Pelagic swarms and beach strandings of the squat lobster Munida gregaria (Anomura: Munididae) in the Beagle Channel, Tierra del Fuego

The present article is the first formal record of pelagic swarms and beach strandings of the squat lobster Munida gregaria in the Beagle Channel, southern South America. To describe size composition and natural diet of beach strandings and swarms, samples from strandings were taken in April 2007, March 2008 and March 2010. Samples from swarms were taken in May 2007 and April 2010. Also, during November 2008 and January 2009, two acoustic surveys were carried out to describe both, horizontal distribution and school metrics of swarms. Pelagic swarms and beach strandings were composed of 100% individuals of the morph gregaria of M. gregaria. Mean size of males and females in both, beach strandings and swarms, were similar. The diet of pelagic M. gregaria was composed mainly of crustaceans, unicellular algae and small macroalgae, sediment and particulate organic matter. Swarms of pelagic Munida took the shape of extended layers of varying density and height. Their positions in the water column were also variable: swarms were found at different depths, from the subsurface layer to near the sea bottom. Occasionally, some large swarms occupied most of the water column. In the Beagle Channel, SW winds during spring tides could be a forcing factor for M. gregaria strandings. The absence of shoaling animals in the Beagle Channel between 1997 and 2002 and the recent occurrence of swarms are coincident with their appearance in other locations in Patagonia. In consequence, we hypothesize that the factor influencing the formation of swarms must be acting at a regional scale.     

Larval development of the subantarctic squat lobster Munida subrugosa (White, 1847) (Anomura: Galatheidae), reared in the laboratory

The larval development of the squat lobster Munida subrugosa from subantarctic waters of the Beagle Channel (Tierra del Fuego, Argentina) was studied under controlled laboratory conditions of temperature, salinity, and food supply. Developmental times, survival, and growth of larvae and early juveniles were investigated. Hatching of the entire brood always occurred during one night. Larvae were kept in 100ml individual bowls with filtered seawater at 8 ± 0.5°C and fed with Artemia spp. nauplii three times a week. Larvae passed through 6 zoeal instars and one megalopa. Previously, only five zoeal instars were known from this species. Mean cumulative durations of the zoeal stages I to VI were: 20.5 ± 2.5, 33.9 ± 4.1, 43.3 ± 5.4, 52.6 ± 5, 61.2 ± 3.9, and 83days, respectively. By adding the 28days that a single megalopa took to metamorphose to crab I stage, the complete larval development lasted 111days. Highest mortality occurred prior to the moult from the zoea I to zoea II stage (79.21% ± 18.65%) and during the moult from zoea VI to megalopa (92.86%). Carapace length was 1.64 ± 0.06, 1.52 ± 0.16, 1.57 ± 0.26, 1.64 ± 0.21, 2.11 ± 0.35, and 2.58 ± 0.19mm, for zoeal stages I to VI, respectively. Carapace length of megalopae and crab I instars was similar (2.85 ± 0.28 and the 2.84 ± 0.05, respectively). Unlike other subantarctic decapods, which show a tendency towards abbreviated larval development and/or some degree of endotrophy, M. subrugosa shows an extended planktotrophic larval development synchronized with short seasonal plankton production in austral summers.     

Light modulation of postural flexor motoneurones in the tail-fan of the squat lobsterGalathea strigosa (Crustacea,Anomura)

Summary Photosensitivity in the terminal abdominal ganglion (G5) of an anomuran, the squat lobsterGalathea strigosa (Crustacea, Decapoda, Anomura), is described. In contrast to the caudal photoreceptors (CPRs) of long-tailed natantid and macruran decapod crustaceans, the caudal photosensitive elements in G5 inG. strigosa apparently lack the conventional spiking rostral conduction pathways to the thoracic ganglia, and instead make their output connections to a bilateral pair of tonic flexor motoneurones originating within the caudal ganglion itself. These flexor motoneurones modulate the activity of two bilaterally paired uropod coxopodite tonic flexor muscles. This photomodulated motoneurone (PMMN) activity is not abolished by sectioning the abdominal nerve cord anterior to G5. The pattern of photosensitivity, while differing from that shown by other CPRs, resembles instead the pattern attributed to photosensitive interneurones (PSIs) of rostral abdominal ganglia of crayfish and other long-tailed decapod crustaceans.The caudal PSIs inG. strigosa appear to be involved in the postural control of the tail-fan as it is held flexed against the cephalothorax.     

