What are basking sharks

Fish dictionary: basking shark (Cetorhinus maximus)

Basking shark
(Cetorhinus maximus)


Basking shark head

The basking shark (Cetorhinus maximus), in English "Basking shark", is the only species of the basking shark family (Cetorhinidae) within the mackerel shark family (Lamniformes).

These include some of the largest and most well-known species of predatory sharks, such as the great white shark, mako shark, and porbeagle sharks.

The basking shark (Cetorhinus maximus) is up to 10 m long and weighs up to around 4 t, making it the second largest known fish on earth after the whale shark.

Like the basking shark, it feeds on plankton.

Around 25 percent of the basking shark's body weight is made up of the oil-containing liver, which enables the animals to be buoyant in the water


The main characteristics of the basking shark:

  • its coloring is almost monochrome dark gray, gray-brown to blackish, with the back being darker than the underside
  • the animals often have light or dark spots on the back and sides of the body, and also below the head
  • The undersides of the fins are also dark gray, but in young animals they are white with a sharp demarcation from the dark areas
  • in very rare cases albinism can occur
  • its pectoral fins are very broad
  • it has two dorsal fins, of which the first clearly surpasses the second and behind the free rear
    At the end of the pectoral fins
  • he also has a pair of pelvic fins, an anal fin that is almost the same size as the second dorsal fin,
    a crescent-shaped caudal fin with broad side keels on the caudal fin stalk and a very
    long upper lobe, while the lower one is slightly shorter (homocercial caudal fin). The fin is clearly notched at the upper tip
  • the snout is conical-pointed and elongated and protrudes far beyond the mouth
  • the numerous and multi-row single-pointed teeth of the upper and lower jaw are very small and curved
  • both the eyes and the spray holes are very small
  • The basking shark's most striking feature, besides its size, is the five pairs of giant gill slits, the
    surround his body behind the head like a collar and almost at the top and bottom of the body
    to meet
  • on the inside the gill arches are equipped with traps made of modified teeth in a mucous membrane,
    which are used for nutrition

Types of confusion: ./.


The basking shark reaches an average body length of 6.70 m to 8.80 m and can max. Up to 10 m, according to
some springs can also be 12 m long. Its maximum weight can be up to 4000 kg.

Maximum age

The basking shark is around 50 years old.

Way of life, habitat, occurrence

Basking sharks are found in both hemispheres. They prefer the cold to moderately warm waters wherever
they follow the respective plankton supply. On the basis of sightings, which usually took place near the coast, their distribution has so far been to the coastal and pelagic areas of the Atlantic Ocean (Newfoundland to Florida, southern Brazil and Argentina, South Africa, the Mediterranean Sea, the North Sea, Norway and Iceland) and the Pacific (Japan, Korea, China, the south coast of Australia, New Zealand, Tasmania, Chile, Peru, Ecuador and the Gulf of California to the Gulf of Alaska).

The sharks also penetrate bays and estuaries in their search for food.


During courtship, the males follow the females to mate with them. Placed when mating
the male puts his pectoral fins over the first dorsal fin of the female while he introduces the clasps into the cloaca.

The rough skin of the partner rubs against each other, which in both sexes leads to abrasions of the skin
parts in the area of ​​the cloaca. Due to the study of scarring in the female vagina
It is assumed that multiple mating with different males occurs in a mating season.

The males' sperm lie in packets, so-called spermatophores, with a diameter of about
3 cm in front. When mating, about 16 liters of sperm are transferred into the female.

The females only have one developed ovary (right) in which the mature eggs are produced. To
upon fertilization, the fertilized egg develops in the uterus of the female.

The pregnant females separate from the shark groups and move away from the coastal waters. A gestation period of more than 1 year is assumed.

As a rule, females that are not yet sexually mature and not pregnant are caught and significantly more frequently
sighted as pregnant females, and also the relationship between males and females is clearly shifted in the direction of the females.

Basking sharks give birth to live cubs that hatch from eggs that have been incubated in the womb and are already forming
open before birth; they are thus ovoviviparous.

Before birth, the young probably feed on the oophagus, i.e. on the mother's unfertilized eggs. Whether it
in the basking shark the adelphophagy known from related shark species is not known.

The litter consists of a few young animals, but so far only one litter with 6 young animals has actually been documented.
mentions. Newborn basking sharks are likely to be 1.5 to 1.8 meters in length.

The slowly growing animals reach sexual maturity at a body length of 5.70 m
for males and 8 meters for females.


The basking shark, like the whale shark, feeds on zooplankton, i.e. small animal organisms that live in the
floating in free water (especially small crustaceans, pteropods, fish eggs and larvae). To eat it often swims near the surface of the water and, with its mouth wide open and slowly swimming, filters the plankton from the water, which gets caught in the gills and is then swallowed.

The small crustaceans and other plankton organisms get caught in the mucus-covered caster teeth and
are washed into the throat when the mouth is closed. With this method the basking shark is able to get round
To filter 1,800 t of water per hour for food, whereby a fully grown basking shark needs up to 500 liters of zooplankton for nutrition per day.

The pots are thrown off at regular intervals of around 4 to 5 months and replaced with new ones. It is unclear whether this goes hand in hand with a shark fasting period, during which the animals retreat into deeper water layers.

The assumption that the animals have a kind of 'hibernation' in the phase in which they renew their gill pots has, however, been refuted.

A 3-year study by the Marine Biological Association in Plymouth in 2002, with a total of
21 basking sharks were equipped with satellite transmitters, was able to show that when searching for food they cover large distances in the open sea and in doing so reach a water depth of over 700 m.

Occasionally they even cross the equator on the up to 9,000 km long stretches and are extremely active during the winter months, according to a study by the Massachusetts Division Of Marine Fisheries in 2009.

While they look for food near the surface in summer, they follow the plankton swarms in the months from November to March to greater depths below the continental shelf, where large quantities of zooplankton reside at this time.

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