Electric Fields Generated by Monotreme Prey Species.

1998 ◽  
Vol 20 (2) ◽  
pp. 171
Author(s):  
J.E. Gregory
Keyword(s):  
Electric Fields ◽  
Muscle Activity ◽  
Prey Species ◽  
Tap Water ◽  
Prey Detection ◽  
Potential Prey ◽  
Electrosensory System ◽  
Invertebrate Species ◽  
Close Range ◽  
Prey Items

The electric sense of the platypus may be used for the detection of prey, as may the similar but less elaborate electrosensory system in the echidna. However, for neither animal has this been shown directly. In this study, further support for the feasibility of an electrosensory role in prey detection was sought by determining whether potential prey items of either animal generate electric fields with appropriate characteristics. Prey items were placed in tap water and recordings made with a pair of electrodes placed near the specimen. Movement-related electric fields of a few to a few hundred µVcm-1 in amplitude were generated by a number of items including shrimps, fish, earthworms, mealworms and cockchafer larvae. Some recorded potentials were at a frequency consistent with an electromyogenic origin, while others were at a lower frequency and seemed more related to the movements of the animal itself than to the underlying muscle activity. No electric fields could be recorded from several other small invertebrate species tested. It is concluded that the platypus would be able to detect some prey items at close range by sensing the electric fields they generate, but this has not been demonstrated for the echidna.

scholarly journals Electroreception in the obligate freshwater stingray, Potamotrygon motoro

2015 ◽  
Vol 66 (11) ◽  
pp. 1027 ◽  
Author(s):  
Lindsay L. Harris ◽  
Christine N. Bedore ◽  
Stephen M. Kajiura
Keyword(s):  
Electric Fields ◽  
Sensory System ◽  
Voltage Gradient ◽  
Single Family ◽  
Potential Prey ◽  
Freshwater Environment ◽  
Electrosensory System ◽  
High Impedance ◽  
Morphological Adaptations ◽  
Elasmobranch Fishes

Elasmobranch fishes use electroreception to detect electric fields in the environment, particularly minute bioelectric fields of potential prey. A single family of obligate freshwater stingrays, Potamotrygonidae, endemic to the Amazon River, demonstrates morphological adaptations of their electrosensory system due to characteristics of a high impedance freshwater environment. Little work has investigated whether the reduced morphology translates to reduced sensitivity because of the electrical properties of freshwater, or because of a marine-tuned sensory system attempting to function in freshwater. The objective of the present study was to measure electric potential from prey of Potamotrygon motoro and replicate the measurements in a behavioural assay to quantify P. motoro electrosensitivity. Median orientation distance to prey-simulating electric fields was 2.73cm, and the median voltage gradient detected was 0.20mVcm–1. This sensitivity is greatly reduced compared with marine batoids. A euryhaline species with marine-type ampullary morphology was previously tested in freshwater and demonstrated reduced sensitivity compared with when it was tested in seawater (0.2μVcm–1 v. 0.6nVcm–1). When the data were adjusted with a modified ideal dipole equation, sensitivity was comparable to P. motoro. This suggests that the conductivity of the medium, more so than ampullary morphology, dictates the sensitivity of elasmobranch electroreception.

Electric Attraction

Secret Worlds ◽  
2021 ◽  
pp. 85-106
Author(s):  
Martin Stevens
Keyword(s):  
Electric Fields ◽  
Electric Fish ◽  
Weakly Electric Fish ◽  
Chemical Information ◽  
Prey Detection ◽  
Long Distance ◽  
Precise Location ◽  
Small Prey ◽  
Weakly Electric ◽  
Prey Items

This chapter assesses the ability of animals to detect and interpret electric information. While sharks often use chemical information to track down prey from a long distance, many species enlist their electric sense to detect electric cues and determine the prey’s precise location and direct their attacks. Although it is normally used for prey detection, the electric sense can sometimes be used in defence too. The chapter then explores the diversity of ways electricity is produced and used by weakly electric fish. Meanwhile, the platypus can use their electric sense both to avoid objects in the water and to locate small prey items. The echidna also has receptors on the tip of its snout that respond to electric information, but its electric sense seems quite limited. Finally, the chapter considers how bees are able to detect electric fields associated with flowers.

Diet and sexual maturation of the neon flying squid Ommastrephes bartramii during autumn and spring in the Kuroshio–Oyashio transition region

2008 ◽  
Vol 88 (2) ◽  
pp. 381-389 ◽  
Author(s):  
Hikaru Watanabe ◽  
Tsunemi Kubodera ◽  
Taro Ichii ◽  
Mitsuo Sakai ◽  
Masatoshi Moku ◽  
...  
Keyword(s):  
Transition Region ◽  
Sexual Maturation ◽  
Prey Species ◽  
Feeding Strategy ◽  
Ommastrephes Bartramii ◽  
Neon Flying Squid ◽  
The Difference ◽  
Diaphus Theta ◽  
The Kuroshio ◽  
Prey Items

