid-20th-century gouges on submarines led to public interest and sea stories, especially in the tropical Pacific.

Myths & Legends

During the Cold War, sailors in tropical Pacific waters (like Hawaii) told of perfect round holes in rubber sonar domes. These tales were later blamed on the cookiecutter shark (Isistius brasiliensis) and became sea lore.

Fishermen call a sneaky night animal the "plug-biter." In tropical ports they tell of a Cookiecutter Shark (Isistius brasiliensis) that leaves round bites on tunas and billfish, stealing perfect mouthfuls.

People often say the cookiecutter shark cuts out flesh like a pastry cutter. That strong image gave it its name and keeps appearing in documentaries and sea stories.

Conservation Status

LC Least Concern

Widespread and abundant in the wild.

Population Unknown

Life Cycle

Birth 9 pups
Lifespan 12 years

Lifespan

In the Wild
8–16 years
In Captivity
1–6 years

Reproduction

Mating System Data Deficient
Social Structure Solitary
Breeding Pattern Transient
Fertilization Internal Fertilization
Birth Type Internal_fertilization

Behavior & Ecology

Social None (solitary) Group: 1
Activity Nocturnal
Diet Sanguivore Circular plugs of skin and muscle excised from large pelagic fishes (commonly tunas and billfishes).
Seasonal Migratory 2 mi

Temperament

Cryptic, non-territorial, and typically non-aggressive toward humans; interactions with large animals are usually via brief, stealthy excision feeding rather than pursuit or prolonged attack.
Cookiecutter sharks are ectoparasitic predators that use suction and a rotating bite to remove round plugs of flesh from large fish and marine mammals; they also eat squid and small fish.
Cookiecutter shark (Isistius brasiliensis) has strong day and night up-and-down movement: usually deeper by day and shallower at night, feeding near the surface; found from the surface down to about 3,700 m.
Sexually dimorphic in size: females are larger than males, with reported maximum total length about 56 cm for females and about 42 cm for males.
Longevity: no validated, species-specific maximum lifespan estimate is established in the primary literature due to limited age-and-growth data for this deep-sea species; therefore an exact lifespan cannot be cited reliably.

Communication

None documented; sharks (including dalatiids) are not known to produce deliberate vocal signals for social communication.
Chemoreception (olfaction/gustation) likely used to locate hosts, carrion, and prey; tracking of odor plumes is a primary long-range sensory mode in sharks.
Mechanoreception via the lateral line to detect water movements from nearby prey/hosts in low-light pelagic conditions.
Electroreception (ampullae of Lorenzini) to detect bioelectric fields at close range during the final approach/attachment phase.
Tactile cues during suction attachment and biting; direct physical contact is central to feeding interactions rather than social signaling.
Vision adapted to low light; likely supports nighttime near-surface foraging, but communication via visual displays is not described for this species in the literature.

Habitat

Open Ocean Deep Sea Seabed/Benthic Coastal
Biomes:
Marine
Elevation: Up to 12139 ft 1 in

Ecological Role

Ectoparasitic mesopelagic predator that removes tissue and blood from large pelagic vertebrates; also an opportunistic predator of small fishes and squid.

Top-down energetic drain on pelagic megafauna (increases prey energy expenditure and can influence behavior/movement via repeated wounding) Creates characteristic cookie-cutter wounds that can serve as entry points for secondary infection and scavenger access, indirectly affecting food-web interactions Energy transfer across depth zones via diel vertical migration (links mesopelagic and epipelagic food webs) Serves as prey for larger sharks and pelagic predators, contributing to mid-trophic energy pathways

Diet Details

Main Prey:
Large pelagic bony fishes Elasmobranchs Marine mammals Cephalopods Small mesopelagic fishes

Human Interaction

Domestication Status

Wild

Cookiecutter shark (Isistius brasiliensis) is a wild, deep-sea shark with no history of domestication or captive breeding. Human contact is accidental (open-ocean bycatch, research) and indirect through circular bite damage to large fish, whales, people and gear. Females ~56 cm, males ~42 cm. Lives in warm oceans, moves up at night, and uses suction to cut 5–7 cm round bites.

Danger Level

Moderate
  • Bite injury: can remove a plug of flesh, producing a circular wound; risk of bleeding and infection if untreated. The species is small (to ~56 cm) but its specialized dentition and suction feeding can cause disproportionate tissue loss.
  • Low encounter probability: typically oceanic and deeper by day, with increased near-surface presence at night due to diel vertical migration; risk is greatest for night-time open-ocean swimmers/divers or people in the water far offshore.
  • Equipment-related hazard: bites to oceanographic gear/lines can create operational risks (not usually direct bodily harm, but may contribute to mission/gear failure scenarios).

