鳜鱼视觉特性及其对捕食习性适应的研究：Ⅲ.视觉对猎物运动和形状的反应

作者采用行为学方法测定了伏击型凶猛鱼类鳜鱼视觉对猎物运动和形状特征的反应特性。     

鳜鱼视觉特性及其对捕食习性适应的研究Ⅰ．视网膜电图光谱敏感性和适应特性

采用电生理方法研究了夜行性凶猛鱼类鳜鱼视网膜电图的一般特性、光谱敏感性和适应特性。顷鱼的视网膜电图不显示典型的混合型视网膜特征。明视和暗视视网膜电图的光谱敏感曲线形状基本相同,峰值都在５３０ｎｍ处,没有出现Ｐｕｒｋｉｎｊｅ氏位移。明适应曲线仅出现下降型变化,暗适应过程异常缓慢。鳜鱼的视网膜仅存在单一的光感受系统,即暗视系统,不可能形成色觉。但级鱼视网膜具有很高的光敏感性,适于弱光视觉。     

鳜鱼视觉特性及其对捕食习性适应的研究

采用电生理方法研究了夜行性凶猛鱼类鳜鱼视网膜电图的一般特性,光谱敏感性和适应特性。鳜鱼的视网膜电图不显示典型的混合型视网膜特征,明视和暗视视网膜电图的光谱敏感曲线形状基本相同,峰值都在５３０ｎｍ处,没有出现Ｐｕｒｋｉｎｊｅ氏位移,明适应曲线仅出现下降型变化,暗适应过程异常缓慢,鳜鱼的视网膜仅存在单一的光感受系统,即暗视系统,不可能形成色觉,但鳜鱼视网膜具有很高的光敏感性,适于弱光视觉。     

影响尼罗罗非鱼视觉运动反应的因素

本文研究了环境照度、屏幕转速、水温、视野结构和体长等因素对尼罗罗非鱼视觉运动反应的影响,并描述了个体、群体及单眼鱼的反应特点。结果表明：在一定范围内,鱼的视觉运动反应随环境照度和水温的升高而增强,随屏幕转速和体长的增加而减弱。鱼对黑白垂直条纹的反应最好,对倾斜条纹的反应较差,水平条纹则不能引起明显的反应。就垂直条纹而言,在一定范围内,反应随条纹宽度和数量的增加而增强。个体和群体的反应无明显差异。单眼鱼反应明显弱于正常鱼,并有显著的方向性。     

视觉信号在昆虫检测植物寄主中的作用

植物为数十万种昆虫提供各种资源,如食物、交配、产卵和躲避天敌的场所。目前对昆虫检测植物寄主的研究主要关注昆虫嗅觉系统和植物寄主挥发物之间的相互作用,对昆虫视觉系统发挥的作用关注较少。近年来,对昆虫视觉器官、光行为反应及分子生物学的研究表明,昆虫具有优异的视觉能力,能够辨别植物寄主的颜色、大小和轮廓,应该将视觉纳入昆虫检测植物寄主的研究中。昆虫能够利用视觉信号准确检测寄主,远距离时,主要依靠植物寄主轮廓检测寄主,近距离时,寄主的大小、颜色和形状发挥重要作用。利用昆虫视觉识别寄主的专一性研制诱捕装置,可为害虫的监测和防治提供一定的理论基础。     

视觉通道中颜色与形状特征的识别

本文利用计算机设计新的心理物理实验,研究人类视觉系统的颜色、形状通道和对颜色的识别反应,证实视觉系统的颜色通道和形状通道是独立并行的.对颜色反应还进行视觉诱发电位测试,结果与心理物理实验基本一致.最后,提出颜色通道与形状通道间信息相互统一的假说模型.     

不同屏幕角速度下条纹倾角对鲫鱼视觉运动反应特性的影响

视野结构(屏幕图形结构)对鱼类视觉运动反应的影响极为显著,但至今仍缺乏系统的研究。本文较详细地研究了不同屏幕角速度下条纹倾角对鲫鱼(Carassius auratus)视觉运动反应特性的影响,可为探讨鱼类对各种复杂图形运动的反应机制奠定基础,同时在渔业生产中也有一定参考价值。 选用健康鲫鱼作为试验鱼,体长范围 12.2—16.1cm,平均 14.2cm。试验日期为 1989年4月10日—5月 20日。水温范围 12.5—17.4℃,平均 15℃。水中照度范围 650—800lx,平均 725lx。     

拟环纹豹蛛对白背飞虱的嗅觉反应

采用视觉屏蔽法和Y型嗅觉仪法研究了拟环纹豹蛛Pardosa pseudoannulata.雌性成虫对水稻害虫白背飞虱Sogatella furcifera嗅觉反应.在视觉屏蔽的条件下,拟环纹豹蛛对被刺死猎物的捕食成功率为78.95%,高于没有视觉屏蔽蜘蛛的捕食成功率(68.18%),但2者间差异不显著;而在Y型嗅觉仪中,34.38%拟环纹豹蛛雌性成虫能正确选择猎物的方向,显著高于错误的选择(6.25%).因此,拟环纹豹蛛能依靠嗅觉正确判断猎物的方向而进行捕食活动.     

