Prey Caught Research Articles

Skilled forelimb movements in prey catching and in reaching by rats ( Rattus norvegicus) and opossums ( Monodelphis domestica): relations to anatomical differences in motor systems

Traditional anatomical/behavioral classifications suggest that rats and opossums have simple motor systems and are impoverished with respect to their ability to make prehensile movements. Nevertheless, the motor system in rats and opossums represent extremes in relative size and complexity suggesting that a behavioral analysis of the movement competencies of these species will provide insights into the significance of such anatomical differences. This paper examines the movements that the two species use in catching crickets and in reaching for food items. Both species could use a single limb to reach out and grasp prey during prey catching and both could use a single limb to take food from a shelf. Both species could transport the food to the mouth by using a single paw. The food handling behavior of the rats was more complex than that of the opossums, however. They used a variety of prey catching movements and extensively manipulated the prey to remove the legs and wings before eating only the head and body. Additionally the rats made rotatory limb movements of aiming, pronation, and supination, when reaching. For both cricket catching and reaching, they used their digits more than did the opossums. The suggestion also emerged from the results that the movements of the opossums were more fixed and species-typical whereas those of the rats were more plastic and individualistic. Thus, the skilled movements of both species are more complex than is generally recognized and the greater complexity of the rat movements parallels their more complex motor system. These results are discussed in relation to anatomical differences in the motor system and, specifically, to differences in the terminal fields of the pyramidal tract. It is concluded that the motor abilities of nonprimate mammals have been vastly underrated.

A key by which the toad's visual system gets access to the domain of prey

Searching for principles that allow toads to distinguish between prey and nonprey, we wondered how the toad's prey-catching activity measured as R differs in response to changes in significant configurational stimulus features. Elongated shapes moving worm-like in the direction of their longer axes are preferred prey dummies; but a toad is not a worm detector, and a worm is not the unique prey-catching releaser. Considering the frequency distributions of R values, we show that the release of prey catching is in a specific manner sensitive to the relation between the extensions of an object parallel ( xl 1) and perpendicular ( xl 2) to its direction of movement. It is the xl 1, and xl 2 features-relating algorithm that provides the key (instruction) by which the toad's visual system gets access to the domain of potential prey in terms of configurational cues. This, within behaviorally relevant limits, largely invariant algorithm also holds for segmented stimuli. Further investigations show that this principle of object discrimination is not due to experimental procedures but emerges as a species-common property, of which different toad species take advantage in a species-specific manner. Neurobiological correlates are discussed.

Fishing at Rio Grande (Brazil): Ecological niche and competition

This study is an ecological analysis of the use of resources by two potentially competitive groups, the commercial and recreational fishermen of Rio Grande, located on the border of the States of SAo Paulo and Minas Gerais. Tourism at Rio Grande was intensified after the construction of the hydroeletric plant of Marimbondo in 1974, and local fishermen have complained about its interference. Values of niche dimensions, such as fishing periods, grounds, and prey caught were obtained through data gathered at landing points. Local and recreational fishermen usually fish in different parts of the river and catch different fish, because they use different gear. However, in transition months between the wet and dry seasons, when fish are less abundant, there is conflict or competition related to fishing grounds, reinforced by the territorial fishing rights of local longline fishermen in this period. We show how ecological concepts, such as niche and competition, may help to understand strategies of exploitation by human groups, fundamental information for the management of tropical areas.

Nitrogen uptake from prey and substrate as affected by prey capture level and plant reproductive status in four carnivorous plant species.

Uptake of nitrogen from prey and substrate and partitioning of prey-derived nitrogen were studied in the carnivorous plant species Pinguicula alpina, P. villosa, P. vulgaris and Drosera rotundifolia in a subarctic environment. Efficiency in nitrogen uptake from prey was evaluated by tracing 15N from 15N-enriched Drosophila flies fed to the plants. The in situ uptake efficiency differed somewhat between species and ranged from 29 to 41% of prey N. This efficiency was not affected by different feeding levels or plant reproductive status (flowering or non-flowering). A test of the amount of N absorbed from prey caught on flower stalks of Pinguicula villosa and P. vulgaris showed that both species took up little of what was available in prey (2.5% or less). The uptake efficiency found in greenhouse grown plants was higher than in plants in situ (40-50% vs. 30-40% respectively). This could probably best be explained by the absence of rain and a higher temperature in the greenhouse. The prey-derived 15N was traced to reproductive organs and winter buds. Non-flowering individuals allocated 58-97% of the N derived from prey to their winter buds. Flowering individuals allocated 17-43% of the N income from prey to reproduction, while 34-71% were allocated to buds. Root uptake of nitrogen was stimulated by increased prey capture. This increase in uptake of nitrogen from the substrate was larger than the potential direct uptake of nitrogen from captured prey.

