Direct benefits of social dominance in juvenile crayfish

Crayfish are known for their innate aggressiveness and willingness to quickly establish dominance relationships among group members. Consequently, the formation of dominance hierarchies and the analysis of behavioral patterns displayed during agonistic encounters have mostly been tested in environments that provide no immediate resources besides space. We tested the hypothesis that social hierarchy formation in crayfish serves to determine access to future resources. Individuals within groups of three juvenile crayfish were allowed to form a social hierarchy in a featureless environment before a single food resource was presented. Higher dominance indices were significantly correlated with increased access to the food. The highest ranked crayfish spent more time in contact with the food than did medium-ranked and lowest ranked crayfish, and crayfish of medium rank spent more time in contact with the resource than did lowest ranked animals. The highest ranked crayfish consolidated their dominant status in the presence of food, indicated by a complete absence of any submissive behaviors during that period. The results of these experiments show that the disposition of crayfish to engage in fighting and formation of a dominance hierarchy in a featureless environment serves to determine future access to an emerging resource, thereby entailing greater benefits for animals of higher social rank.     

Dairy cattle exploratory and social behaviors: is there an effect of cloning?

While an increasing number of animals are produced by means of somatic cloning, behavioral studies on cloned animals are still rare. The aim of this study was to investigate whether the somatic cloning procedure has an influence on locomotion, exploratory, vocal and social behaviors of heifers. Ten heifers were used in the present study. Five of them were cloned heifers derived from somatic cells of three different Prim'Holstein cows and five others were same-age control heifers produced by artificial insemination. In addition to observations of social behaviors in the stable group, each animal was placed individually for a short time in an unfamiliar environment. Our results failed to show any statistical differences between clones and their controls both in frequencies of agonistic and non-agonistic behaviors. However, cloned heifers showed significantly more non-agonistic and less agonistic behaviors towards other cloned partners than towards control ones. This result also stood for control heifers. As far as their Hierarchical Index was concerned, three cloned heifers were highest ranking and two others lowest ranking. In this herd, social dominance appeared to be linked to body weight and age rather than to a cloning effect. In an unfamiliar environment, cloned and control subjects exhibited the same level of locomotion and vocalization. However, cloned heifers showed more exploratory behaviors than did control ones. This difference could be due to environmental factors during the postnatal period rather than to cloning.     

Role of the olfactory pathway in agonistic behavior of crayfish, <Emphasis Type="Italic">Procambarus clarkii</Emphasis>

Crayfish establish social dominance hierarchies through agonistic interactions, and these hierarchies are maintained through assessment of social status. Chemical signals influence several aspects of fighting behavior, but the specific chemosensory sensilla involved in detecting these signals in crayfish are unknown. The goal of our study was to examine the importance of aesthetasc sensilla—olfactory sensors on the antennules of decapod crustaceans—in regulating changes in fighting behavior in crayfish, Procambarus clarkii, over the course of repeated pairings. We selectively ablated aesthetascs from pairs of crayfish after the first day of trials and compared the behavior of these ablated animals to that of pairs of intact controls. Results show that unablated crayfish significantly decreased the number and duration of fights over repeated pairings, whereas crayfish lacking aesthetascs continued to engage in similar amounts of fighting across all three trial days. This difference shows that aesthetascs regulate fighting behavior in P. clarkii.     

Nonconsumptive predator effects modify crayfish‐induced bioturbation as mediated by limb loss: Field and mesocosm experiments

1. We addressed the implications of limb loss and regeneration for multispecies interactions and their impacts on ecosystem engineering in freshwater stream environments.
2. We included regenerative and nonregenerative crayfish as well as fish predators in a 2 × 2 factorial design to assess the effects on water turbidity of interactions between crayfish ecosystem engineers differing in regenerative status and their fish predators.
3. We demonstrated that crayfish limb loss and predation risks lead to more turbidity in field and mesocosm conditions. Moreover, ongoing regeneration of crayfish increased turbidity, while fish presence seemed to hinder crayfish turbidity‐inducing behaviors (such as tail‐flipping and burrowing) in the mesocosm experiment.
4. We confirmed that greater numbers of crayfish produce a greater amount of turbidity in situ in streams.
5. Although mechanical burrowing crayfish capacities may depend on crayfish burrowing classification (primary, secondary, or tertiary), our work emphasizes the implication for turbidity levels of crayfish autotomy in freshwater streams.

