Calanoid copepod escape behavior in response to a visual predator (original) (raw)
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Swimming and escape behavior in two species of calanoid copepods from nauplius to adult
Journal of Plankton Research, 2013
Subject to high predation risk, all developmental stages of copepods depend on evasive behaviors for survival in pelagic environments. Swim and escape behaviors were investigated in copepods from early nauplius to adult using 3D high-speed micro-cinematography. Parvocalanus crassirostris and Eurytemora affinis are two common estuarine species with broad geographic ranges. The early naupliar stages were mostly immobile, whereas the copepodids and adults spent most of the time actively swimming. Escapes and/or behavioral freezes were elicited by a predator mimic, an abrupt hydromechanical stimulus created by the rapid vertical movement of a 3-mm sphere, and video-recorded at 500 frames-per-second. All developmental stages of planktonic copepods responded with evasive behaviors and responses decreased with distance from the sphere. Maximum response distances were greater and response latencies were shorter in copepodids than in nauplii. Maximum escape speeds increased with copepod size, while the duration of the escape response decreased with the developmental stage. Maximum escape speeds scaled to body length as a power function from early nauplius to adult. Species-specific patterns in escape trajectories were apparent at the first nauplius (N1). These results start to differentiate between performance differences that result from size and design constraints, and those that are due to species-specific behavioral patterns.
Marine Ecology Progress Series, 1998
We investigated the vulnerability of 2 copepod species (Eurytemora affinis and Temora longicornis) to predation by predators with different foraging modes, three-spined stickleback Gasterosteus aculeatus juveniles and mysid shrimps Neomysis integer. Copepods were videofilmed escaping from predators and from an artificial flow field, and the results were used in a model of hydrodynamic disturbance generated by a predator The copepods detected mysids from a significantly larger distance than they detected sticklebacks (0 45 and 0.24 cm, respectively). Consequently, the capture success of the sticklebacks was higher than that of mysids. In the case of sticklebacks foraging on E. affim-S, copepod reaction distance was significantly correlated with stickleback approaching speed; sticklebacks captured a copepod only if they were able to slowly approach to within a strike distance of <0.1 cm from the prey. Also, there was a major difference between the vulnerabilities of the 2 prey species: the capture success of sticklebacks was 92 % with T. longicornis and 53 % with E. affinis. This corresponded with experiments with artificial flow, where the threshold fluid velocity gradient eliciting an escape response in copepods was 4 times higher in T, lonqicornis than in E, affjnis (8.2 and 2.1 S-', respectively). The hydrodynamic model accurately predicted the positive relationship between stickleback approaching speed and copepod reaction distance, as well as the difference between the 2 copepod species. This suggests that, by using simple artificial flow experiments, we can rank various zooplankton species according to their escape capabilities, and thus predict their vulnerability to predation by small fish with different motility patterns. In contrast, the model did not conform with observations on mysids. Apparently, the hydrodynamic disturbance created by a mysid is not related to its swimming speed, but to some other factor, such as the beat rate of swimming appendages. KEY WORDS: Predation vulnerability. Escape response. Hydrodynamic signals. Prey selection Eurytemora affinis. Temora longicornis. Gasterosteus aculeatus. Neomysis integer
Adaptive Behavior, 2011
Copepods are important grazers on microplankton in marine food webs and are, in turn, preyed upon by a wide range of predators with diverse feeding adaptations. Although copepods have evolved numerous adaptations to help them avoid predation, their escape behavior sets them apart from many other planktonic organisms. Mechanoreception is widely used by copepods to detect hydrodynamic disturbances created by approaching predators. When these disturbances are detected, copepods respond quickly with escape jumps that can accelerate them from a stationary position to speeds of over 600 body lengths per second within a few milliseconds. Myelinated nerves may improve the escape behavior of some copepods through faster conduction of nerve impulses. The differences in response latencies between myelinate and amyelinate copepod species are greatest in larger copepod species, where nerve signals must be conducted over longer distances. Environmental variability such as turbulence may affect th...
