Implications of the feeding current structure of Euchaeta rimana , a carnivorous pelagic copepod, on the spatial orientation of their prey (original) (raw)
Related papers
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.
Bulletin of Marine Science -Miami-
This examination showed how the sexual dichotomy in morphology and feeding was reflected in the swimming behavior of Euchaeta rimana. Nonrandom swimming was clearly exhibited by this copepod, and the evolutionary reasons for the behaviors involve the dual requirements of encountering food and mates. Mechanoreceptive females, with their enlarged feeding appendages and elongated antennal setae, must find prey to feed. Non-feeding males, with reduced mouthparts and antennal setules, must find females to inseminate before exhausting their lipid reserves which were accumulated during juvenile stages. Directional swimming by the female predatory copepod supports the predictions of models in which encounter rate was maximized by swimming orthogonally to their mates and their prey. The female swam horizontally in a turn-and-search pattern to intersect the male which swam vertically in a swim-up-and-sink pattern. Adult female copepods (~2.5 mm prosome length) generally swam smoothly and continuously at an average swimming speed of7 mm's-I , with their antennae oriented into the flow not disturbed by their own movements. Besides mating, females also must find and capture prey. Analysis of swimming by one potential prey, Acartia fossae, showed that these smaller copepods darted up and stopped in various directions to counteract sinking due to gravity. This resulted in a strong vertical component to their directionality which increased the likelihood of encounter with the predatory copepod. The dart-and-stop swimming pattern of Acartia fossae may be an alternate mode of escape from a mechanoreceptive copepod, such as Euchaeta. which can not sense prey when they are not moving.
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
Prey Detection and Prey Capture in Copepod Nauplii
PLoS ONE, 2012
Copepod nauplii are either ambush feeders that feed on motile prey or they produce a feeding current that entrains prey cells. It is unclear how ambush and feeding-current feeding nauplii perceive and capture prey. Attack jumps in ambush feeding nauplii should not be feasible at low Reynolds numbers due to the thick viscous boundary layer surrounding the attacking nauplius. We use high-speed video to describe the detection and capture of phytoplankton prey by the nauplii of two ambush feeding species (Acartia tonsa and Oithona davisae) and by the nauplii of one feeding-current feeding species (Temora longicornis). We demonstrate that the ambush feeders both detect motile prey remotely. Prey detection elicits an attack jump, but the jump is not directly towards the prey, such as has been described for adult copepods. Rather, the nauplius jumps past the prey and sets up an intermittent feeding current that pulls in the prey from behind towards the mouth. The feeding-current feeding nauplius detects prey arriving in the feeding current but only when the prey is intercepted by the setae on the feeding appendages. This elicits an altered motion pattern of the feeding appendages that draws in the prey.
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...
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.
Prey perception in feeding-current feeding copepods
Limnology and Oceanography, 2016
We reply to the comments of Paffenh€ ofer and Jiang (2016) who argues that remote chemical prey perception is necessary for feeding-current feeding copepods to fulfill their nutritional requirements in a dilute ocean, that remote chemical prey detection may only be observed at very low prey concentrations, and that chemical prey perception is feasible if prey cells release dissolved organic material in short-lasting but intense bursts. We demonstrate that mechanoreception at a very short range is sufficient to sustain a living, even in a dilute ocean. Further, if chemoreception requires that prey cells have short intense leakage burst, only a very small fraction of prey cells would be available to the copepod at any instance in time and, thus would be inefficient at low prey concentration. Finally, we report a few new observations of prey capture in two species of copepods, Temora longicornis and Centropages hamatus, offered a 45-lm sized dinoflagellate at very low concentration. The observed short prey detection distances, up to a few prey cell radii, are consistent with mechanoreception and we argue briefly that near-field mechanoreception is the most likely and common prey perception mechanism in calanoid copepods.
Calanoid copepod escape behavior in response to a visual predator
Marine Biology, 2006
Calanoid copepods typically exhibit escape reactions to hydrodynamic stimuli such as those generated by the approach of a predator. During the summers of 2000, 2001 and 2004, two small calanoid species, Temora turbinata Dana, 1849 and Paracalanus parvus Claus, 1863 were exposed to a visual predatory Wsh, the blenny Acanthemblemaria spinosa Metzelaar, 1919, and their predator-prey interactions were recorded using both high-speed and standard videographic techniques. Copepod escape reaction components, including swimming pattern, reactive distance, turning rate, and jump kinetics, were quantiWed from individual predation events using motion analysis techniques. Among the observed escape reaction components, diVerences were noted between the species' swimming patterns prior to attack and their response latencies. Temora turbinata was a continuous cruiser and P. parvus exhibited a hop-and-sink swimming pattern. During periods of sinking, P. parvus stopped beating its appendages, which presumably reduced any self-generated hydrodynamic signals and increased perceptual abilities to detect an approaching predator. Response latency was determined for each copepod species using a hydrodynamic stimulus produced by a 1 ms acoustic signal. Response latencies of T. turbinata were signiWcantly longer than those of P. parvus. Despite some apparent perceptual advantages of P. parvus, the blenny successfully captured both species by modifying its attack behavior for the targeted prey.