     

Serotonin and octopamine elicit stereotypical agonistic behaviors in the squat lobster Munida quadrispina (Anomura, Galatheidae)

Serotonin and octopamine have been implicated as modulators of posture and behavior in several crustaceans. Here we characterize the agonistic behaviors of normally interacting squat lobsters Munida quadrispina (Anomura, Galatheidae) and their responses to serotonin and octopamine injected into the ventral hemolymph sinus, in order to evaluate the potential roles of these amines in modulating agonistic behaviors. Normally interacting M. quadrispina do not develop lasting dominance hierarchies, although transient aggressive and submissive displays do occur. Injected serotonin elicits postures and behaviors in isolated individuals similar to those typical of aggressive, normally interacting animals. Injected octopamine can produce postures and behaviors typical of submissive animals, and elicits behaviors which imply a modulatory role for octopamine in tailflipping. The effects of both amines are reversible and dose dependent, and the dose-response curves parallel the normal progression of agonistic interactions. The social behaviors and reactions to injected serotonin and octopamine of M. quadrispina differ from those of lobsters and crayfish, indicating that interspecific differences in neuromodulation of behavior and motor output exist. Such differences have implications for the understanding of aminergic modulation of aggression and the evolution of aminergic modulation in crustaceans. Accepted: 22 June 1997     

Importance of cooperation and affiliation in the evolution of primate sociality

The idea that competition and aggression are central to an understanding of the origins of group‐living and sociality among human and nonhuman primates is the dominant theory in primatology today. Using this paradigm, researchers have focused their attention on competitive and aggressive behaviors, and have tended to overlook the importance of cooperative and affiliative behaviors. However, cooperative and affiliative behaviors are considerably more common than agonistic behaviors in all primate species. The current paradigm often fails to explain the context, function, and social tactics underlying affiliative and agonistic behavior. Here, we present data on a basic question of primate sociality: how much time do diurnal, group‐living primates spend in social behavior, and how much of this time is affiliative and agonistic? These data are derived from a survey of 81 studies, including 28 genera and 60 species. We find that group‐living prosimians, New World monkeys, Old World monkeys, and apes usually devote less than 10% of their activity budget to active social interactions. Further, rates of agonistic behaviors are extremely low, normally less than 1% of the activity budget. If the cost to the actors of affiliative behavior is low even if the rewards are low or extremely variable, we should expect affiliation and cooperation to be frequent. This is especially true under conditions in which individuals benefit from the collective environment of living in stable social groups. Am J Phys Anthropol 128:84–97, 2005. © 2005 Wiley‐Liss, Inc.     

The smell of success and failure: the role of intrinsic and extrinsic chemical signals on the social behavior of crayfish

Animals commonly modify their behavior in the presence of aconspecific or in response to signals. This is particularlytrue in the context of aggressive exchanges, which animals useto form networks of social relationships and to communicatesocial status associated with those relationships. Althoughhierarchical structures are a widespread phenomenon that hasbeen studied extensively, the dynamic communication processes,specifically chemical communication in this review, is relativelyoverlooked. In particular, it is the exchange of informationduring agonistic interactions that mediates hierarchies and/oralters the outcomes of agonistic interactions. Given the theoreticalappeal of these interactions, and the evolutionary importanceand taxonomic diversity associated with social hierarchies,it is not surprising that the sensory mechanisms involved inthe formation and maintenance of hierarchical structures havereceived recent attention. In crayfish, dominance is thoughtto be largely determined by physical superiority, where encountersare largely dyadic and fighting behavior is highly stereotyped.However, recent evidence has shown that the outcome of dyadicencounters are dependent upon a number of factors other thanphysical size, that include the exchange of chemical informationduring encounters, previous social history, and the intrinsicneurochemical state of opponents. We have attempted to providea comprehensive analysis of the extrinsic chemical processes(previous history, sensory communication, etc.) and intrinsicchemical processes (neurochemical state) that produce and maintaindominance relations and social hierarchies in crayfish. We hopethat this review will bring together a global picture of theprocesses that determine a crayfish's social standing and howintrinsic and extrinsic chemicals have substantial effects onaggressive states and agonistic bouts.     