Advertisement and Concealment in the Plankton: What Makes a Copepod Hydrodynamically Conspicuous?

Euchaeta rimana, a pelagic marine copepod, roams a 3-dimensional environment and its antennular setal sensors are oriented to detect water-borne signals in 3 dimensions. When the copepod moves through water or moves water around itself, it creates a fluid dis- turbance distinct from the ambient fluid motion. As it swims and hovers, the copepod's laminar feeding current takes the unstable nature of small-scale turbulence, organizes it, and makes the local domain a familiar territory within which signals can be specified in time and space. The streamlines betray both the 3-dimensional spatial location (x, y, z) as well as the time (t) separating a signal caught in the feeding current and the copepod receptor-giving the copepod early warning of the approach of a prey, predator, or mate. The copepod reduces the complexity of its environment by fixing information from a turbulent field into a simpler, more defined laminar field. We quantitatively analysed small-scale fluid deformations created by copepods to document the strength of the signal. Physiological and behavioral tests confirm (a) that these disturbances are relevant signals transmitting information between zooplankters and (b) that hydrodynami- cally conspicuous structures, such as feeding currents, wakes, and vibrations, elicit specific responses from copepods. Since fluid mechanical signals do elicit responses, copepods shape their fluid motion to advertise or to conceal their hydrodynamic presence. When swimming, a copepod barely leaves a trace in the water; the animal generates its flow and advances into the area from which the water is taken, covering up its tracks with the velocity gradient it creates around itself. When escaping, it sheds conspicuous vortices. Prey caught in a flow field expose their location by hopping. These escape hops shed jet-like wakes detected by copepod mech- anoreceptors. Copepods recognize the wakes and respond adaptively.

Trichromatic color vision in the salamander (Salamandra salamandra)

Spectral sensitivity functions were measured between 334 nm and 683 nm in Salamandra salamandra by utilizing two behavioral reactions: the negative phototactic response, and the prey catching behavior elicited by a moving worm dummy. The action spectrum of the negative phototactic response revealed 3 pronounced maxima: at 360–400 nm, at 520–540 nm, and at 600–640 nm. In the range around 450 nm, there was a “reaction gap” where sensitivity could not be measured. The action spectrum of the prey catching behavior was entirely different: maximal sensitivity was found at 500 nm and at 570 nm. Between 500 nm and 334 nm sensitivity decreased continuously for about 1 log unit (Fig. 6).

Role of experience and maturation in barn owl predatory behaviour

Abstract The predatory behaviour on mice by sample of seventeen captive barn owls (Tyto alba) was studied. The owls were divided into two groups according to their age when they entered the Rehabilitation Centre used for this study (either adults/subadults, i.e., with previous predatory experience in the wild, or as fledglings, without any experience of prey catching). The few differences between the behaviour patterns of the age groups suggested that predatory behaviour is mostly under genetic control. While most adult birds caught the mouse, only four young out of eleven studied did so. Both groups showed a decreasing trend in the latency of predation. The young birds were confused or in conflict when facing the prey, and in some cases the owl approached the mouse closely and then returned to the perch to begin a complete predatory sequence again. Three young birds of those that did not hunt were tested six months later. Two of these three young caught a mouse without any evident difficulty. The behaviour displayed by young birds and some patterns indicate that a maturation process is likely influencing the development of the predatory tendency, and do not fully support the hypothesis of the existence of some temporally well‐defined periods.

