Ballistic Beloniformes attacking through Snell's Window

Abstract

Needlefishes (Beloniformes) were observed employing a range of stalking and attacking behaviours to attack schools of bait fishes ranging from the use of tactics common to predatory fishes to a novel behaviour: the use of leaping, aerial attacks. These aerial attacks are suggested to serve two purposes: to extend the attack range of the needlefishes and to reduce their prey's potential for evasion. Furthermore, a third purpose is hypothesized that the needlefishes are taking advantage of Snell's Window, an optical effect which may mask their approach to their prey.

Traumatic Neck Injury: An Accidental Impalement by a Needlefish

“…Needlefish are silver in color with an elongated body and are tubular in shape, ranging from small to medium size; most needlefish are usually between 3 and 95 cm. 6 Needlefish have a characteristic narrow, pointed jaw with numerous sharp teeth. They belong to the family Belonidae and order Beloniformes.…”

“…They belong to the family Belonidae and order Beloniformes. 6 Usually, needlefish swim near the surface; however, if they are startled, frightened, or attracted to bright light, especially at night, they may leap from the water or skip on the surface. They are capable of making short jumps out of the water at up to 65 km•h -1 (40 mph).…”

“…They are capable of making short jumps out of the water at up to 65 km•h -1 (40 mph). 6 With high velocity, their sharp beaks can spear swimmers, divers, or fishermen, inflicting deep puncture wounds. 4,5 In our case, the type of fish was identified based on visual confirmation by the patient and local bystanders who brought him to the hospital.…”

Light pollution of freshwater ecosystems: principles, ecological impacts and remedies

“…For light rays propagating upwards in the water outside the window defined by this angle, total internal reflection will occur (bright red arrows in figure 3a). Snell's window has implications for fish vision and camouflage of on-shore predators [36,37].…”

Oust the louse: leaping behaviour removes sea lice from wild juvenile sockeye salmon Oncorhynchus nerka

“…does not appear to serve this role and often results in slapping contact with the water upon entry (Video S1 in Supporting information). Although some fish leap to catch airborne prey (Day et al ., ) or avoid predators (Eklöv and Persson, ), the diet of sockeye salmon Oncorhynchus nerka (Walbaum 1792) is composed almost exclusively of zooplankton in the water column (Price et al ., ) and in experimental settings juvenile Oncorhynchus spp. typically scatter rather than leap in response to predation threats (Krkošek et al ., ).…”