Depth
Cetorhinus · Sharks & Rays

Basking Shark

Cetorhinus maximus

0-900m
Depth Range
12.0m
Max Size
Mediterranean
Distribution
0-900m
Depth Range
12.0m
Max Size
Pelagic
Habitat
Filter feeder
Diet
Small groups
Social
EN
IUCN Status
Rare
Sighting Likelihood
Kingdom Animalia
Phylum Chordata
Class Elasmobranchii
Genus Cetorhinus
Species maximus

Elasmobranch

Identification & Biology

  • IdentificationThe second-largest fish in the world, with an enormous gaping mouth, gill slits that nearly encircle the head, a pointed snout, and a large crescent-shaped tail. Grey-brown upper body fading to a paler underside. The first dorsal fin is tall and triangular.
  • SizeCommonly 6 to 8 m in the Mediterranean. Maximum recorded length 12.3 m and weight over 4 tonnes.
  • Social HabitCan be solitary but often seen in loose groups of up to 100 individuals during feeding aggregations. Migrates long distances between feeding grounds.
  • HabitatOpen water, typically near the surface when feeding on plankton blooms. Moves along continental shelf edges and into coastal bays seasonally.
  • Depth0 to 900 m. Surface feeding is the most commonly observed behaviour, but satellite tagging has recorded dives beyond 700 m.
  • Feeds OnZooplankton, primarily copepods and fish eggs, filtered from the water column by swimming with the mouth wide open. A passive filter feeder.
  • DistributionWorldwide in temperate and cool-temperate seas. In the Mediterranean, recorded mainly in the western basin, around Sicily, and the Strait of Messina.
  • DescriptionCetorhinus maximus is a gentle giant that poses no threat to humans. Despite its size, it feeds exclusively on tiny planktonic organisms filtered through its gill rakers. Sightings in Maltese waters are rare but documented. The species is listed as Endangered globally by the IUCN, with Mediterranean populations considered severely depleted by decades of accidental capture in fishing nets.

Range

Habitat & Distribution

A seasonal visitor to Mediterranean waters, most often recorded in the western basin. Basking sharks follow plankton blooms and are typically seen at or near the surface in productive coastal waters during warmer months.

Where Malta divers have spotted this species

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Sightings are logged by divers using our What Did You See? dive-log tool. View the full live sightings map.

Detail

Preferred Environment

Favours temperate, plankton-rich surface waters along continental shelves and near thermal fronts where zooplankton concentrates. Despite surface feeding habits, tracking data shows deep dives to several hundred metres between feeding bouts.

Encounter Tips

Best approached slowly and calmly. Avoid casting shadows directly over the animal. Neutral buoyancy and patience increase encounter success significantly.

Basking Shark species card

Biology

Behaviour & Diet

Feeding Strategy

A passive ram filter feeder that swims slowly forward with its mouth wide open, straining zooplankton, fish eggs, and small crustaceans through its gill rakers. Can filter over 2,000 tonnes of water per hour.

Ram filter feeder

Reproduction

Ovoviviparous, with very little known about its reproductive biology. Gestation is estimated at 1-3 years. Litter sizes are thought to be small, and embryos likely practise oophagy.

Ovoviviparous

Behaviour & Defence

Completely harmless to humans despite its immense size. When disturbed, it simply ceases feeding and submerges. Breaching behaviour has been observed but its purpose remains unclear.

Passive giant

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Where to Encounter in Malta

Dive sites where Cetorhinus maximus may be encountered will be added as sighting data is collected.

IUCN Red List Endangered

Conservation Status

This species is assessed as Endangered on the IUCN Red List. Mediterranean populations face ongoing pressure from fishing activity, habitat degradation, and climate-driven changes.

Source: IUCN Red List
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