As a Pet

Not Suitable as Pet

Legality: Cookiecutter Shark (Isistius brasiliensis): not listed as a pet by law; not sold in the pet trade; usually covered by wildlife and marine capture and transport permits (varies by area). Public aquariums almost never keep it; collection needs scientific permits.

Care Level: Expert Only

Purchase Cost:
Lifetime Cost: $100,000 - $500,000

Economic Value

Uses:
Negative economic impact (depredation/damage) Scientific/research value Incidental bycatch (limited commercial value)
Products:
  • No standard commercial products (not a target species).
  • Indirect costs: circular bite damage ("cookiecutter" lesions) on high-value pelagic fishes (e.g., tunas, billfishes) can reduce market value; also documented biting damage to human equipment/structures (e.g., submarine sonar domes/towed arrays, undersea cables) requiring maintenance/repair.
  • Research/specimen value: studies on bioluminescence (photophores/ventral counterillumination), feeding biomechanics (suction + excision), and oceanic trophic ecology.

Relationships

Predators 5

Bigeye Tuna Thunnus obesus
Yellowfin Tuna
Yellowfin Tuna Thunnus albacares
Swordfish
Swordfish Xiphias gladius
Blue Shark
Blue Shark Prionace glauca
Shortfin Mako
Shortfin Mako Isurus oxyrinchus

Related Species 6

Largetooth Cookiecutter Shark Isistius plutodus Shared Genus
Kitefin shark
Kitefin shark Dalatias licha Shared Family
Spined Pygmy Shark Squaliolus laticaudus Shared Family
Taillight Shark Euprotomicroides zantedeschia Shared Family
Pygmy Shark
Pygmy Shark Euprotomicrus bispinatus Shared Family
Longnose Pygmy Shark Heteroscymnoides marleyi Shared Family

Ecological Equivalents 4

Animals that fill a similar ecological role in their ecosystem

Largetooth Cookiecutter Shark Isistius plutodus Closest niche match: a small mesopelagic dalatiid that uses suction-assisted ectoparasitic biting on large pelagic animals and overlaps in oceanic habitat and vertical migration behavior.
Lamprey
Lamprey Petromyzon marinus Functional analog for feeding mode: attaches by suction and removes tissue and blood from much larger hosts (ectoparasitism), but occurs in temperate coastal and freshwater-connected systems rather than the pelagic deep sea.
Cookiecutter-like dalatiids Dalatiidae Share deep-water/oceanic foraging and dalatiid jaw/tooth specializations for gouging and cutting. However, Dalatias licha is more often predatory/scavenging than a stereotypical cookiecutter ectoparasite.
Small mesopelagic bioluminescent sharks Etmopterus spinax Occupies similar depth bands and uses bioluminescence in the mesopelagic. The ecological similarity is habitat/behavioral (diel vertical migrations), not feeding strategy — Etmopterus is a small predator rather than a plug-biter.

Cookiecutter sharks are squaliform sharks. Squaliform sharks have two dorsal fins. Squaliform sharks usually have five to seven gill slits on their sides. They also typically do not have anal fins.

5 Incredible Cookiecutter Shark Facts

  • These sharks have the largest teeth, in proportion to their body size, of any shark species. Like all sharks, it loses its teeth and grows new ones throughout its life.
  • The liver accounts for 35% of the sharks’ weight. The liver contains low-density lipids that help this shark float.
  • The underside of the shark is covered in photophores that give this shark an eerie green glow. The glow lasts for up to 3 hours after the shark dies.
  • These sharks are parasitic. They often bite out a cookie-shaped hole in a much larger fish.
  • These sharks have bitten through soft areas, like electrical cables and rubber sonar domes of submarines.

Classification and Scientific Name

The scientific name of the cookiecutter shark is Isistius brasiliensis. There are two species of cookiecutter sharks. The Isistius brasiliensis is called the cookiecutter shark, while the Isistius plutodus is called the large cookiecutter shark. They are members of the Isistius genus.

All of these sharks are members of the Dalatiidae family. This family is more commonly referred to as the kitefin shark family. They are also members of the Squaliformes order, which includes over 125 fish species. Like other fish with a spine primarily made of cartilage, they are part of the Chondrichthyes class. They belong to the Chordata phylum and the Animalia kingdom.

Species

Cookiecutter shark (Isistius brasiliensis) caught off Hawaii

There are two species of cookie-cutter shark: Isistius brasiliensis and Isistius plutodus (large cookie-cutter shark).