Projection of Brain Stem Neurons to the Giant Electromotoneurons in the Cervical Spinal Cord of the Electric Catfish <i>Malapterurus electricus</i>

Two giant electromotoneurons located within the cervical spinal cord form the centerpiece of the electromotor system in the electric catfish Malapterurus electricus. The cytoarchitectural organization suggests a high degree of input convergence onto the electromotoneurons. In order to obtain insights into the connectivities of the electromotor system, pre-neurons of the electromotoneurons within the brain stem and the spinal cord were labelled by application of FITC-dextran and horseradish peroxidase onto the surface of a single electromotoneuron. Our results show that the electromotoneurons receive their main inputs from the nucleus profundus mesencephali within the tegmentum and from large neurons of the medial reticular formation. Both nuclei possess an intimate connection to the optic tectum which mediates orientation responses. This pathway to the electromotoneurons could be instrumental in eliciting electric organ discharge during prey catching. The electric avoidance response in turn could be mediated by the Mauthner neurons which are also labelled. In addition to these neurons, cells of the nucleus fasciculi longitudinalis medialis, the descending octaval nucleus and the nucleus funicularis medialis were labelled. As compared to the corresponding neurons in ictalurid catfish, none of these neurons displays any alteration in its general morphology. It is concluded that the evolution of the electric organ from muscle tissue and the development of a central control system of the electromotor response in Malapterurus involved a minimum of alterations in central nervous system circuitry. In contrast to many other electric fishes the electromotor control is mainly accomplished at the level of the electromotoneurons.

Hunting among Moka Bubis in Bioko: dynamics of faunal exploitation at the village level

Hunting by Bubi villages around Moka, Bioko, and their impact on the local prey fauna was studied during July–August, 1992. Questionnaires were sent to 45 known hunters in the region in order to find out their techniques and hunting procedures. Hunting trips were also followed (a total of 204 km covered) and counts of animals brought to the villages from 103 recorded trips were also made. There were two main hunting methods employed: trapping and shooting. Most commonly used was snare trapping. At least five different types were used during the study. Guns were less commonly employed. Both techniques are efficient and productive but prey caught by each method differed. Most animals caught by snares were large rodents (Atherurus africanus, Cricetomys emini) and small antelopes (Cephalophus monticola) whereas those shot were usually antelopes (C. monticola and C. ogilbyi), monkeys (Cercopithecus spp.) and, when accompanied by dogs, drills (Mandrillus leucophaeus). The effects of hunting in the region is acute especially since they incur upon the proclaimed protected areas in the south of the island. Hunting trips are gradually being lengthened and areas which were originally unaffected by this activity are now part of the villages' hunting zones.

Effects of Prey Type, Prey Density and Predator Presence on Behaviour and Predation Risk in a Larval Damselfly

For many animals feeding efficiency trades off against predator avoidance. In laboratory experiments damselfly larvae (Coenagrion hastulatum) changed their behaviour both when a larval dragonfly predator (Aeshna juncea) was introduced, and in response to different prey treatments. The frequency of five «prey catching» behaviours was considerably lower in the presence of a predator when fast swimming Heterocope saliens copepods were used as prey, than, when sedentary Sida crystallina cladocerans were used. I interpret this prey effect as a result of the low encounter rate with Sida prey. The more «general» behaviours walk, abdomen wave, scratch and turn were performed less in the presence of the predator and both prey types. In contrast the behaviours rotate and swim were performed at higher frequencies in the presence of a predator

Adapted and Adaptive Properties in Neural Networks for Visual Pattern Discrimination: A Neurobiological Analysis Toward Neural Engineering

A topic of interdisciplinary research in neurobiology and neuroinformatics concerns visual pattern recognition by neuronal networks. Drawing on quantitative studies of visual releasers of prey catching in toads, it can be shown that moving objects are classified based on an evaluation of certain configurational features. The information regarding these features is provided in the manner of parallel distributed processing within a retino-pretectal-tectal interacting network. This processing structure is, to a considerable extent, modifiable and adaptive. Associative and nonassociative learning processes take advantage of loop operations involving various forebrain structures. An artificial neuronal net, applying some principles of the toad's visual system, is tested to promote the dialogue between neurobiology and engineering.

Functional binocular vision is not dependent on visual experience in the praying mantis.

In vertebrates, it has been shown that binocular visual experience is necessary to develop normal spatial vision. We have investigated whether this is also true for an invertebrate, the praying mantis. The praying mantis is a predatory insect in which prey localization involves the use of binocular disparities. We raised mantids which had one eye occluded throughout development and tested monocular visual fixation and binocular distance estimation in the adult animals. The results revealed that both fixation and prey catching behavior were normally functional in the monocularly reared animals. Thus we conclude that, in mantids, binocular vision is based on a fixed mode of development.

