Basking Shark

Overview

The Basking Shark (Cetorhinus maximus) is the world's second-largest fish, reaching impressive lengths while maintaining a generally docile and passive nature. Despite their massive size, these sharks are harmless filter feeders that primarily consume zooplankton by swimming slowly with their enormous mouths held wide open.

Distribution & habitat

This species has a cosmopolitan, circumglobal distribution, inhabiting temperate and boreal waters across both the Northern and Southern Hemispheres. While they are frequently observed feeding near the surface in coastal areas and tidal fronts, they are highly migratory and capable of diving to depths exceeding 1,000 meters.

Appearance

Basking sharks are characterized by a fusiform, streamlined body, a pointed snout, and a lunate (crescent-shaped) tail. Their most striking feature is the set of five exceptionally long gill slits that wrap nearly around the head. They typically exhibit countershading, with a dorsal surface ranging from dark grey to black or brown, and a lighter, dull white or grey underside.

Biology & behavior

These sharks are typically solitary but are known to form large aggregations during the spring and summer months. Recent research has identified complex social behaviors, including the formation of "torus" structures where individuals swim in circular, nose-to-tail patterns, which is believed to be related to courtship. They are highly migratory, often tracking seasonal shifts in plankton abundance.

Feeding

As passive filter feeders, they rely on the pressure of water passing through their mouths to strain plankton through specialized, modified gill rakers. They can filter thousands of tons of water per hour to meet their energetic needs.

Reproduction

Basking sharks are believed to be ovoviviparous, with embryos developing within eggs inside the female until they are born live. Their reproductive cycle is characterized by a very long gestation period, estimated at two to three years.