©PIRO/NOAA Observer Program, Public domain, via Wikimedia Commons – Original / License

There are two species of these sharks. There have been only about 10 largetooth cookiecutter sharks caught, so very little is known about them.

Scientists believe that the largetooth cookiecutter shark has larger teeth, especially on the lower jaw, than the cookiecutter shark. They also think that the largetooth shark is a weaker swimmer than the cookiecutter shark. They both live in diverse locations globally.

Evolution

Like other shark species, experts believe that cookiecutter sharks evolved from ancestors in the Earth’s oceans more than 400 million years ago. They are classified as Dalatiidae, the dogfish shark family, which is a primitive species. Cookiecutter sharks date back at least 100 million years. 

Appearance

Cookiecutter shark

Cookiecutter sharks have long, slender bodies similar to a cigar shape, earning them the nickname ‘cigar shark.’

©Jennifer Strotman / Public Domain – Original / License

These sharks are light brown. It has a long, slender shape, like a cigar, which is why it is often called the cigar shark. This shark has a short, blunt snout and large eyes. It has two spineless dorsal fins and a large caudal fin.

Covering the shark’s underside are photophores. This makes the fish appear to glow when viewed from the bottom. It will continue to glow for about 3 hours after the shark is dead.

Female sharks are larger than males in size. The average male is 14 inches long, while the average female is 16 inches long.

Distribution, Population, and Habitat

cookiecutter

Cookiecutter sharks are listed as “least concern” by the IUCN.

©Karsten Harte / public domain / Wikimedia Commons – Original / License

These sharks are found throughout the world. Their habitat is coastal areas near islands, typically warm, deeper waters during the day, keeping below 1000 meters in day hours, but have been found as deep as 3,500 meters. They migrate to more shallow waters at night at a depth of around 300 meters.

The International Union for Conservation of Nature lists this species as a species of least concern. There are no accurate numbers of how many of these sharks are in locations around the world.

Predators and Prey

Bigfin reef squid

A cookiecutter shark can swallow a squid whole.

©iStock.com/kororokerokero

The cookiecutter shark will prey on almost any living marine creature. It closes its suctorial lips against the prey, kind of like kissing it. Then, it uses its upper pointed teeth and powerful jaws to grip the prey better. Finally, it uses its upper teeth and jaws to take a chunk out of the animal. Most bites from the teeth and jaws measure about 2 inches across and 2.75 inches tall.

Many different animals have been spotted with this shark’s marks on their bodies, including porpoises, dolphins, whales, seals, sharks, stingrays, and bony fish.

Additionally, these sharks have eaten squid as big as themselves. They swallow these animals whole.

Reproduction and Lifespan

Scientists are not sure how long the gestation period is in these sharks. A shark baby is called a pup. They live inside the mother’s uterus. Six-to-12 pups are born at the same time, with each one measuring between 5.5 and 5.9 inches long when they are born. Each baby is in a sizable sac, so scientists theorize that this shark has a long gestation period.

Even though they may end up with a piece of their bodies missing, some animals eat these sharks. These animals include bony fish and sharks that are larger than they.

Fishing and Cooking

Except for a few caught accidentally, these sharks are not targeted by recreational or commercial anglers.

Population

No one has an accurate count of the number of these sharks.

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Sources

  1. Fishbase / Accessed July 3, 2021
  2. We Love Sharks / Accessed July 3, 2021
  3. Wikipedia / Accessed July 3, 2021
  4. Mentalfloss / Accessed July 3, 2021
  5. Wonderopolis / Accessed July 3, 2021
  6. Florida Museum / Accessed July 3, 2021
  7. Shark Keeper / Accessed July 3, 2021
Abby Parks

About the Author

Abby Parks

Abby Parks has authored a fiction novel, theatrical plays, short stories, poems, and song lyrics. She's recorded two albums of her original songs, and is a multi-instrumentalist. She has managed a website for folk music and written articles on singer-songwriters, folk bands, and other things music-oriented. She's also a radio DJ for a folk music show. As well as having been a pet parent to rabbits, birds, dogs, and cats, Abby loves seeking sightings of animals in the wild and has witnessed some more exotic ones such as Puffins in the Farne Islands, Southern Pudu on the island of Chiloe (Chile), Penguins in the wild, and countless wild animals in the Rocky Mountains (Big Horn Sheep, Mountain Goats, Moose, Elk, Marmots, Beavers).
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Cookiecutter Shark FAQs (Frequently Asked Questions)

A cookiecutter shark is a shark that looks like a cigar that is about 14-22 inches long. These sharks are unique because they bite marine life that is much bigger than themselves. When they bite, they leave a distinctive cookie-cutter shape.

View Cookiecutter Shark Photos