Diet and sexual maturation were examined in the winter–spring cohort of the neon flying squid, Ommastrephes bartramii, during its southward migration through the Kuroshio–Oyashio transition region of the western North Pacific. The main prey items are micronektonic animals and small pelagic fish, which were abundantly distributed throughout the study area. Among the prey species, O. bartramii was dependent on the Japanese anchovy Engraulis japonicus, which also migrate from the northern to southern transition region during the winter, and the micronektonic squid Watasenia scintillans throughout the study period. Other common prey items were Gonatopsis borealis, Diaphus theta, and Ceratoscopelus warmingii from October to November or December, and Tarletonbeania taylori after December. These dietary changes can be explained by the difference in the seasonal north–south migration patterns of the predator and prey species. Male sexual maturation progressed throughout the season, and most individuals were fully mature in January. In contrast, most of the females were immature throughout the study period. The feeding strategy of the squid in relation to their seasonal north to south migration and sexual maturation was discussed.

Predator and prey detection in two species of water bear (Tardigrada)

2019 ◽  
Vol 188 (3) ◽  
pp. 860-864 ◽  
Author(s):  
Harry A Meyer ◽  
Hannah E Larsen ◽  
Nézira O Akobi ◽  
Garret Broussard
Keyword(s):  
Environmental Conditions ◽  
The Other ◽  
Physical Contact ◽  
Nutrient Agar ◽  
Control Treatment ◽  
Prey Detection ◽  
Potential Prey ◽  
Predator Prey ◽  
Petri Dishes

Abstract Tardigrade behavioural studies have focused on responses to abiotic environmental conditions. Predator–prey interactions have received some attention, but not how predators and prey might detect one another. Here, we investigate whether a predatory tardigrade species is attracted to, and a potential prey tardigrade avoids, areas previously occupied by the other. In our experiments, Milnesium lagniappe was the predator and Macrobiotus acadianus the prey. Petri dishes with non-nutrient agar were used as experimental arenas. In one treatment, we allowed Macrobiotus to roam over half of the agar for 20 h, while leaving the other half free of Macrobiotus. We then removed the prey and introduced the predator. In the control treatment, no prey were added. Results indicated that Milnesium individuals were significantly concentrated in the area previously occupied by Macrobiotus, whereas no such concentration was evident when Macrobiotus had not been present. A similar protocol was used to test whether Macrobiotus avoided areas previously occupied by the predator. As expected, Macrobiotus were significantly concentrated in the area never occupied by Milnesium, unlike the control treatment. These results suggest that both species can detect the other without physical contact and react accordingly. Given that the experiments were conducted in darkness, detection is probably olfactory.

scholarly journals Predatory Behavior of Yellow Baboons

Behaviour ◽  
1976 ◽  
Vol 56 (1-2) ◽  
pp. 44-67 ◽  
Author(s):  
Glenn Hausfater
Keyword(s):  
Prey Item ◽  
Prey Species ◽  
Predatory Behavior ◽  
Primate Species ◽  
Papio Cynocephalus ◽  
Vervet Monkeys ◽  
Adult Males ◽  
Lepus Capensis ◽  
Number Of Individuals ◽  
Prey Items

Abstract1. A group of 32 yellow baboons (Papio cynocephalus) in the Masai-Amboseli National Park, Kenya, caught and ate 45 vertebrate prey items during 2519.19 hours of observation. 2. Eighty percent of the prey items were mammals and the most frequently eaten species were African hares (Lepus capensis), vervet monkeys (Cercopithecus aethiops) and neonate gazelle (Cazella granti and G. thomsoni) in that order. The details of predatory behavior for each prey species are described. 3. Rates of predation were significantly higher during the long dry season than during other months of the year, although no correlation was found between total monthly rainfall and monthly rates of predation. A lognormal model however provided a good fit to the monthly rate of predation data suggesting that the rate of predation by Amboseli baboons was affected by several factors that acted multiplicatively with respect to each other and were themselves related to rainfall or dryness. 4. A mean of 2.3 individuals fed directly from the carcass of each prey item. A mean of 3.5 individuals per prey item fed directly or indirectly, i.e., on scraps, from each carcass. In general, both the number of individuals who fed from each carcass and the duration of their feeding bouts was dependent upon the gross body size of the prey item. Adult males fed directly from the carcass of prey items for about three times more minutes than expected from their number in the group; other classes of individuals fed directly from prey carcasses for only one-fourth as many minutes as expected. In general, an adult male would be expected to feed on each category of vertebrate prey at least once per year, while individuals of all other age-sex classes would be expected to feed on most prey categories only once every two years. 5. The most frequent social behavior around prey items was agonistic bouts; no cooperation, simultaneous feeding or specific begging gestures were observed. 6. Estimates of the total number of prey killed annually by Amboseli baboons indicate that baboon predation probably has a negligible effect on prey populations other than vervet monkeys. 7. It is speculated that the need for vitamin B12 underlies baboon predatory behavior, and perhaps that of other primate species as well.

scholarly journals Selective feeding by pelagic fish in the Belgian part of the North Sea