运动结构背景对视觉系统神经元反应的调制作用

对蟾蜍的５６个视顶盖神经元的视觉反应进行了定量考察和分析,发现它们不仅对黑目标起反应,也对结构目标起反应．同相运动的结构背景使５３．５％的神经元的反应完全抑制,而异相运动则只有１０％的神经元完全被抑制,却有２１．６％的神经元反应增强．遮盖感受野（ＲＦ）中心区,则同相运动使某些细胞脱抑制,而异相运动使其抑制强度稍有增强．遮盖ＲＦ的外周区,几乎全部研究过的神经元对结构背景运动本身也起反应。本研究还发现,如果预先将一目标放在兴奋性感受野（ＥＲＦ）中央静止不动,并使结构背景在水平方向匀速移动较长时间后突然停止运动,则被研究过的６６个视盖神经元中有２９个发放一串脉冲,即神经元的运动后放电．各个神经细胞放电的脉冲多寡不一。若在ＥＲＦ中央不放置静止目标,仅是结构背景的水平运动不能诱发放电．此效应的出现,既与目标背景间反差符号（即目标为白色或黑色）无关,也与背景的运动方向无关。为诱发这一效应,不仅要求背景运动时间较长（至少在２０秒以上）,而且目标的面积要有足够大。     

几种幼鱼视觉运动反应研究

对鲻鱼(Mugil cephalus)、鲈鱼(Lateolabrax japonicus)、黄鳍鲷(Sparus latus)、鲤鱼(Cyprinus carpio)和草鱼(Ctenopharyngodon idellus)5种幼鱼进行了视觉运动反应实验。反应率随照度的降低或屏幕转速的提高而下降。高限可跟刺激频率随照度而提高,在10~2lx下,鲻鱼达37次/秒,鲈鱼26次/秒,黄鳍鲷27次/秒,鲤鱼24次/秒,草鱼29次/秒。明暗视过渡照度值:鲻鱼10~0—10~1lx,鲤鱼和草鱼10~(-1)—10~0lx,鲈鱼和黄鳍鲷10~(-2)—10~(-1)lx。照度和刺激频率对反应潜伏期有一定影响。跟随角速度普遍落后于屏幕角速度,即跟随率低于100％,并且随屏幕转速提高而下降。照度对跟随率无明显影响。几种幼鱼对运动条纹的反应可分为三阶段:跟随、活泼运动、无反应。     

Predatory versatility in a larval dragonfly, Hemianax papuensis (Odonata: Aeshnidae)

Larvae of the large dragonfly Hemianax papuensis used four disparate, prey-specific predatory behaviours. Arthropod prey moving on a substratum were stalked and then attacked from a distance. Arthropod prey moving in the water column or at the water surface were approached using 'jet' propulsion and then attacked from a distance. Snails, an unusual prey for an arthropod, were stalked; then the larva manoeuvred about them until a specific orientation was achieved before an attack was made from close range. Dead snails were scavenged, using tactics very similar to those used with live snails, but non-snail carrion was rarely taken. There was no evidence that the possession, by H. papuensis , of specialized behaviours for an atypical prey-snails-lowered its success when attacking other types of 'typical' prey.     

鲜活饵料和人工配合饲料对鳜肌肉营养成分和质构特性的影响

研究以饲喂鲜活饵料为对照组,比较分析人工饲料对鳜(Siniperca chuatsi)常规营养成分、氨基酸组成及营养价值评价、脂肪酸组成和肌肉质构特性的影响。实验结果显示,摄食人工饲料组鳜肌肉蛋白质水平与鲜活饵料组无显著性差异(P>0.05),粗脂肪含量显著较高(P<0.05)。在两种饲喂模式下鳜肌肉中氨基酸评分(AAS)、必需氨基酸指数(EAAI)、化学评分(CS)和F值均无显著差异(P>0.05),但第一限制性氨基酸均为蛋氨酸+半胱氨酸(Met+Cys),该结果可为鳜人工饲料配方优化提供指导。人工饲料组鳜肌肉中饱和脂肪酸(SFA)、单不饱和脂肪酸(MUFA)和多不饱和脂肪酸(PUFA)含量均极显著高(P<0.01),其中C20﹕5(EPA)和C22﹕6(DHA)含量极显著高于鲜活饵料组,表明人工饲料可通过营养素的均衡配比以提供更优质的脂肪酸营养。人工饲料组鳜肌肉硬度、咀嚼性、胶黏性及回复性均极显著高于鲜活饵料组(P<0.01),而黏性极显著低于鲜活饵料组(P<0.01),表明人工饲料饲喂提升了鳜的肌肉质构特性。综上所述,相比于鲜活饵料组,人工饲料...     

