Alopias

Features
By Jordyn Pollock

Diversity

Genus Alopias consists of three species: Alopias vulpinus , Alopias superciliosus , and Alopias pelagicus , all of which are referred to as thresher sharks. A. vulpinus is the most common species and is referred to as common thresher sharks. A. supercilious are referred to as bigeye thresher sharks. Alopias pelagicus are referred to as pelagic thresher sharks. Some other common names of all three species include fox sharks, sea foxes, and swiveltails. Thresher sharks belong to family Alopiidae , order Lamniformes , and phylum Chondrichthyes . These sharks are best known for the extension on the upper lobe of their caudal fins that can grow to over half their body length. Common thresher sharks have falcate pectoral fins that are narrow-tipped and white patches that extend from the mouth to the abdomen around the base of the pectoral fins. Bigeye thresher sharks are known for their large oval eyes and v-shaped ridge on their heads. They possess longer snouts and fewer teeth than common threshers. Pelagic thresher sharks possess a narrower head and longer snout than common threshers with straight pectoral fins.

Geographic Range

Thresher sharks are found worldwide in oceanic and coastal regions of tropical and temperate waters. They can be found as far north as Norway and as far south as the bottom of South America.

Habitat

Thresher sharks can be found in both coastal and oceanic water. Juveniles are most commonly found in coastal areas, while adults are found in deep waters. Thresher sharks are known to inhabit waters up to 1,800 feet (550m) in depth, but they are mostly observed at the surface, breaching the water. Generally, thresher sharks prefer cold, pelagic water.

Systematic and Taxonomic History

Genus Alopias was formerly known as Vulpecula , as named in 1913. The common thresher shark, A. vulpinus , has several synonyms: Squalus vulpinus , Vulpecula marina , Alopias caudatus , and Alopias geryi . A. vulpinus got its current name from Bonnaterre in 1788. Pelagic thresher sharks ( A. pelagicus ) have no synonyms and was named by Nakamura in 1935. Bigeye thresher sharks ( A. superciliosus ) also have no synonyms and was named by Lowe in 1841.

Physical Description

All three species of thresher sharks express countershading, being blue/gray on the dorsal side and white on the ventral side. The dorsal, pectoral, pelvic, and caudal fins are all dark blue/gray on the dorsal side. All thresher sharks have shortened heads with cone-shaped snouts and small mouths. The distinctively long, upper caudal fin lobe of thresher sharks make up almost half the body length of all three species. Common threshers can grow up to 20ft long, while bigeye and pelagic threshers can reach up to 16ft. In all three species, females are longer than males. Bigeye threshers are known for their large oval eyes. They have fewer teeth than common threshers, a longer snout, and a v-shaped ridge on their head. Pelagic threshers have narrower heads and more elongated snouts than common threshers.

  • Sexual Dimorphism
  • female larger

Development

Common thresher sharks develop earlier than other Alopias species. Males are sexually mature when they are 3-6 years old, while females sexually mature when they are 4-5 years old. In comparison, bigeye thresher sharks and pelagic thresher sharks reach sexual maturity much later, around 10-13 years old.

  • Development - Life Cycle
  • temperature sex determination

Reproduction

Common thresher sharks mate in late summer and are ovoviviparous. Common threshers have a gestation period of 9 months and have 4-6 pups. Bigeye threshers have litters of 2-4 pups each year. Pelagic thresher sharks have annual litters of around 2 pups.

Chondrichthyes males possess modified pelvic fins called claspers which they use while mating. Males grab females, holding onto them with their mouths while using the claspers to assist with internal fertilization.

Thresher sharks are ovoviviparous, meaning eggs are fertilized, developed, and hatched within the female. The female then gives birth to live pups. There is no parental investment after pups are born, but the mother must provide some nutrients for hatched pups before they are born.

  • Parental Investment
  • no parental involvement
  • pre-hatching/birth
    • provisioning
      • female

Lifespan/Longevity

In the wild, common threshers can live anywhere between 19-50 years; bigeye threshers can live up to 20 years; pelagic threshers can live up to 16 years, with some females being known to live up to 28 years.

Behavior

Thresher sharks are mainly solitary and all three species of thresher sharks are highly migratory, with the common thresher being circumglobal. Common threshers have a high tolerance for cold waters, and bigeye and pelagic threshers are found in tropical and temperate waters. Thresher sharks are thought to use the long upper lobe of their caudal fin to stun prey when hunting and mostly feed on schooling fish. When hunting schools of fish, threshers often work in groups or pairs. All three species are diurnal, meaning they hunt during the day. Thresher sharks mate via internal fertilization, wherein males insert a clasper into the female’s cloaca. Thresher sharks are believed to mate throughout their ranges annually.

Communication and Perception

All Chondrichthyes species have highly derived sensory organs, using chemoreception, mechanoreception, vision, and electroreception to sense prey. Chemoreception is used to pick up chemicals in the water. Mechanoreception gives thresher sharks the ability to pick up vibrations through the neuromast cells in their lateral line system. The sharks' electroreception techniques utilize their ampullae of Lorenzini to detect electrical signals in the water, such as heartbeats and muscle contractions of prey.