The influence of social experience on the behavior of male cockroaches,Nauphoeta cinerea

The influence of social experience on rates of agonistic behavior was investigated in a cockroach, Nauphoeta cinerea. Social experience was manipulated by establishing three types of groups of four identically aged males: (1) ran-domly chosen, socially naive males (control); (2) males of similar status and activity level (from treatment 1); and (3) males returned to their original hierarchy after experiencing treatment 2. In the control groups, we found stable hierarchies, significant differences in the rate of agonistic behaviors exhibited among different status males, and a significant relationship between social status and level of agonism. We also compare activity levels within and among groups after males had novel social experiences. Among similar status individuals, we found less activity than when they wereintheir original groups. When males were returned to their original groups, the level of activity increased compared to the level of activity before treatment. The social status of males was unstable after these treatments. Losing tended to result in relatively more subordinate behavior, and winning in relatively more dominant behavior by a male. Within groups, the rate of agonism also increased over 5 days in groups of males that had no previous interactions with each other, while the rate of agonism remained the same in groups of familiar males. We interpret these results in light of male-male assessment and the maintenance of social status in this species.     

Social cues and hormone levels in male Octodon degus (Rodentia): a field test of the Challenge Hypothesis

Social interactions are important factors determining and regulating individual behaviors. Testosterone has been related to agonistic interactions, while glucocorticoids have been related to social stress, especially during interactions of dominance. We compared testosterone and cortisol concentrations in male degus (Octodon degus, Rodentia) under laboratory conditions without male social interactions, with data from wild males in nature. Under natural conditions, males should present higher levels of testosterone during the breeding season due to social interactions (Challenge Hypothesis). Alternatively, intense social instability could act as a stressing environment, raising glucocorticoids, which inhibit testosterone concentrations. Our results show a significant increase in agonistic interactions between males during the breeding season, and disappearance of non-agonistic male interactions during this period. Hormone levels in breeding season show nonsignificant differences between laboratory groups, but testosterone concentrations in field males were significantly higher than in laboratory males. Testosterone levels were similar among pre-breeding and breeding periods, but in field animals the concentration was approximately 30% higher than in laboratory degus. In field animals, we found two different mating strategies: resident males, with territorial behavior, and transient males, displayed an opportunistic approach to females. Finally, cortisol presents a similar pattern in both laboratory and field animals; pre-breeding values of cortisol are higher than during the breeding season. This suggests that social interactions in O. degus activate a rise in testosterone, supporting the Challenge Hypothesis, and could be considered as partial support of the Social Stress Hypothesis.     

Heart and ventilatory measures in crayfish during environmental disturbances and social interactions

Most animals assess the environment in which they live and alter their behavior according to various stimuli. When the animal does not make significant behavioral changes, as measured by bodily movements, the animal may be characterized as unresponsive to a given stimulus. This study demonstrates that when behavioral movements of crayfish cannot be observed, physiological measures of heart rate (HR) and ventilatory rate (VR) show dramatic changes in response to defined sensory stimuli. In the majority of cases, upon anticipation of a social interaction with another crayfish both HR and VR will increase. During an agonistic encounter between two crayfish, the level of HR and VR correlate with the intensity of the interaction. Such rapid responses in cardiac and respiratory systems to environmental disturbances and anticipation of a social interaction suggest an autonomic-like regulation associated with fear, flight or fight. Since behavioral observations do not allow an internal status to be readily assessed, we suggest that HR and VR may serve as a useful bioindex in crustaceans to their internal drive or possibly an awareness level to environmental cues.     

不同地位克氏原螯虾对社会环境改变的行为反应

为探究不同社会地位的亚成体克氏原螯虾(Procambarus clarkii)对利益的分配,以及对社会环境改变(体型较大的入侵同类)各自做出的行为反应,本文统计已确立等级序列的成对同性别螯虾对隐蔽所的占有情况,并视频拍摄同性别螯虾入侵时,入侵者及不同地位的原居者的格斗行为,分析格斗次数、格斗时间、首次攻击及被首次攻击对象多个参数。在隐蔽所占有实验中,71%为优势者占有隐蔽所,7%为从属者占有,共同占有或没有占有的各11%。在入侵-反入侵实验中,雄性入侵者对2只原居虾之间的攻击选择无显著差异,雌性入侵者首次攻击显著选择与原优势者格斗;雄性原居者中优势者对入侵者和原从属者的攻击无显著差异,雌性优势者则显著选择与入侵者格斗;雄性原居者中从属者显著选择与入侵者格斗,雌性从属者对入侵者和原优势者的攻击无显著差异。上述结果表明,优势者优先占有资源;雌雄螯虾在入侵和面临入侵时有各自不同的策略;不同地位的螯虾在反入侵时行为反应也各有不同。     

