The bumphead sunfish, known scientifically as Mola alexandrini, is a remarkable marine creature known for its immense size and unusual appearance. This species belongs to the Molidae family, which includes some of the largest bony fish in the world. Found in various ocean environments, this fish presents a unique profile.
Distinctive Features and Size
The bumphead sunfish is recognizable by its massive, flattened body. Some specimens have been recorded at lengths of up to 3 meters (10 feet) and weights exceeding 2,300 kilograms (5,071 pounds), making it the heaviest known bony fish. A particularly large individual found near the Azores in 2021 weighed 2,744 kg (6,049 lb).
This fish features a prominent, bulbous forehead, which gives it the “bumphead” name, and a chin bump. Its skin is thick and leathery, characterized by a grayish-brown color that often includes pale blotches. The body is covered in small, rectangular scales. Unlike most fish, it lacks a caudal fin, or tail, which is instead replaced by a rounded structure called a clavus.
Habitat and Diet
Bumphead sunfish inhabit temperate and tropical waters across the globe, including the Atlantic, Pacific, and Indian Oceans. These pelagic fish primarily reside in the open ocean but can also be found in coastal areas and near coral reefs. They undertake extensive migrations in search of food and suitable environments.
The diet of the bumphead sunfish mainly consists of soft-bodied organisms, such as jellyfish and salps. They also consume:
Ctenophores
Hydrozoans
Small crustaceans
Brittle stars
Small fish
Plankton
Algae
Mollusks
Their relatively small mouth, with teeth fused into a parrot-like beak, is adapted for consuming these soft prey items. While juveniles often feed in coastal food webs, larger sunfish typically dive deeper to hunt.
Conservation Status and Unique Behaviors
The bumphead sunfish is currently listed as Vulnerable on the IUCN Red List. Overfishing is a concern, as these fish are often caught unintentionally as bycatch. Habitat degradation and climate change also contribute to population decline.
Beyond their physical traits, bumphead sunfish exhibit distinctive behaviors. They propel themselves through the water by moving their dorsal and anal fins in a synchronized, back-and-forth motion. Adults are typically observed alone or in pairs, though occasional groups have been reported. These fish can dive to depths of up to 700 meters (2,300 feet). They are also known to bask on their sides near the surface, a behavior thought to help them rewarm after deep dives into colder waters, replenish oxygen stores, and attract gulls to remove parasites from their skin.