Taxonomic status of two South American sympatric squat lobsters, Munida gregaria and Munida subrugosa (Crustacea: Decapoda: Galatheidae), challenged by DNA sequence information

We investigated the taxonomic status of two sympatric morphospecies of squat lobsters from southern South America (Beagle Channel, Strait of Magellan, and Burdwood Bank), Munida gregaria and Munida subrugosa , by DNA sequence analysis of three mitochondrial (mt)DNA gene fragments [416 bp of 16S rDNA(165), 566 bp of cytochrome c oxidase subunit I(COI) and 418 bp of NADH dehydrogenase subunit 1 (ND1)]; and the nuclear rDNA internal transcribed spacer (ITS) 1 (883–952 bp). We obtained a total of 79 sequences from 32 individuals. The 16S sequences of all M. gregaria and M. subrugosa were invariant and identical, whereas COI and ND1 showed 12 and 15 variable sites, respectively. These polymorphisms were shared between morphospecies. Interspecific Tamura–Nei distances for COI and ND1 sequences were 0.0024 and 0.0032, respectively, and were not significantly different from intraspecific distances (Kruskal–Wallis tests: P  = 0.58 and P  = 0.69, for COI and ND1, respectively). Similar to the results obtained from the mtDNA sequences, no relationship was found between the ITS1 maximum parsimony tree topology and the morphologic classification of specimens in M. gregaria and M. subrugosa . We conclude that M. gregaria and M. subrugosa from southern South America may either represent a case of a dimorphic species, or a case of incomplete lineage sorting. The fact that these two morphospecies did not show fixed differences over a total of 1947 bp analysed reinforces the hypothesis of a single dimorphic species.  © 2008 The Linnean Society of London, Biological Journal of the Linnean Society , 2008, 94 , 421–434.     

Absence of a prezygotic behavioural barrier to gene flow between the two sympatric morphs of the squat lobster <Emphasis Type="Italic">Munida gregaria</Emphasis> (Fabricius, 1793) (Decapoda: Anomura: Galatheidae)

Munida gregaria and M. subrugosa have been considered two different species for more than a century; however, after a recent molecular phylogenetic study, they are considered a single polymorphic species. Yet, the use of markers to diagnose species may be misleading when divergence between species is recent, since a speciation event may be obscured by the retention and stochastic sorting of ancestral polymorphisms. The morphs gregaria and subrugosa of Munida gregaria constitute an interesting case for the study of behavioural isolation since they are sympatric, breed at the same time of the year, and might have experienced a recent speciation. Mating behaviour observations and mate choice mating trials were conducted in order to investigate the potential existence of a behavioural prezygotic barrier to gene flow between these two morphs. Since factors involved in mate choice in galatheids are unknown, the four possible combinations of the two different morphs in trios were used to test for the existence of mate choice. Video recordings of all the possible trio combinations revealed that there was cross-attraction between males and females of different morphs. Females bearing partial broods participated in encounters as well as non-ovigerous females. The frequency and duration of homo- and heterotypic encounters were registered, and a reproductive isolation index was calculated for each variable for each trio. The isolation indexes calculated were not different from zero indicating random mating, and were not affected by the composition of the trio or the partial ovigerous condition of females. These results provided evidence of the absence of behavioural prezygotic barriers to gene flow between the morphs gregaria and subrugosa of M. gregaria.     

Behavioral effects of serotonin and serotonin agonists in two crayfish species, Procambarus clarkii and Orconectes rusticus

Exogenous serotonin elicits several behaviors in Procambarus clarkii, including a flexed, elevated posture, reduced locomotion, and changes in aggressive behavior. We conducted experiments to determine if several serotonin agonists mimicked the behavioral effects of serotonin in two crayfish species, P. clarkii and Orconectes rusticus. Drugs tested were 1-(3-Chlorophenyl)-piperazine dihydrochloride (mCPP), Oxymetazoline, 2,5-dimethoxy-4-iodoamphetamine (DOI), CGS-12066A, and (+/-)-8-hydroxy-2-(di-n-dipropylamino) tetralin (8-OH-DPAT). In P. clarkii, mCPP most closely mimicked the effects of serotonin, significantly increasing the performance of the flexed, elevated posture and reducing locomotion; 8-OH-DPAT significantly reduced locomotion as well. Both of these drugs produced significant increases in elevated posture and decreases in locomotion in O. rusticus, and in this species, the drugs at test concentrations were more effective in eliciting these effects than serotonin. The effects of the drugs on behaviors performed during fighting bouts were variable. In both species, only 8-OH-DPAT significantly reduced several agonistic behaviors, and no agonist or 5-HT itself produced significant increases in agonistic behavior.     

