Food, Feeding Behavior and Feeding Ecology of Nemerteans

The feeding biology of nemerteans is reviewed, new informationis presented, and the role of nemerteans in natural communitiesis discussed and evaluated. Most nemerteans are carnivorous,the majority feeding on live, often specific, prey, while someare scavengers. Macrophagous feeding is found in the Palaeonemertea,Heteronemertea and some of the Hoplonemertea; the more specializedsuctorial feeding is limited to five of the hoplonemertean families,and suspension feeding (omnivorous diet) occurs only in thehighly specialized symbiotic monogeneric Bdellonemertea. Feeding adaptations seem to be related to the nature and employmentof the proboscis, the dilatability of the mouth, and the structureof the anterior part of the digestive tract. The transport ofdissolved organic materials from seawater has been demonstrated,but its role in nemertean nutrition is just being contemplated.Present meager information on predation has shown nemerteansto have actually and potentially large effects on prey populationsand thus on the communities in which they live. As the feedingbiology of only a relative handful of species has been studied,much basic comparative research is needed before we can corroborateor refute our present ideas concerning the ecological rolesof nemerteans.     

饲养条件下织金瘰螈摄食行为的观察

采用室内饲养观察与食物投喂实验相结合的方法,于2011年9月²012年4月研究了织金瘰螈Paramesotriton zhijinensis摄食行为和食物选择。结果表明:织金瘰螈特别喜食的食物包括扁卷螺、萝卜螺、蝌蚪、水丝蚓;较为喜食的食物包括椎实螺、环毛蚓、彩石鲋、蝇蛆、小无齿蚌、河虾、褐栉鰕虎鱼;偶食的食物包括环棱螺、黄粉虫、蜻蜓稚虫、螺类卵带、水生昆虫及幼虫。织金瘰螈发现食物目标靠视觉,判断食物性质靠嗅觉。摄食方式为吞食性摄食。摄食策略主要采取伏击法,并结合搜索法。摄食过程包括:发现食物,靠近并迅速张口咬住食物,食物挣扎时,紧咬不动,食物不动时,借助甩头将食物逐步吞进口腔,进入口腔的食物,通过闭嘴、抬头、头颈后仰、撑起前肢协助进入食道和胃。影响摄食的主要生态因子包括光照、水温和食物密度。     

Primate Crop Feeding Behavior,Crop Protection,and Conservation

Many species across a range of primate genera, irrespective of dietary and locomotory specializations, can and will incorporate agricultural crops in their diets. However, although there is little doubt that rapid, extensive conversion of natural habitats to agricultural areas is significantly impacting primate populations, primate crop foraging behaviors cannot be understood solely in terms of animals shifting to cultivated crops to compensate for reduced wild food availability. To understand fully why, how, and when primates might incorporate crops in their dietary repertoire, we need to examine primate crop foraging behavior in the context of their feeding strategies and nutritional ecology. Here I briefly outline current debates about the use of terms such as human–wildlife conflict and crop raiding and why they are misleading, summarize current knowledge about primate crop foraging behavior, and highlight some key areas for future research to support human–primate coexistence in an increasingly anthropogenic world.     

Humpback Whale Song and Foraging Behavior on an Antarctic Feeding Ground

Reports of humpback whale (Megaptera novaeangliae) song chorusing occurring outside the breeding grounds are becoming more common, but song structure and underwater behavior of individual singers on feeding grounds and migration routes remain unknown. Here, ten humpback whales in the Western Antarctic Peninsula were tagged in May 2010 with non-invasive, suction-cup attached tags to study foraging ecology and acoustic behavior. Background song was identified on all ten records, but additionally, acoustic records of two whales showed intense and continuous singing, with a level of organization and structure approaching that of typical breeding ground song. The songs, produced either by the tagged animals or close associates, shared phrase types and theme structure with one another, and some song bouts lasted close to an hour. Dive behavior of tagged animals during the time of sound production showed song occurring during periods of active diving, sometimes to depths greater than 100 m. One tag record also contained song in the presence of feeding lunges identified from the behavioral sensors, indicating that mating displays occur in areas worthy of foraging. These data show behavioral flexibility as the humpbacks manage competing needs to continue to feed and to prepare for the breeding season during late fall. This may also signify an ability to engage in breeding activities outside of the traditional, warm water breeding ground locations.     

Multi-input Synapses,but Not LTP-Strengthened Synapses,Correlate with Hippocampal Memory Storage in Aged Mice

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人工饲养条件下棕果蝠的摄食行为

2005年8～11月,对北京动物园饲养的棕果蝠(Rousettus leschenaulti)摄食行为进行了研究。每天上午和下午按时喂食,棕果蝠的摄食行为表现出一定的规律性。放置好水果约4min后,1～3只棕果蝠先在食物周围盘旋,然后返回栖息位置;再经约2min开始进食。当果篮中剩余少量水果时,部分棕果蝠到地面取食。上午喂食后,在地面取食的棕果蝠数目出现1个高峰;下午喂食后,地面取食出现4个高峰。下午取食时间显著长于上午(P<0·05)。棕果蝠进食完一块水果后,并不立即再次取食,而是存在一段时间间隔,期间雌雄棕果蝠的行为包括静止、理毛、张望、飞行、抢食、争斗、爬行、排泄、舔生殖区、舔顶棚等。雌雄的行为出现频次存在差异,其中雄性与哺乳期雌性的静止、理毛、飞行、抢食、争斗、舔生殖区行为差异显著(P<0·05);雄性与非哺乳期雌性的静止、理毛、张望、飞行、舔生殖区行为差异显著(P<0·05);哺乳期与非哺乳期雌性的静止、理毛、飞行、抢食行为差异显著(P<0·05)。     

