“Devil fish” is a common name for large, ray-like marine animals with prominent, horn-like fins near their mouths. Despite their imposing appearance, their true nature is not menacing. This article explores their distinct physical traits, marine environments, and relationship with humans.
Identifying Devil Fish
The term “devil fish” primarily refers to species in the Mobulidae family, including Mobula and manta rays. These large cartilaginous fish have flattened, diamond-shaped bodies, typically dark on top and lighter underneath. They possess wide, forward-facing mouths, five pairs of ventral gill slits, and distinctive cephalic fins. These fins, which appear like horns when rolled up, play a role in feeding.
Mobula rays typically have a wingspan up to 3 meters, though some reach 5.2 meters. Larger manta rays include the reef manta ray (Mobula alfredi), with a wingspan of 3 to 4.5 meters, and the giant oceanic manta ray (Mobula birostris), the largest ray species, averaging 4.5 to 7 meters. Some individuals have been recorded up to 9.1 meters. While some Mobula species have a short tail with a small stinger, most manta rays lack these, contributing to their harmless nature.
Life and Habits of Devil Fish
These rays inhabit tropical and subtropical waters globally, frequenting open ocean environments and coastal areas like coral reefs. Their diet consists primarily of plankton and small fish, which they filter from the water using specialized gill rakers.
To maximize feeding efficiency, these rays utilize various strategies. They often swim with mouths agape and cephalic fins unfurled to funnel prey-rich water. Collective behaviors like “chain feeding” (individuals swimming in a line) or “cyclone feeding” (groups forming a vortex to concentrate plankton) are observed. They are also known for graceful swimming motions, powered by their pectoral fins.
Occasionally, these rays perform leaps out of the water, a behavior known as breaching. The exact reasons are not fully understood, but it may relate to communication, courtship displays, or parasite removal. These acrobatic displays, alongside their serene underwater movements, contribute to their role in marine ecosystems.
Devil Fish and Human Interaction
Despite their formidable name and size, devil fish are not considered dangerous to humans. They are not aggressive and pose no threat to divers or swimmers. Their gentle disposition makes them a draw for eco-tourism, with many seeking encounters through diving and snorkeling.
However, human activities present substantial threats to their populations. Targeted fishing for their gill plates is a primary concern, as these are sought for use in some traditional medicine markets. Bycatch, where rays are unintentionally caught in fishing gear, also significantly impacts their numbers.
Many Mobulidae species face conservation challenges. The giant oceanic manta ray (Mobula birostris) is listed as Endangered by the IUCN, while the reef manta ray (Mobula alfredi) is Vulnerable. Other Mobula species are also categorized as Near Threatened, Vulnerable, or Endangered. Their slow reproductive rates, typically one pup every few years, make them susceptible to population declines.