Combined effects of octopamine and filling pressure on the isolated heart of the lobster,Panulirus japonicus

Summary The effects of octopamine (OA) on the isolated and pumping heart of Panulirus japonicus were investigated. Under low filling pressure, OA (10^-7-10^-5 M) decreased the heart rate and enhanced the first systolic contraction (FSC) while reducing the second systolic contraction (SSC). The decrease in heart rate was transient whereas the enhancement of the FSC continued for 10 min or more after washout of OA. Pressure and OA synergistically intensified the FSC and reduced the SSC. The effect of OA on heart rate changed from a deceleration to an acceleration as the pressure was raised. Octopamine decreased both the firing frequency and the burst rate of the small cardiac neurons in a dose-dependent manner. In contrast, the amine often induced a slow ramp potential in the large cardiac neurons and increased their burst rate. Octopamine had no effect on the excitatory junction potentials evoked in cardiac muscle cells. Contraction and closure of the posterior cardioarterial valve were induced by OA, resulting in rebound internal heart pressure and stretching of the heart. The stretch augmented the heart rate and the FSC. The inhibition of small cardiac neurons by OA was related to the reduction of the heart rate and the SSC. The activation of large cardiac neurons and of cardiac and valve muscles by OA augmented the heart rate and the FSC. These multiple actions on the perfused heart lead to abolition of the SSC. After abolition of the SSC, increases of pressure can rapidly raise the heart rate.Abbreviations EJP excitatory junction potential - FLP first large potential - FSC first systolic contraction - OA octopamine - SLP second large potential - SSC second systolic contraction     

Effects of physical and social experiences and octopamine receptor agonist on fighting behavior of male crickets Velarifictorus aspersus (Orthoptera: Gryllidae)

Fighting commonly occurs among animals and is very important for resolving conflicts between conspecific individuals over limited resources. The plasticity of fighting strategies and neurobiological mechanisms underlying fighting behavior of insects are not fully understood. In the present study, we examined whether physical and social experiences affected the aggressiveness of males of the cricket Velarifictorus aspersus Walker, and whether an octopamine (OA) receptor agonist could affected the aggressiveness of males exposed to different experiences. We found that flight and winning a fight significantly enhanced male aggressiveness, while losing a fight significantly suppressed male aggressiveness, consistent with the findings of existing studies on other cricket species. We also found that female presence had a stronger enhancing effect on male aggressiveness than flight or winning a fight. These findings demonstrated that physical and social experiences can affect the fighting behavior of male V. aspersus. Topical application of a 0.15?M solution of an OA receptor agonist (chlordimeform, CDM) significantly increased male aggression level, suggesting that OA may play an important role as a neuromodulator in controlling fighting behavior of males of this species. Despite displaying a significantly higher aggression level (level 5 or 6), CDM-treated losers did not escalate to physical combat, while fights between courting males usually resulted in physical escalation. It is likely that fighting behavior is only partly regulated by OA, and additional regulatory pathways may be involved in achieving physical combat.     

雄性大仓鼠体重对其斗殴行为及社会等级的作用

在实验室条件下测定雄性大仓鼠体重对社会等级和斗殴行为的作用模式,检验体重对雄性大仓鼠社会等级及斗殴行为序列具有重要影响的假设。本实验以16只成年雄性大仓鼠为目标个体,采用等级内部的线性概率、组内循环三元组数量（d）和优势等级的线性度（K）,排列个体的社会等级序位。研究结果表明,雄性大仓鼠可形成近似线性的优势等级,体重与个体的优势等级,攻击行为和胁腺标记行为均呈显著的正相关关系,与防御行为和攻击潜伏期存在显著的负相关关系。说明独居性物种大仓鼠雄体间可形成优势等级关系,体重对此关系具有重要的作用。     