Structure and histochemistry of the epithelia of lips and associated structures of a catfishRita rita

InRita rita the upper lip is associated with the rostral cap and the lower lip with a skin fold. The epithelia of the lips, which are modified with respect to the peculiar feeding behaviour of the fish, are mucogenic. The superficial layer of epithelial cells, in addition to the mucous cells, are involved in active secretion of mucopolysaccharides. Mucus, apart from its diverse functions, as in fish epidermis, lubricates the epithelia giving protection against possible mechanical injury during the searching and catching of prey from bottom debris. Furthermore, the epithelia are thick, an adaptation to their mucogenic nature, so as to provide additional protection. The contents of the club cells are proteinaceous, which correlates with the helical filaments reported in similar cells in fish epidermis. Characteristic ridges on the surface of the lips are considered to be an adaptation to assist in manipulation during the procuring of food. Mucus secreted in the grooves between them reduces friction and prevents the deposition of foreign matter. The skin fold facilitates an increase in gape. The taste buds and ampullary organs, which on the lips and the rostral cap are associated with the localization of prey and triggering of a pick-up reflex, are not located on the skin fold, as the latter often remains concealed between the lower lip and the ventral head skin. The importance of histochemical analysis as a supplement to histological studies is emphasised.

Chemical and Orientational Cues Mediate Selection of Prey Trails by Prairie Rattlesnakes (Crotalus viridis)

KEEN, W. H. 1982. Habitat selection and interspecific competition in two species of plethodontid salamanders. Ecology 63:94-102. LUTHARDT, G., AND G. ROTH. 1983. The interaction of the visual and the olfactory systems in guiding prey catching behaviour in Salamandra salamandra (L.). Behaviour 83:69-79. MADISON, D. M. 1975. Intraspecific odor preferences between salamanders of the same sex: dependence on season and proximity of residence. Can. J. Zool. 53:1356-1361.

Depth utilisation by breeding Ad�lie penguins,Pygoscelis adeliae, at Esperanza Bay, Antarctica

Miniature depth gauges were attached in December 1987 and January 1988 to Adelie penguins,Pygoscelis adeliae, breeding at Esperanza on the Antarctic Peninsula. Results from 34 birds showed that foraging penguins with eggs and with brooded and creching chicks spent mean periods away from the nest of 96, 36 and 21 h, respectively, during which time means of 29.0 h (30%), 11.2 h (31%) and 2.7 h (13%), respectively, were spent under water at depths > 5 m. Time under water was positively correlated with time absent from nest. Maximum depth reached was 170 m but overall birds spent most time at shallower depths. Birds foraging for brooded chicks dived deeper than birds foraging for creching chicks. Stomach-pumping indicated that the principal prey caught at this time was krill,Euphausia superba. Mean mass changes of adults during single foraging trips indicated that krill were caught at a mean rate of 7.2 g min−1 spent under water.

Observations On the Predation Ability of Aporcelaimell Us Nivalis (Altherr, 1952) Heyns, 1966 (Nematoda: Dorylaimida)

Predation by Aporcelaimellus nivalis depended largely on chance encounters with the prey but the pre-feeding attraction and aggregation of up to 7 predators around an already injured prey at a feeding site is an indication of positive perception of prey body fluids. Prey catching and feeding mechanisms comprised five distinct phases viz., encounter with prey, attack response, attack, salivation/extra-corporeal digestion and ingestion/feeding. Rate of predation remained unchanged over a period of eight days but prey number, temperature, agar concentrations, starvation of the predators, type of the prey etc., determined predation. A. nivalis preferred second stage juveniles of Meloidogyne incognita (Kofoid & White, 1919) Chitwood, 1949 and Heterodera mothi Khan & Husain, 1965 to other species of prey nematodes. No predation took place when Hoplolaimus indicus Sher, 1963, Helicotylenchus indicus Siddiqi, 1963 and Hemicycliophora sp. were used as prey; thick cuticle, body annulations and toxic or unfavourable prey secretions were considered the likely cause. Adult (male and female) A. nivalis killing maximum number of prey nematodes was the most active predator stage.

