The Ring of Fire's shark gathering
The Banda Sea, a remote body of water in Indonesia's Maluku province, is the site of a large marine event. Each year, between September and November, huge aggregations of scalloped hammerhead sharks (Sphyrna lewini) gather here. This region, part of the volcanically active Ring of Fire, contains deep oceanic trenches reaching depths of 7,000 meters. Seasonal monsoons drive a process called upwelling, which brings cold, nutrient-dense water from these depths to the surface. This phenomenon is believed to attract the sharks, although the precise function of these massive gatherings remains an active area of scientific research.
Divers have documented schools of 80 to 200 scalloped hammerheads at specific sites near islands such as Hatta, Rhun, Ai, and Suanggi. The area is now recognized as an Important Shark and Ray Area (ISRA) because of these recurring aggregations and the presence of this threatened species. The scalloped hammerhead is classified as Critically Endangered by the International Union for Conservation of Nature (IUCN). The species faces significant threats globally from overfishing and the high demand for its fins, which are used in shark fin soup.
A cephalofoil's advantage
The scalloped hammerhead's most distinctive feature is its head, known as a cephalofoil. This wide, flattened structure provides several evolutionary advantages. The placement of the eyes on the outer edges gives the shark exceptional 360-degree vision. The broad surface of the cephalofoil is also covered in sensory organs called ampullae of Lorenzini, which detect the faint electrical fields produced by prey, such as stingrays and other fish hidden on the seafloor.
Unlike the great hammerhead (Sphyrna mokarran), which is typically a solitary species, scalloped hammerheads are known for their social behavior and tendency to form large schools. These sharks are viviparous, giving birth to live young. After a gestation period of around 11 months, a female can deliver a litter of 6 to 42 pups. The discovery and protection of specific habitats, whether for feeding, mating, or schooling, are essential for the survival of this critically endangered predator.