Male–Female Communication in the Crayfish Orconectes rusticus: The Use of Urinary Signals in Reproductive and Non-Reproductive Pairings

Animals use sensory communication to locate conspecifics, food, shelter, and avoid predators. Using urine visualization techniques as well as Digital Particle Illumination Velocimetry, we examined the role of urinary signals and current generations during social interactions of male and female crayfish. Both reproductive and non‐reproductive crayfish were paired to gain a better understanding of how reproductive state influences communication. Analyses of agonistic and mating events were paired in time with recorded urine release and current generation, illustrating a correlation of chemical communication with ritualized social behavior. Four treatment groups were run with specific combinations of different reproductive status: (1) both opponents reproductively active, (2) only the male in reproductive, (3) only the female reproductive, or (4) both opponents non‐reproductive. Results showed differences between treatment groups in urine release, current generation, and social behavior. Within reproductive pairings, both the male and female crayfish generated currents and released urine at higher rates than those in other treatment groups. Urine was released most often when opponents were in chelae contact with each other and these releases were often accompanied by anterior current generation. In addition, communication was different in reproductive trials where mating occurred. Overall, the results indicate that the use of hydrodynamic and chemical signals changes as a function of reproductive state and that this change in communication probably indicates readiness to mate.     

Effects of serotonin and serotonin analogs on posture and agonistic behavior in crayfish

Exogenous serotonin has been shown to induce an elevated, flexed posture in crustaceans and has also been hypothesized to enhance aggressive behavior. We conducted three experiments to further investigate the effects of serotonin and serotonin analogs on posture and agonistic behavior in the crayfish Procambarus clarkii. In the first experiment, we recorded behavioral responses to five different concentrations of serotonin injected into the ventral hemolymph sinus. The amine elicited a series of behaviors including the characteristic high, flexed posture, but none were clearly associated with aggression. In our second experiment, we tested serotonin and four serotonin receptor agonists [1-(3-chlorophenyl)piperazine dihydrochloride, 2-methyl-5-hydroxytryptamine maleate, 5-carboxamidotryptamine maleate and alpha-methyl-5-hydroxytryptamine maleate] and measured the ability of each agonist to mimic the actions of the amine. High concentrations of 1-(3-chlorophenyl)piperazine dihydrochloride most closely mimicked the actions of serotonin; 5-carboxamidotryptamine maleate induced a high stance, but did not otherwise induce effects similar to serotonin. In our third experiment, we conducted an analysis of fighting behavior between pairs of crayfish that had received injections of control saline, serotonin, or 5-carboxamidotryptamine maleate. Serotonin generally reduced the level of aggression between opponents, whereas 5-carboxamidotryptamine maleate enhanced the performance of several agonistic behaviors.     

Group housing during gestation affects the behaviour of sows and the physiological indices of offspring at weaning

To compare the behaviour of sows and the physiological indices of their offspring in stall and group-housing systems, 28 sows were randomly distributed into two systems with 16 sows in stalls, and the other 12 sows were divided into three groups with four sows per pen. The area per sow in stalls and groups was 1.2 and 2.5 m², respectively. Back fat depth of the sow was measured. Salivary cortisol concentration of the sows, colostrum composition and piglets’ serum biochemical indicators were evaluated. The behaviour of the sows, including agonistic behaviour, non-agonistic social behaviour, stereotypical behaviour and other behaviours at weeks 2, 9 and 14 of pregnancy were analysed. The results showed no differences in the back fat depth of sows. Colostrum protein, triglyceride, triiodothyronine, thyroxine and prolactin concentrations in the whey also demonstrated no significant differences between the two housing systems. Salivary cortisol concentration was significantly higher in the sows housed in groups than the sows in stalls. The concentrations of serum total cholesterol and low-density lipoprotein (LDL) cholesterol were significantly higher in the offspring of sows housed in groups (P=0.006 and 0.005, respectively). The GLM procedure for repeated measures analysis showed the frequency of drinking, and non-agonistic social behaviour was significantly higher in the sows housed in groups than the sows in stalls; yet the frequency of agonistic and sham chewing demonstrated the opposite direction. The duration of standing was significantly longer in the sows housed in groups, but the sitting and stereotypical behaviour duration were significantly shorter compared with the sows in stalls. These results indicated that group housing has no obvious influence on the colostrum composition of sows; however, it was better for sows to express their non-agonistic social behaviour and reduce the frequency of agonistic behaviour and stereotypical behaviour. Meanwhile, group housing during gestation significantly increased serum total cholesterol and LDL cholesterol of offspring.     