The role of sense organs in the feeding behaviour of Chinese perch

Experiments were conducted to identify the roles of the individual sense organs in the feeding behaviour of Chinese perch Siniperca chuatsi by determining the consumption of natural food after selective removal or blocking of eyes, lateral lines and olfactory organs, and also by observing the behavioural response to visual, mechanical and chemical stimulation by artificial prey. Chinese perch were able to feed properly on live prey fish when either eyes or lateral lines were intact or functional, but could scarcely feed without these two senses. Chinese perch recognized its prey by vision through the perception of motion and shape, and showed a greater dependence on vision in predation when both visual and mechanical cues were available. Chemical stimulation by natural food could not elicit any feeding response in Chinese perch, and gustation was only important to the fish for the last stage of food discrimination in the oropharyngeal cavity. The sensory basis of Chinese perch in feeding is well adapted to its nocturnal stalking hunting strategy, and also explains its peculiar food habit of accepting live prey fish only and refusing dead prey fish or artificial diets.     

Prey preference and gregarious attacks by the invasive flatworm Platydemus manokwari

The flatworm Platydemus manokwari (Tricladida: Rhynchodemidae) preys on various species of land snail, and its introduction to areas outside of its native range is thought to have caused the extinction of native land snails on several Pacific islands. Platydemus manokwari occurs in areas where land snails have been absent since its invasion, suggesting that the flatworm can prey on animals other than land snails. To identify the alternative prey and prey preferences of P. manokwari, I examined the feeding ecology of P. manokwari under field and laboratory conditions. Individuals were observed attacking live earthworms in a forest where land snails are already extinct, on Chichijima, Ogasawara (Bonin) Islands, Japan. I also observed them attacking earthworms and a species of isopod and land snail in the lab. To prey on the worm, similar to other earthworm-eating flatworms, P. manokwari wrapped itself around the prey and fed on it by inserting its pharynx into the earthworm’s body. Large earthworms were able to escape P. manokwari attacks by autotomy, but the autotomized body parts were eaten. Several P. manokwari individuals together attacked earthworms that were larger than themselves. The laboratory experiments showed that such gregarious attacks increased predation success on both large earthworms and land snails. The flatworms also attacked the isopods, although the predation rate was low. These results demonstrate that P. manokwari is a polyphagous predator of slow-moving soil invertebrates (land snails, slugs, earthworms, and isopods) and that invasion by P. manokwari may directly and indirectly impact native soil fauna.     

Warning coloration associated with nematocyst-based defences in aeolidiodean nudibranchs

This study examines the mechanisms of aposematism (unprofitabilityof prey combined with a conspicuous signal) in the aeolidioideanCratena peregrina (Gmelin, 1791). We investigated if marinefish avoid attacking aeolidioidean nudibranchs, which are anunprofitable group of prey for most predators. We analysed theinteraction between aeolids and predatory fish in laboratoryand field assays, with both live aeolids and artificial models.In the first experiment, we offered normal and blue-dyed C.peregrina to fish in the field. The number of attacks by fishwas independent of the density of the prey, albeit the normalaeolids were attacked less frequently than the blue ones. Thefact that all normal C. peregrina survived, whereas 12–20%of the blue aeolids died after fish attacks, suggests that aposematiccoloration provides a selective advantage against fish predators.Field and laboratory assays with artificial aeolids were employedto test the effects of different factors (number of cerata,colour pattern, nematocysts), or a combination of factors, onfish learning. Fish learned to avoid unpalatable models withthe colour pattern of C. peregrina. After three to four trainingsessions with unprofitable models, fish avoided profitable modelswith the same colour pattern. Our results suggest that the colourpattern of C. peregrina combined with the presence of dorsalappendages and nematocysts make fish avoid aeolids. (Received 22 January 2004; accepted 18 August 2006)     

Experiments on predation and substratum choice by larvae of the muscid fly, Limnophora riparia