Morphological and molecular description of new species of squat lobster (Crustacea: Decapoda: Galatheidae) from the Solomon and Fiji Islands (South‐West Pacific)

The family Galatheidae is among the most diverse families of anomuran decapod crustaceans, and the South‐West Pacific is a biodiversity hot spot for these squat lobsters. Attempts to clarify the taxonomic and evolutionary relationships of the Galatheidae on the basis of morphological and molecular data have revealed the existence of several cryptic species, differentiated only by subtle morphological characters. Despite these efforts, however, relationships among genera are poorly understood, and the family is in need of a detailed systematic review. In this study, we assess material collected in different surveys conducted in the Solomon Islands, as well as comparative material from the Fiji Islands, by examining both the morphology of the specimens and two mitochondrial markers (cytochrome oxidase subunit I, COI, and 16S rRNA). These two sources of data revealed the existence of eight new species of squat lobster, four of which were ascribed to the genus Munida, two to the genus Paramunida, one to the genus Plesionida, and the last species was ascribed to the genus Agononida. These eight species are described along with phylogenetic relationships at the genus level. Our findings support the taxonomic status of the new species, yet the phylogenetic relationships are not yet fully resolved. Further molecular analysis of a larger data set of species, and more conserved genes, will help clarify the systematics of this group. © 2009 The Linnean Society of London, Zoological Journal of the Linnean Society, 2009, 156 , 465–493.     

Serotonin alters decisions to withdraw in fighting crayfish, Astacus astacus: the motivational concept revisited

The biogenic amine serotonin is thought to play an important role in aggression in many species, including man. This paper summarizes experimental approaches which attempt to link this neuromodulator with fighting in a crayfish model for which the complex agonistic behavior is well characterized. Based on a quantitative analysis of fighting we demonstrate that the infusion of small amounts of serotonin into freely-moving crayfish alters fighting behavior by specifically interfering with the timing of a treated animal's decision to withdraw from an encounter. In the presence of added serotonin, fights last considerably longer compared to controls, but no changes were detected in the rules of escalation, the likelihood of initiating an interaction, or its eventual outcome. Attempts to dissect the underlying neuronal mechanisms pharmacologically hinged on fluoxetine as a potent inhibitor of serotonin re-uptake. Although no behavioral changes were associated with acute infusion of fluoxetine alone, in combination with serotonin it effectively prevented the previously observed fight-enhancing effects. Our data strongly support the significance of functional amine re-uptake mechanisms for behavior and continued use of this invertebrate model should prove a promising route to unravel further the complex bases of aggression. Accepted: 11 October 1997     

雄性黄山短尾猴(Macaca thibetana)攻击支持雌性以换取交配回报

生物市场理论认为动物个体之间通过某种协定交换有价值的商品,使双方均受益。该研究采用目标动物法、行为取样法和连续记录法,对浮溪黄山野生猴谷鱼鳞坑短尾猴(Macaca thibetana)A1群(YA1群)和A2群(YA2群)成年个体在非繁殖季节(2011年8月—12月)和繁殖季节(2012年2月—5月)的雄性攻击支持雌性行为和交配行为进行研究,探讨雄性攻击支持雌性与交配之间的关系。两猴群在繁殖季节和非繁殖季节雄性攻击支持雌性与交配行为均呈显著正相关;YA2群繁殖季节与非繁殖季节攻击支持后交配频次均显著高于随机交配;YA1群在繁殖季节攻击支持后交配频次与随机交配频次差异不显著,但在非繁殖季节攻击支持后交配频次显著高于随机交配,说明短尾猴成年雄性攻击支持雌性可以换取与该雌性个体的交配回报。本研究验证了生物市场理论中社会行为存在交换,首次证明了雄性攻击支持可以换取雌性的交配回报,为进一步研究雄性性竞争与雌性选择提供了实例。     

Seasonal changes in territoriality and frequency of agonistic behavior in two densities of juvenile brown bullhead,Ictalurus nebulosus

Synopsis Incidence of territoriality and frequency of six agonistic action patterns of juvenile brown bullhead, Ictalurus nebulosus, were observed in the laboratory over a two year period at two fish densities under conditions of constant light and temperature. High density fish showed little territoriality or agonistic behavior while low density fish displayed an annual cycle of agonistic behavior and territoriality. Agonistic behavior frequency and incidence of territoriality peaked in February and March and were higher the second year when compared with the first.     