2013 ◽  
Vol 71 (4) ◽  
pp. 808-820 ◽  
Author(s):  
Karl Van Ginderdeuren ◽  
Sofie Vandendriessche ◽  
Yves Prössler ◽  
Hakimu Matola ◽  
Magda Vincx ◽  
...  
Keyword(s):  
North Sea ◽  
Prey Species ◽  
Pelagic Fish ◽  
Horse Mackerel ◽  
Calanoid Copepods ◽  
Oikopleura Dioica ◽  
The North ◽  
Fullness Index ◽  
The North Sea ◽  
Prey Items

Abstract Pelagic fish and their planktonic prey are susceptible to a changing climate, giving rise to mismatches and planktonic bottlenecks. A detailed examination of the feeding ecology of pelagic fish can provide valuable insights in the causes and consequences of these phenomena. The present study investigated the diets of both juvenile and adult herring, sprat, horse mackerel, and adult mackerel in the Belgian part of the North Sea (BPNS) in relation to the distribution of zooplankton and ambient abiotic conditions. A study sampling pelagic fish and zooplankton simultaneously every month during consecutive years, and spanning nearshore to offshore sampling locations, is unprecedented in the southern North Sea. In all, 71 prey taxa were found in 725 stomachs of fish gathered at ten stations, sampled monthly in 2009 and 2010. The proportion of fish with empty stomachs was low (11%), and the number of prey species ranged from 0 to 21 sp. per stomach. The diet of herring and sprat was dominated by calanoid copepods, but herring stomachs also contained many decapod larvae, amphipods, cumaceans, and mysids. Mackerel added sandeels to an otherwise planktivorous diet. Horse mackerel consumed both benthic and pelagic prey. The highest frequency of occurrence in the stomachs was observed for the calanoid copepods Temora longicornis (33 408 of all 55 004 prey items identified) and Centropages hamatus (5003 times found). The fullness index ranged between 0 and 20.6, and averaged highest for sprat (0.86), followed by herring (0.60), horse mackerel (0.26), and mackerel (0.24). We observed a different composition of zooplankton species and life stages in the plankton samples compared with those in the fish stomachs. More adult and female copepods were eaten than the plankton samples would suggest. Also, the calanoid copepod Acartia clausi, the most common calanoid species in the BPNS, was barely eaten, as was the case for fish eggs and larvae, and for common planktonic species known to be preyed upon elsewhere (e.g. Oikopleura dioica, Evadne nordmanni, Euterpina acutifrons). Additionally, plankton densities averaged highest in spring and at midshore (20–30 km from shore) stations, but fullness index was highest nearshore (<12 km from shore) and (apart from sprat) in summer. A significant correlation between fullness index and total density of planktonic prey species was not observed, indicating that zooplankton densities were not restrictive. Yet the fact that more than 100 plankton species occurred in the plankton samples and just two of these (T. longicornis and C. hamatus) accounted for nearly three-quarters of all ingested prey items leads us to conclude that even minor changes in the ecology or phenology of these dominant zooplankters could have profound effects on pelagic fish stocks.

Comparison between the feeding habits of spotted eagle ray (Aetobatus narinari) and their potential prey in the southern Gulf of Mexico

2018 ◽  
Vol 99 (3) ◽  
pp. 661-672 ◽  
Author(s):  
F. Serrano-Flores ◽  
J.C. Pérez-Jiménez ◽  
I. Méndez-Loeza ◽  
K. Bassos-Hull ◽  
M.J. Ajemian
Keyword(s):  
Gulf Of Mexico ◽  
Prey Species ◽  
Prey Availability ◽  
Feeding Habits ◽  
Small Scale ◽  
Potential Prey ◽  
Important Prey ◽  
Ecological Aspects ◽  
Southern Gulf Of Mexico ◽  
Spotted Eagle Ray

In the southern Gulf of Mexico, the spotted eagle ray (Aetobatus narinari) is the second most frequently caught batoid in small-scale fisheries off Campeche. Ecological aspects of this ray are unknown in this region, hampering the understanding of the relationship between its distribution and prey availability in the fishing area. In order to study the feeding habits of this batoid and characterize its potential prey in the study area, stomachs and intestines of 154 specimens (68 females and 86 males) were analysed. The results indicated that A. narinari near Campeche is a specialist and selective predator that feeds mainly on gastropods (92.7% IRI), with no significant differences in the diet found between sexes, size groups, or between stomach and intestine contents. In addition, the results indicated that the most important prey species in the diet were among the most common benthic species in three of the four sampling transects positioned in or adjacent to fishing areas for rays. These most important prey species were Strombus pugilis (53.33% IRI) and Americoliva reticularis (25.6% IRI). Other prey species included Lobatus costatus (5.6% IRI) and Petrochirus diogenes (3.6% IRI). This study suggests that this widely distributed ray species feeds in Campeche's coastal waters and that the study of its potential prey increases the understanding of ecological aspects of the species, which emphasizes the added importance of monitoring fishery impacts on prey species (e.g. the conch fishery off Campeche) to help support integrated assessment and management of fisheries.

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