Food Habits

All three Alopias species use their elongated upper caudal fin lobes to stun prey when feeding. Chondrichthyes possess upper jaws that can protract and retract as they open and close their mouths when feeding. Alopias species feed mostly on small schooling species of bony fish, including herrings and mackerels. They are also known to feed on squid.

Predation

Adult Alopias species have no known predators; however, top predators such as larger sharks and killer whales have been known to prey upon juveniles.

Ecosystem Roles

As top predators, Alopias species influence the ecosystem by keeping populations of prey species in check. Without predators, fish species population could boom, causing top-down trophic effects that can negatively influence the entire ecosystem.

Some species of copepods are parasites to thresher sharks, attaching themselves to gill filaments, causing damage and respiration issues.

Economic Importance for Humans: Positive

The International Game Fish Association considers all three species of thresher sharks to be game fish, making them a target species for anglers and an ecotourism asset. The Atlantic common thresher shark fishery in the U.S. is managed by NOAA Fisheries and the Atlantic Highly Migratory Species Division. According to NOAA Fisheries, commercial landings of the Atlantic common thresher sharks totaled 85,600lbs (valued at $38,000) in 2019. In other parts of the world, thresher sharks are caught for their fins, meat, liver, and skin. Thresher sharks also bring in ecotourism income through shark swimming, snorkeling, and scuba diving opportunities.

  • Positive Impacts
  • body parts are source of valuable material
  • ecotourism

Economic Importance for Humans: Negative

There are no adverse effects of Alopias species on humans.

Conservation Status

The IUCN Red List lists bigeye threshers and common threshers as Vulnerable and pelagic threshers as Endangered. All three species are caught as target and bycatch species in pelagic and commercial fisheries. The globally estimated population of bigeye threshers and common threshers has decreased by 30-49%, and pelagic thresher populations have decreased by 50-79% over the last three generations. The U.S. fisheries that capture fresher sharks have set capture limits to help conservation efforts of these species.

Other Comments

Thresher sharks are often referred to as sea foxes, possibly due to their cunning nature.

Encyclopedia of Life

Contributors

Jordyn Pollock (author), Colorado State University, Sydney Collins (editor), Colorado State University.

oriental

found in the oriental region of the world. In other words, India and southeast Asia.

World Map

native range

the area in which the animal is naturally found, the region in which it is endemic.

Ethiopian

living in sub-Saharan Africa (south of 30 degrees north) and Madagascar.

World Map

native range

the area in which the animal is naturally found, the region in which it is endemic.

Neotropical

living in the southern part of the New World. In other words, Central and South America.

World Map

native range

the area in which the animal is naturally found, the region in which it is endemic.

Australian

Living in Australia, New Zealand, Tasmania, New Guinea and associated islands.

World Map

native range

the area in which the animal is naturally found, the region in which it is endemic.

native range

the area in which the animal is naturally found, the region in which it is endemic.

Atlantic Ocean

the body of water between Africa, Europe, the southern ocean (above 60 degrees south latitude), and the western hemisphere. It is the second largest ocean in the world after the Pacific Ocean.

World Map

native range

the area in which the animal is naturally found, the region in which it is endemic.

Pacific Ocean

body of water between the southern ocean (above 60 degrees south latitude), Australia, Asia, and the western hemisphere. This is the world's largest ocean, covering about 28% of the world's surface.

World Map

native range

the area in which the animal is naturally found, the region in which it is endemic.

native range

the area in which the animal is naturally found, the region in which it is endemic.

temperate

that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).

tropical

the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.

saltwater or marine

mainly lives in oceans, seas, or other bodies of salt water.

pelagic

An aquatic biome consisting of the open ocean, far from land, does not include sea bottom (benthic zone).

coastal

the nearshore aquatic habitats near a coast, or shoreline.

ectothermic

animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

polygynous

having more than one female as a mate at one time

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

fertilization

union of egg and spermatozoan

internal fertilization

fertilization takes place within the female's body

ovoviviparous

reproduction in which eggs develop within the maternal body without additional nourishment from the parent and hatch within the parent or immediately after laying.

natatorial

specialized for swimming

diurnal
  1. active during the day, 2. lasting for one day.
motile

having the capacity to move from one place to another.

migratory

makes seasonal movements between breeding and wintering grounds

solitary

lives alone

visual

uses sight to communicate

vibrations

movements of a hard surface that are produced by animals as signals to others

chemical

uses smells or other chemicals to communicate

electric

uses electric signals to communicate

ecotourism

humans benefit economically by promoting tourism that focuses on the appreciation of natural areas or animals. Ecotourism implies that there are existing programs that profit from the appreciation of natural areas or animals.

carnivore

an animal that mainly eats meat

piscivore

an animal that mainly eats fish

References

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To cite this page: Pollock, J. 2022. "Alopias" (On-line), Animal Diversity Web. Accessed {%B %d, %Y} at https://animaldiversity.org/accounts/Alopias/

Last updated: 2022-27-22 / Generated: 2025-10-03 00:55

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