Stingrays are marine animals distinct for their flattened, disc-shaped bodies and long, whip-like tails that often contain a venomous barb. As cartilaginous fish, they are closely related to sharks, sharing a skeletal structure made of cartilage instead of bone. They are found globally in coastal tropical and subtropical marine waters, with some species also inhabiting freshwater rivers and the deep ocean. Most stingrays are benthic, meaning they spend the majority of their lives on the seafloor, often burying themselves in the sand for camouflage and to ambush prey. While many are solitary bottom-dwellers, certain species do travel in groups.
Grouping Behavior and Terminology
Stingrays do aggregate, with certain species being well-known for their large-scale social movements. While many species are predominantly solitary, others, such as the cownose ray and the spotted eagle ray, regularly form groups. These gatherings are not always true schooling, which implies coordinated movement over long periods, but are often transient aggregations where many individuals gather in the same location.
A large group of stingrays is sometimes referred to as a “fever.” This term suggests the high level of activity that occurs during mating or intense feeding. These masses of rays can be visually stunning, especially when they move through shallow coastal waters or migrate in huge numbers. Some species, like certain eagle rays, may form groups that number in the thousands, sometimes up to 10,000 individuals.
The size of these groups can vary widely, from small, loose associations to dense, coordinated masses. Observing these large aggregations often occurs near coastlines, particularly during predictable seasonal events. This collective behavior is not a constant for all species, but it is a significant part of the life cycle for many of the more migratory rays.
Motivations for Aggregation
The primary reasons stingrays gather in large numbers are biological needs. One common driver for mass aggregation is large-scale migration, which involves seasonal movements to find more favorable environmental conditions. Many stingrays move to warmer waters as temperatures drop, with some species traveling thousands of miles in these groups.
Another motivation is reproduction, leading to mass mating events where rays congregate in specific locations for breeding. For example, round stingrays seasonally gather in certain nearshore areas for a few weeks to mate before dispersing. These reproductive gatherings are intense, temporary periods of high abundance in a localized area.
Localized feeding opportunities can also draw many individuals together, especially when a concentrated food source is available. This is less a coordinated social action and more a shared resource exploitation, resulting in a temporary aggregation of many rays. These gatherings are distinct from their day-to-day foraging and represent a response to an abundance of prey.
Movement Patterns and Habitat
When stingrays are not participating in one of these large aggregations, their typical movements are often solitary or involve only small, loose associations. Their general movement patterns are closely tied to environmental factors, such as daily and tidal cycles. They are known to exhibit behavioral thermoregulation, seeking out deeper, more thermally stable waters when extreme temperature changes occur in the shallows.
Stingrays prefer habitats with sandy or muddy bottoms, as well as seagrass beds and estuaries, which allow them to use their camouflage effectively. Their flattened bodies are adapted for concealing themselves by agitating the sand and hiding beneath a thin layer of sediment. Movements are also influenced by tides, with rays often moving to deeper water during the lowest tides to avoid being stranded in the shallows.