Behavioral Energetics of Overwintering in the Rifleman, Acanthisitta-Chloris

The role of behavioural adjustments in meeting increased daily energy requirements in winter was investigated in rifleman, Acanthisitta chloris, inhabiting lowland forest in South I., New Zealand, by comparing their population density, time-activity budget and foraging behaviour in autumn and winter. Rifleman foraged for 83% of daytime in both seasons. The combined effects on the birds' winter energy budget of increased thermoregulation costs and the shorter daylength for foraging were at least partly offset by an estimated 23-29% decrease in the amount of energy expended daily on activity and a 78% increment in prey caught per day. The reduced energy expenditure on activity resulted from rifleman spending less time on expensive flying and more time roosting. The increase in prey capture rate may have stemmed from a 35% seasonal reduction in the birds' population density and reduced prey mobility at lower ambient temperatures. Marked sexual size dimorphism was not reflected in gender differences in activity budgeting or prey capture rate, but the sexes differed in their relative use of foraging substrates. Rifleman showed few seasonal changes in daily activity rhythm or microhabitat use. The behavioural energetic overwintering tactics of rifleman are compared with those of other Australasian and north temperate zone land-birds.

The Size and Shape of Traps of Utricularia vulgaris L.

An individual of the aquatic carnivorous plant Utricularia vulgaris L. simultaneously bears many traps ranging in size from about 1 to 5 mm long. The traps are dimorphic, one type being in the vast majority. The shape, volume and biomass of majority-type traps conform to scaling relationships that allow various attributes of functional and ecological consequence to be predicted from an easily measured length. Trap size is not a reflection of the duration of development or age since maturity of a trap, since each cohort of traps consists of a range of trap sizes, resulting from differential rates of cell division and expansion. The investment of carbon, nitrogen and phosphorus resources in an individual trap scales with biomass such that about 40 small traps can be produced for the same initial outlay as one large one. Larger traps have a wider aperture and much more capacious lumen than small traps, potentially accommodating larger prey and more of them, but it remains to be discovered whether the benefits due to more prey caught by large traps scale to offset the greater costs of production. Key-words: Carnivorous plant, scaling of traps, Utricularia vulgaris

Preference of Prey Size and Profitability in Barn Owls Tyto Alba Guttata

AbstractBarn owls of the subspecies Tyto alba guttata which had been bred in captivity, and which had experience with prey, were examined for preferences in prey size (weight) under experimental conditions. They were offered a choice of larger and smaller prey of three weight classes (3/10 g; 10/40 g; 40/160 g) either active or inactive (laboratory mice, Mus musculus; laboratory rats, Rattus norvegicus). The frequency of choices of smaller prey increased significantly from the lowest to the highest weight class, and from inactive to active prey. Most frequently, the owls selected prey of 10 g and 40 g. It was shown that both prey size and activity had an equal influence on the decisions. Predictions were made as to which particular prey size a barn owl was going to choose. With increasing prey weight, the frequency of interrupted prey catching acts and conflict behaviour (mantling, feather ruffling) towards the prey, increased. The upper weight for acceptable active rats was about 80 g. One male, which had to supply his female and nestlings with food, subdued somewhat larger prey. Although relative profitability (net nutritive value/unit of time), calculated from the duration of handling prey, decreased with increasing prey weight, the barn owls chose the larger prey under certain conditions. I discuss a strategy which compromises time and energy costs with the search and subduction of the item.

Costs and Benefits of Brood Care in the Hawaiian Happy Face Spider Theridion grallator (Araneae, Theridiidae)

-The costs and benefits of maternal care in the Hawaiian happy face spider Theridion grallator were studied in the field and laboratory. Adult females were usually found as solitary occupants of the underside of leaves in Hawaiian forests. Individuals generally laid one egg sac, but could lay another if the first was lost. They guarded their egg sacs aggressively, which appeared to be essential for preventing predation, since no egg sac survived in the absence of the mother. Maternal care continued after hatching, with the young feeding communally on prey caught by the mother, being unable to capture prey on their own. This period of posthatching brood care was vital for the reproductive success of the female. Several spiderlings were adopted into the broods of apparently unrelated females. The implications of this phenomenon are discussed.