Sensory-Motor Systems of Copepods involved in their Escape from Suction Feeding
Integrative and comparative biology, 2015
Copepods escape well by detecting minute gradients in the flow field; they react quickly, and swim away strongly. As a key link in the aquatic food web, these small planktonic organisms often encounter suction-feeding fish. Studies have identified certain hydrodynamic features that are created by the approach of this visual predator and the generation of its suction flow for capturing food. Similarly, studies have identified certain hydrodynamic features that evoke the evasive response of copepods. This is a review of the copepod sensory motor system as pertains to understanding their response to suction-feeding fish. Analyses of the reaction time, threshold sensitivity, structure of sensors, and evasive behavior by this key prey of fish can be useful for evaluating the effectiveness of feeding tactics in response to suction flow. To illustrate, we present results comparing a copepod from a fishless lake (Hesperodiaptomus shoshone) to a copepod from a rich fishing ground (Calanus fi...
Prey capture in Clausocalanus furcatus (Copepoda: Calanoida). The role of swimming behaviour
Marine Biology, 2008
Prey capture is a fundamental process for the success of copepods in food-diluted environments. This process is influenced by several factors, including swimming and predatory habits. This work is aimed at characterising the kinematic and fractal properties of the swimming trajectories and reconstructing the predatory horizon of the small calanoid copepod Clausocalanus furcatus. Results indicate that the motion of C. furcatus resembles a random process, mainly evolving in one direction, whereas its predatory horizon is confined to a small region frontal to the anterior end of the copepod. These outcomes are discussed in terms of specific adaptation taking into account the natural conditions experienced by C. furcatus in its environment.
Marine Biology, 2011
Paraeuchaeta norvegica (8.5 mm total length) and yolk-sac stage Atlantic cod larvae (4 mm total length) (Gadus morhua) larvae were observed in aquaria (3 l of water) using silhouette video photography. This allowed direct observations (and quantitative measurement) of predator-prey interactions between these two species in 3-dimensions. Tail beats, used by cod larvae to propel themselves through the viscous fluid environment, also generate signals detectable by mechanoreceptive copepod predators. When the prey is close enough for detection and successful capture (approximately half a body-length), the copepod launches an extremely rapid high Reynolds number attack, grabbing the larva around its midsection. While capture itself takes place in milliseconds, minutes are required to subdue and completely ingest a cod larva. The behavioural observations are used to estimate the hydrodynamic signal strength of the cod larva's tail beats and the copepod's perceptive field for larval fish prey. Cod larvae are more sensitive to fluid velocity than P. norvegica and also appear capable of distinguishing between the signal generated by a swimming and an attacking copepod. However, the copepod can lunge at much faster velocities than a yolk-sac cod larva can escape, leading to the larva's capture. These observations can serve as input to the predator-prey component of ecosystem models intended to assess the impact of P. norvegica on cod larvae.
Copepod sensitivity to flow fields: detection by copepods of predatory ctenophores
Marine Ecology Progress Series, 2006
Copepods have the mechanoreceptive abilities to detect velocity gradients generated by approaching predators and the ability to respond to these predators within milliseconds. Ctenophores produce a low-velocity feeding current to entrain slow-swimming and non-motile prey. Since copepod species vary in their sensitivity to hydrodynamic disturbances, it is possible that species will differ in their ability to distinguish flow-generating ctenophores from the surrounding fluid. Predatorprey interactions were recorded between the ctenophore Mnemiopsis leidyi and 3 copepod species, Acartia tonsa, Paracalanus parvus and Temora turbinata. Although A. tonsa is more sensitive to hydrodynamic disturbances, T. turbinata was most successful in escaping the ctenophore predator. T. turbinata entered the inner lobe area (capture surfaces) of the ctenophore significantly less than either A. tonsa or P. parvus and were better able to escape both encounters and contacts with the inner lobes. These results suggest that sensitivity to velocity gradients may play only a minor role in determining escape success and an intermittent swimming pattern may increase susceptibility to capture by flow-generating predators.
