Escape behavior of planktonic copepods in response to hydrodynamic disturbances: high speed video analysis

Abstract

Planktonic copepods exhibit rapid escape behavior in response to hydrodynamic disturbances. Small disturbances of brief duration were produced by a piezoelectric transducer moving a small cylinder. The escape responses of free-swimming adult males and females of the copepods Acartia tonsa and A. lilljeborgii were recorded using high-speed video and quantified using computerized motion analysis techniques. Response latency, swimming speed, acceleration and turning rate during escape behavior were measured. Acartia spp. typically respond within 4 ms to a hydrodynamic disturbance with multiple power strokes of the swimming legs. Each stroke and recovery is of ca. 7 ms duration with maximum speeds often exceeding 500 mm s -1 and minimum speeds between strokes rarely falling below 100 mm s -1 . Acceleration during initial escape usually exceeds 100 m s -2. Escapes often begin with rapid reorientation away from the source of the disturbance, with maximum turning rates of about 30°ms -1 . Significant differences were found between the kinetics of escape responses of adult male and female copepods of each species, with males having greater maximum speeds and accelerations, and females having longer duration jumps. Significant differences were also found between males and females of the 2 species, with A. lilljeborgii exhibiting greater speeds and more rapid acceleration than the smaller A. tonsa.

Morphology of seahorse head hydrodynamically aids in capture of evasive prey

“…This is supported by our data that show that copepods within the strike region have little chance at escape as pivot feeding covers the distance to the copepod in o1 ms (Fig. 3a,b), faster than the 2-4 ms response latency of the copepod 5 . However, although the use of pivot feeding to explain the adaptive significance of head morphology in sygnathid fish 19 is important, one cannot ignore the fact that without the ability to approach evasive prey undetected, short range pivot feeding becomes ineffective.…”

“…Mechanoreception of hydrodynamic disturbances, flow shear (strain), is considered most important for the remote detection and discrimination of predators [7][8][9][10] . Copepods can respond to these hydrodynamic signals within 2-4 ms 5,11,12 and achieve escape speeds over 500 body lengths per second 5,13 .…”

“…Planktonic copepods, a common food source of syngnathid fish 4 , possess powerful and effective escape responses to the approach of predators 5,6 . Mechanoreception of hydrodynamic disturbances, flow shear (strain), is considered most important for the remote detection and discrimination of predators [7][8][9][10] .…”

Danger of zooplankton feeding: the fluid signal generated by ambush-feeding copepods

“…Planktonic copepods, the dominating group of mesozooplankton in the ocean, jump to escape predators (Fields & Yen 1997), to attack prey (Jiang & Paffenhö fer 2008;Kiørboe et al 2009) or to reposition in the water column (Svensen & Kiørboe 2000). While the latter jumps are obviously less powerful than the former (Buskey et al 2002), they may be much more frequent. Thus, ambush feeders typically reposition by jumping upwards every 1 -10 s Titelman & Kiørboe 2003).…”

Dogs lap using acceleration-driven open pumping

“…Archerfish adjust for index of refraction when shooting water jets through the interface to catch prey (1,2), some marine copepods leap into the air to avoid predation (3)(4)(5)(6), and lizards and frogs run or skip across the water surface to escape predators (7)(8)(9). However, almost all terrestrial animals interact regularly with the air-water interface when they drink or feed (10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22).…”