Ritualized submission and the reduction of aggression in an invertebrate

Ritualized behaviors that signify acceptance of a dominance relationship and reduce aggression between rivals are a common feature of vertebrate social behavior. Although some invertebrates, including crayfish, lobsters, and ants, display dominance postures, more complex dominance rituals and their effects on fitness have not been reported. We found that crayfish display such a complex ritual, when two males engaged in pseudocopulatory behavior to signify their dominance relationship. This was followed by a reduction in aggression and an increased likelihood of the subordinate's survival. Pseudocopulation was initiated by the eventual dominant and could be accepted or refused by the eventual subordinate. The frequency of aggressive behavior declined significantly during the first hour in all pairs that pseudocopulated but remained high in pairs that did not. Whereas all the subordinate members of pairs that pseudocopulated survived the initial 24 hr of pairing, half of subordinates that did not pseudocopulate were killed during that time. This differential mortality indicates that the reduction of aggression induced by the pseudocopulatory ritual directly enhances the differential survival of male crayfish that engage in this behavior.     

Agonistic behavior in crayfish in relation to temperature and reproductive period

Summary I examined the relationship between temperature and agonistic behavior in the crayfish Cambarus latimanus LeConte a species which is reproductively active in winter. Crayfish were acclimated for 2 wks at 9.5, 14, 22 and 30°C in summer and at 9.5 and 22°C in winter. Agonistic behavior of pairs of the same sex was recorded for 1 h following acclimation. The entire acclimation, testing, and temperature-readjustment procedure was repeated until all crayfish pairs had been tested at each acclimation temperature.Published information on lobsters and catfish indicate that agonistic behavior is directly related to temperature. In contrast, for C. latimanus in the present study, duration of total agonistic behavior, maximum duration of a single agonistic interaction, and average length of a agonistic encounter were all inversely related to acclimation temperature. I hypothesized that for ectothermic species whose agonistic behavior is closely associated with reproductive processes (including competition for mates) the level of agonism will vary either directly or inversely depending upon whether the reproductive period is cued by increasing or decreasing seasonal temperatures, respectively.     

Future social rank: forecasting status in the green anole (Anolis carolinensis)

Predicting the future social standing of an individual without aggressive social interaction may seem contradictory, as formation of social rank depends on agonistic interactions. In the lizard Anolis carolinensis, predicting social rank is possible using latency to eyespot formation (sympathetic darkening of postorbital skin from green to black during stressful agonistic interactions), because they form more rapidly in male lizards that become dominant. Darkened eyespots also inhibit aggressive behavior. As the timing of eyespot formation appears to be an important component of stress responsiveness and future social status, we hypothesized that a proactive disposition toward non-aggressive behavior, such as feeding and courtship, would be associated with aggressiveness. We assessed the relationship between rank and the temporal dynamics of eyespot formation, latencies to aggressive display, feeding, and reproductive behavior. Male lizards that became dominant were faster to respond to all types of stimuli tested (aggression, feeding, and courtship). The temporal dynamics of the neuroendocrine stress response appear to influence the motivation for behavioral response. Animals that recover from stress more quickly also eat, court, and fight more readily. In summary, this work suggests that latencies to aggressive, reproductive, and feeding behavior, as well as eyespot signals, are reliable predictors of future social status of individual male A. carolinensis.     

A comparison of crayfish burrow morphologies: Triassic and Holocene fossil,paleo‐ and neo‐ichnological evidence,and the identification of their burrowing signatures

The architectural and surficial morphologies of crayfish burrows from the Upper Triassic Chinle Formation and Holocene sediments were compared in order to determine: 1) if Triassic burrows could truly be attributed to crayfish activity; 2) how comparable the burrowing mechanisms are; and 3) whether or not a common set of burrowing signatures could be identified for both ancient and modern freshwater crayfish. Materials used in this study include burrows from the members of the Upper Triassic Chinle Formation, casts of modern burrows constructed by Procambarus clarkii Hobbs and Procambarus acutus acutus (Girard) in the laboratory, and casts of naturally constructed modern burrows of Cambarus diogenes di‐ogenes (Girard).