Larvae of the muscid fly Limnophora riparia live in lake outlets and prey on other invertebrates living there. In experiments, we demonstrated that larvae prefer moss as a substratum, though they will bury themselves in any suitable material to avoid light. The substratum is used to anchor Limnophora larvae as they attack their prey. When given a choice of prey they preferred chironomid and black fly larvae to oligochaetes and psyehodid larvae. Larvae of the black fly Simulium noelleri were used in laboratory experiments to test the interaction of predator and prey. Limnophora larvae attacked black fly larvae of all sizes, but preferred small larvae, the body contents of which were often removed completely. Increasing prey or predator density did not affect this latter preference, though an increase in predator density, or a decrease in prey density, did cause the predator to take prey of medium size as well as small prey. Limnophora larvae showed the same size preference when attacking dead (freshly-killed) prey and they preferred to attack larvae rather than pupae when both were available. They did not attack black fly eggs.     

Predation risk cues associated with killed conspecifics affect the behavior and reproduction of prey animals

Organisms often perceive risk to be attacked by natural enemies through cues that accompany or persist after attacks on conspecifics. Under the risk of attack, preys may prioritize anti-enemy behaviours, sacrificing their feeding activities. These enemy-induced changes can affect the prey population growth. The presence of killed congeners is a past attack events cue but, in terrestrial prey–enemy systems, its effect on prey population biology is an open question. This was addressed here by studying both the space use and reproductive effort of aphids exposed to congeners killed by parasitoids. To test whether preys adjust their responses with the threat intensity, aphids' responses in presence of killed conspecifics were compared to those measured when directly exposed to non-consumptive parasitoids. The results showed that killed congeners are perceived by aphids and led to both changes in their space use and a strong decline in their population size. This experiment is the first to demonstrate that the presence of congeners killed by an enemy can contribute to the suppressive effects of natural enemies on prey populations.     

Humpback whales interfering when mammal‐eating killer whales attack other species: Mobbing behavior and interspecific altruism?

Humpback whales (Megaptera novaeangliae) are known to interfere with attacking killer whales (Orcinus orca). To investigate why, we reviewed accounts of 115 interactions between them. Humpbacks initiated the majority of interactions (57% vs. 43%; n = 72), although the killer whales were almost exclusively mammal‐eating forms (MEKWs, 95%) vs. fish‐eaters (5%; n = 108). When MEKWs approached humpbacks (n = 27), they attacked 85% of the time and targeted only calves. When humpbacks approached killer whales (n = 41), 93% were MEKWs, and ≥87% of them were attacking or feeding on prey at the time. When humpbacks interacted with attacking MEKWs, 11% of the prey were humpbacks and 89% comprised 10 other species, including three cetaceans, six pinnipeds, and one teleost fish. Approaching humpbacks often harassed attacking MEKWs (≥55% of 56 interactions), regardless of the prey species, which we argue was mobbing behavior. Humpback mobbing sometimes allowed MEKW prey, including nonhumpbacks, to escape. We suggest that humpbacks initially responded to vocalizations of attacking MEKWs without knowing the prey species targeted. Although reciprocity or kin selection might explain communal defense of conspecific calves, there was no apparent benefit to humpbacks continuing to interfere when other species were being attacked. Interspecific altruism, even if unintentional, could not be ruled out.     

Modulation of prey capture kinematics in the cheeklined wrasse Oxycheilinus digrammus (Teleostei: Labridae)

The ability to modulate prey capture behaviors is of interest to organismal biologists as it suggests that predators can perceive features of the prey and select suitable behaviors from an available repertoire to successfully capture the item. Thus, behavior may be as important a trait as morphology in determining an organism's diet. Using high-speed video, we measured prey capture kinematics in three cheeklined wrasse, Oxycheilinus digrammus. We studied the effects of three experimental prey treatments: live fish, dead prawn suspended in the water column, and dead prawn pieces anchored to the substrate in a clip. Live prey elicited significantly more rapid strikes than dead prey suspended in the water column, and the head of the predator was expanded to significantly larger maxima. These changes in prey capture kinematics suggest the generation of more inertial suction. With greater expansion of the head, more water can be accelerated into the buccal cavity. The attached prey treatment elicited strikes as rapid as those on live prey. We suggest that the kinematics of rapid strikes on attached prey are indicative of attempts to use suction to detach the prey item. More rapid expansion of the buccal or mouth cavity should lead to higher velocities of water entering the mouth and therefore to enhanced suction. Further modulation in response to the attached prey item, such as clipping or wrenching behaviors, was not observed. J. Exp. Zool. 290:88-100, 2001.