Feeding and Swimming Behavior in Grazing Microzooplankton1,2

ABSTRACT A random-walk model of food-searching behavior is considered for the microzooplankton. It is suggested that in still waters a random walk of the conventional sort, modeled by a Wiener process, is less efficient than a Levy walk (a random walk whose excursions follow a Levy distribution) with Levy parameter less than two. For Levy parameter less than one, however, little advantage is gained by further reduction. In turbulent water, on the other hand, dispersion due to a random walk is dominated by the turbulent diffusion of the medium so that the Levy parameter appears to be less important. The effect of chemosensory responses is considered. It is suggested that these are most useful in still water, whereas in turbulent water their value would be less, and a non-specific filtering behavior might be more plausible.     

Species,Diaspore Volume and Body Mass Matter in Gastropod Seed Feeding Behavior

Background

Seed dispersal of ant-dispersed plants (myrmecochores) is a well studied ecosystem function. Recently, slugs have been found to act as seed dispersers of myrmecochores. The aim of our study was to (1) further generalize the finding that gastropods feed on seeds of myrmecochores and hence may act as seed dispersers, (2) to test whether gastropod body mass and the volume of diaspores have an influence on the seed dispersal potential.

Methodology and Principal Findings

We assessed the seed dispersal potential of four slug and snail species with a set of seven myrmecochorous plant species from seven different plant families common to Central European beech forests. Diaspores differed in shape and size. Gastropods differed in their readiness to feed on diaspores and in the proportion of seeds that were swallowed as a whole, and this readiness generally decreased with increasing diaspore size. Smaller Arionid slugs (58 mm body length; mean) mostly fed on the elaiosome but also swallowed small diaspores and therefore not only act as elaiosome consumers, a nutrient rich appendage on myrmecochorous diaspores, but may also disperse seeds. Large Arionid slugs (>100 mm body length) swallowed diaspores of all sizes. Diaspores swallowed by gastropods were defecated without damage. Within-species variability in body size also affect seed dispersal potential, as larger individuals of the red slug (Arion rufus) swallowed more diaspores of wood anemone (Anemone nemorosa) than smaller ones.

Conclusions and Significance

Our results help to generalize the finding that gastropods consume and potentially disperse seeds of myrmecochores. The dispersal potential of gastropods is strongly influenced by diaspore size in relation to gastropod size.     

Memory Effects on Movement Behavior in Animal Foraging

An individual’s choices are shaped by its experience, a fundamental property of behavior important to understanding complex processes. Learning and memory are observed across many taxa and can drive behaviors, including foraging behavior. To explore the conditions under which memory provides an advantage, we present a continuous-space, continuous-time model of animal movement that incorporates learning and memory. Using simulation models, we evaluate the benefit memory provides across several types of landscapes with variable-quality resources and compare the memory model within a nested hierarchy of simpler models (behavioral switching and random walk). We find that memory almost always leads to improved foraging success, but that this effect is most marked in landscapes containing sparse, contiguous patches of high-value resources that regenerate relatively fast and are located in an otherwise devoid landscape. In these cases, there is a large payoff for finding a resource patch, due to size, value, or locational difficulty. While memory-informed search is difficult to differentiate from other factors using solely movement data, our results suggest that disproportionate spatial use of higher value areas, higher consumption rates, and consumption variability all point to memory influencing the movement direction of animals in certain ecosystems.     

Stimulus Control of Feeding Behavior in the Grasshopper Mouse

This study examined the stimulus control of feeding in the carnivorous grasshopper mouse, Onychomys leucogaster. Quantitative analysis of the actions involved in feeding showed that overall feeding behaviors of lab-reared and field-caught mice resembled one another but that the sequence of specific actions was variable. Responses by mice to cotton swabs dipped in solutions showed that after eating several crickets, the presence of prey odor more readily elicited a feeding response. The odor and moisture cues associated with exposed viscera were shown by the use of modified prey to strongly affect the orientation of feeding. Using modified prey without exposed viscera, tactile cues associated with the head and thorax proved to be important guides in the feeding response. Feeding orientation towards the head was independent of that towards the thorax. Together these data showed that the feeding sequence resembled a reaction chain and that much of the stereotypy of the mouse's feeding response resulted from the position and alignment of the cues that orient the feeding response.     

Glucose, Insulin, and Adrenaline Effects on Some Aspects of Fish Feeding Behavior

Effects of glucose, insulin, and adrenaline on the feeding latent time and the ration in 3 species of fresh-water teleost fish were studied. There has been shown a significant and uniform effect of glucose (an increase of the feeding latent period, a decrease of the ration) and of adrenaline (an increase of the feeding latent period) at initial stages of exotrophia in fish. The insulin effect on the fish feeding reaction rate is not uniform: apart from a statistically significant decrease of the feeding latent period, there were recorded opposite effects.