High-Speed Video Analysis of the Escape Responses of the CopepodAcartia tonsato Shadows
The Biological Bulletin, 2003
The copepod Acartia tonsa exhibits a vigorous escape jump in response to rapid decreases in light intensity, such as those produced by the shadow of an object passing above it. In the laboratory, decreases in light intensity were produced using a fiber optic lamp and an electronic shutter to abruptly either nearly eliminate visible light or reduce light intensity to a constant proportion of its original intensity. The escape responses of A. tonsa to these rapid decreases in visible light were recorded on high-speed video using infrared illumination. The speed, acceleration, and direction of movement of the escape response were quantified from videotape by using automated motion analysis techniques. A. tonsa typically responds to decreases in light intensity with an escape jump comprising an initial reorientation followed by multiple power strokes of the swimming legs. These escape jumps can result in maximum speeds of over 800 mm s~' and maximum accelerations of over 200 m s~ 2. In .4. tonsa. photically stimulated escape responses differ from hydrodynamically stimulated responses mainly in the longer latencies of photically stimulated responses and in the increased number of power strokes, even when the stimulus is near threshold; these factors result in longer escape jumps covering greater distances. The latency of responses of A. tonsa to this photic stimulus ranged from a minimum of about 30 ms to a maximum of more than 150 ms, compared to about 4 ms for hydrodynamically stimulated escape jumps. Average response latency decreased with increasing light intensity or increasing proportion of light eliminated. Little change was
Light primes the escape response of the calanoid copepod, Calanus finmarchicus
PloS one, 2012
The timing and magnitude of an escape reaction is often the determining factor governing a copepod's success at avoiding predation. Copepods initiate rapid and directed escapes in response to fluid signals created by predators; however little is known about how copepods modulate their behavior in response to additional sensory input. This study investigates the effect of light level on the escape behavior of Calanus finmarchicus. A siphon flow was used to generate a consistent fluid signal and the behavioral threshold and magnitude of the escape response was quantified in the dark and in the light. The results show that C. finmarchicus initiated their escape reaction further from the siphon and traveled with greater speed in the light than in the dark. However, no difference was found in the escape distance. These results suggest that copepods use information derived from multiple sensory inputs to modulate the sensitivity and strength of the escape in response to an increase ri...
Mapping the free-swimming attack volume of a planktonic copepod, Euchaeta rimana
Marine Biology, 2002
The ability of planktonic copepods to detect and pursue remote prey is well documented, but there are no empirical descriptions of their three-dimensional (3D) sensory fields. In this study, the attack volume of females of Euchaeta rimana Bradford, a planktonic calanoid copepod, was mapped by plotting the positions of attacked prey within a standardized 3D coordinate system defined by the body axes of E. rimana. This analysis was performed using videotaped observations of predatory interactions between free-swimming E. rimana and smaller copepod species. Attack by E. rimana was an oriented response, accurately directed toward remote prey within an ellipsoidal volume anterior to its paired first antennules. This attack volume enveloped the large mechanosensory setae projecting anteriorly from the first antennules, with attack distances averaging 1.5 mm, or less than one body length of the predator. E. rimana attacked a larger prey species, Acartia fossae, at significantly longer distances than it attacked a smaller species, Acrocalanus inermi, reflecting prey-specific perceptive volumes. Such perceptual biases may underlie the selective feeding patterns observed in E. rimana and other copepod species. These observations are consistent with mechanosensory mechanisms of prey identification and localization, suggesting that fluid disturbances provide the releasing and directing stimuli for E. rimana during predatory interactions. Electronic supplementary material to this paper can be obtained by using the Springer LINK server located at http://dx.