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whale shark

Scientific name Rhincodon typus
Descriptor Smith
Year of description 1828
IUCN category (World) EN
Family Rhincodontidae
Genus Rhincodon
Rhincodon typus Rhincodon typus
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Introduction

The whale shark, Rhincodon typus, is the largest living shark on the planet. The officially recognized record is 18.5m but an individual of over 20 meters has reportedly been observed.

This migratory and cosmopolitan species is found in the oceans and seas of the tropical and subtropical zone, as well as in warm temperate regions, with the exception of the Mediterranean Sea. Despite its size and weight (up to around 40 tons), it is completely harmless to humans.

Heavily fished worldwide until the 1990s, the population of whale sharks has sharply declined during the 20th century. It is estimated to have halved over the last 75 years. Due to the species still being relatively unknown, especially its reproductive cycle, effective conservation efforts are challenging to implement.

Despite being listed on Appendix II of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES), the whale shark continues to be fished, often illegally, in several regions of the world. The species is known for the quality of its meat but is also used in various traditional medicines.

The population off the coast of Mexico, one of the most well-known and studied, is estimated at 2,000 individuals and is a major tourist attraction.

Who is it?

Morphology

  • Type
    shark
  • Average size
    1000 cm
  • Maximum size
    1800 cm
  • Longevity
    80 year
  • Pattern
    ponctuations
  • Type
    shark
  • Average size
    1000 cm
  • Maximum size
    1800 cm
  • Longevity
    80 year
  • Pattern
    ponctuations

How to recognize the whale shark ?

Like other sharks, it is a cartilaginous fish. It has an elongated and massive body. Despite records of over 18m, this shark typically measures around 10m as an adult.

The whale shark's body is two-tone, with a gray to bluish back and a white or yellowish belly. It has vertical stripes on its back and sides, as well as white or yellow spots resembling a checkerboard pattern.

It lacks dorsal and anal fins. The mouth is wide and flat, transverse in front of the eyes, and covered in numerous tiny teeth. It can reach up to 2 meters wide. Over time, it has evolved to resemble a kind of sieve for filtration.

Behaviour & Life cycle

  • diet
    planctophage
  • Sociability
    living in a group or alone
  • territorial
    No
  • Way of living
    diurnal

Of migratory nature, the whale shark can be found alone or in groups of up to a hundred individuals (at least). It is often accompanied by pelagic fish, particularly mackerel that act as cleaner fish. It moves slowly, both near the surface and in deep waters.

It feeds on plankton but also on small fish (sardines, anchovies, young tuna, mackerel...), small crustaceans, and squid. To feed, it assumes a vertical position with its head near the surface. During zooplankton feeding, it makes rapid head rotations with part of it out of the water. The mouth can be opened and closed up to 28 times per minute to carry out the filtration process.

This species returns to the same sites each year to reproduce. Its longevity is estimated to be over 80 years.

Reproduction

  • Reproduction
    ovovivipare
  • Migratory species
    Yes

The whale shark is likely an ovoviviparous species but there are uncertainties about the mechanics of its reproduction. It appears that part of the gestation and birth of the young takes place in very deep water.

The female can carry up to 300 embryos (one specimen has been discovered). They are attached to the yolk inside the egg and can measure around fifty centimeters. Once the yolk is absorbed, the larvae measure about sixty centimeters.

Harmless species

This species does not represent any particular threats to humans when encountered in its natural environment.

Where to find it?

Conservation status of populations (IUCN)

World : EN

Geographic distribution & Conservation

It seems that the Atlantic populations are relatively isolated from their counterparts in the Indo-Pacific region. Whale sharks periodically gather in various known sites around the world.

A study has shown that some populations come to the coastal waters of Ningaloo Reef, Western Australia between March and June. Several individuals have been tracked using tags. They all traveled northeast into the Indian Ocean after leaving the reef.

They stayed in coastal and offshore habitats and made vertical migrations many times, sometimes to depths of over 980 m. Between deep waters and the surface, the temperature changes by around twenty degrees, ranging from a maximum of around 29°C to a minimum of about 4°C.

The effects of tourist pressure are still poorly understood, but studies indicate that it may impact the behavior of these large fish.

What is its habitat?

Natural environment characteristics

  • Temperature
    18 - 30 °C
  • Depth
    0 - 1928 m
  • Environment
    Active pelagic

Biotope presentation

The whale shark is generally observed in offshore waters but can approach coastlines and sometimes enter lagoons and coral atolls. It has also been reported in shallow waters, near estuaries and river mouths, especially during seasonal shrimp births.

Species of the same biotope

To go further

To read on the web

BioObs fishbase EOL UltraMarina

Sources & Contributions

Participation & Validation

The Fishipedia team and specialist contributors are committed to providing high-quality content. However, although the information comes from scientific sources or testimonials from specialists, the cards may contain inaccuracies.

Benoit Chartrer

Benoit Chartrer

Translation

Translation done with the valuable contribution of our translators, who make this information available to a wider audience. We sincerely thank them for their commitment.

Bibliographic references

Movements of whale sharks (Rhincodon typus) tagged at Ningaloo Reef, Western Australia - S.G. Wilson - J.J. Polovina - B.S. Stewart - M.G. Meekan - Marine Biology - 2006.

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