Triassic and Holocene crayfish burrow morphologies exhibit simple to complex architectures, varying degrees of branching, chamber, and chimney development. They also exhibit relatively textured surficial morphologies (bioglyphs) such as scrape and scratch marks, mud‐ and lag‐liners, knobby and hummocky surfaces, pleopod striae, and body impressions. Holocene crayfish construct distinctive burrows due to their conservative limb arrangement, functional morphology, and behavior with respect to environmental stimuli. Similarities between Holocene and Triassic crayfish burrows suggest that extant and Triassic crayfish employed identical burrowing mechanisms. Features of the surficial and architectural morphologies impart a distinctive signature to burrows of both ancient and modern freshwater burrowing crayfish.

Burrowing signatures of crayfish can be used to identify new and previously misinterpreted continental trace fossils. These are useful in studies of the paleohydrogeology, paleoclimatology and paleoecol‐ogy of burrow‐bearing deposits.     

Competition for limited environmental resources on the social dominance model in laboratory mice

Asymmetry of social rank in the competition for food and female was studied using the social dominance model with only two male mice. Marking activity was recorded as a useful indicator of the social status. Social rank was determined by asymmetry in aggressive behavior. A food test was presented for 10 min daily within 5 days of the experiment, whereas a sexual test was performed only on the 5th day for 30 min. Marking behavior was estimated twice: before the first interaction and on the 4th day of the experiment. The competition for food was accompanied by active attacks, escapes, vertical defense postures, and sniffing. The level of aggression, sniffing, and food activity was higher in dominant than submissive males. Time course of aggressive, defensive, and sniffing behaviors was characterized by maximum scores in the period of formation of social hierarchy; however, the rate of food activity in this period was low and increased only to the 4th day. Introduction of a receptive female into the male group with the stable social hierarchy stimulated the intermale aggression, defensive and sniffing behaviors. Dominant males were characterized by a greater number of victories over and sniffing contacts with both male and female. Marking activity was also more intense in dominants. Thus, significant unidirectional rank differences in agonistic, sniffing, food, sexual, and marking behaviors were shown on the social dominance model with the minimum number of partners.     

长江河口湿地不同植被中无齿螳臂相手蟹的分布及其洞穴利用

无齿螳臂相手蟹(Chiromantes dehaani)是长江河口中、高潮滩的优势底栖动物之一,具有重要的生态功能.由于其经济价值较低,所受关注很少.本文调查了相似高程芦苇(Phragmites australis)带、芦苇斑块、菰(Zizania aquatica)植被以及裸地4种生境中无齿螳臂相手蟹的数量分布及其洞穴的利用情况.有植被分布的3种生境间植株密度、植株高度和植物干重生物量(地上部分)差异显著(P＜0.001);4种生境问,陷阱桶采样获取的无齿螳臂相手蟹数量分布(P＜0.001)和性比(P=0.001)差异显著;裸地区域没有无齿螳臂相手蟹可用的洞穴分布,芦苇带、芦苇斑块和菰植被间无齿螳臂相手蟹可用的洞穴密度(P＜0.019)、单位洞穴蟹个体数(P＜0.001)差异显著,挖掘洞穴采样获取的无齿螳臂相手蟹密度差异接近显著水平(P=0.067),洞穴占用率(P=0.667)、不同洞穴占用方式频次组成(P＞0.05)差异不显著;无齿螳臂相手蟹可利用洞穴密度与植株密度、植物干重生物量显著负相关(P＜0.05),而挖掘洞穴采样获取的无齿螳臂相手蟹密度与植株高度(P=0.077)相关性接近显著水平且与洞穴密度(P＜0.001)显著正相关.这些结果表明盐沼植被对无齿螳臂相手蟹的分布和洞穴利用存在影响.而进一步探讨盐沼不同植被对无齿螳臂相手蟹分布的影响,需要先了解无齿螳臂相手蟹在不同植被中分布格局在时间上的变化,并结合无齿螳臂相手蟹在不同植被间的迁移行为以及繁殖周期等进行探讨.