The reproductive behavior of the longspine snipefish,Macrorhamphosus scolopax (Syngnathiformes,Macrorhamphosidae)

Synopsis About two hundred Macrorhamphosus scolopax were observed in a large tank and their behavior was videotaped for subsequent analysis. When not disturbed, the fish moved slowly in a head-down position. Spawning in the tank took place in the last two hours before dark. Courting males change color and actively interact aggressively with other males. They push against each other while swimming in parallel or they charge their opponents with their erected dorsal spine directed at them. Courtship begins near the bottom. After following and swimming parallel to the female the two fish unite tightly by their caudal peduncle, with their ventral regions in close proximity and rise slowly in the water column. During the ascent, the genital papilla of the female extends repeatedly and contacts the genital region of the male.     

Effects of egg removal on maternal aggression, biogenic amines, and stress indicators in ovigerous lobsters (Homarus americanus)

In many disparate taxa, including crayfish, a freshwater decapod crustacean, the presence of one's offspring has been shown to be an important variable in the level of maternal aggression. Ovigerous American lobsters (Homarus americanus) show a territorial advantage against nonmaternal females, even though no posthatch care is provided. The eggs are attached to the pleopods (swimmerets) throughout embryogenesis. We evaluated the effect of stripping ovigerous H. americanus females of their eggs on maternal territoriality. In one treatment group, maternal females were stripped of all eggs. Twelve days later, including being individually isolated for an additional 48 h in a test tank, each resident was serially intruded upon by 4 non-maternal conspecific females. An identically treated control group of ovigerous female residents was left intact prior to the serial intrusions. Various biochemical parameters of the stripped and unstripped animals were measured before and after the experimental treatment (or control). The behavioral modulators measured were the biogenic amines, octopamine and serotonin, and the stress indicators were a heat-shock protein (HSP70), methyl farnesoate, and crustacean hyperglycemic hormone. The intact ovigerous residents showed a significant territorial advantage over the intruders, whereas the contest outcomes of stripped residents were reduced to chance. The presence of eggs in maternal H. americanus is therefore necessary for the maintenance of the shelter-related territorial advantage. However, no significant differences in any of the biochemical parameters were observed between or within treatment conditions. It appears that these amines are not prominently involved in the mechanism of maternal aggression, and that these changes in territorial defense are not simply due to changes in general stress as a result of stripping the females of their eggs.     

The ovarian maturation cycle of the Norway lobster Nephrops norvegicus (Linnaeus, 1758) (Crustacea,Decapoda) from the western Mediterranean Sea

Summary

The Norway lobster Nephrops norvegicus lives in the continental margins of the western Mediterranean Sea at depths between 100 and 600 m. It constitutes an important fisheries resource and presents a seasonal reproductive pattern. Female Norway lobsters were obtained each month from a vessel fishing off Barcelona. One hundred females caught in June 2002 were kept in the laboratory. After spawning, ovarian samples were taken every 30 days with the objective of monitoring the first steps in ovarian maturation. The gonado-somatic index (GSI) remained low over the 6 months during which the females carried their eggs, plus for a further 2–3 months. However, this study suggests that ovarian maturation is a continuous process with two different phases, taking at least 6–8 months during which the female carries its eggs. There is an increase in oocyte numbers; the germinal zone produces oogonia; and the oocytes that develop migrate to the periphery, pushing the post-ovulatory follicles to the wall of the ovary and reinforcing it for subsequent spawning. Besides this increase in the number of oocytes, vitellogenesis begins 2–3 months after the eggs hatch. Oocytes then grow and the ovaries gain weight and change from a cream color to a blackish-green. When the GSI reached 10, spawning occurred and, from then on, the ovary is mainly composed of post-ovulatory follicles.     

Effects of egg removal on maternal aggression,biogenic amines,and stress indicators in ovigerous lobsters (Homarus americanus)

In many disparate taxa, including crayfish, a freshwater decapod crustacean, the presence of one’s offspring has been shown to be an important variable in the level of maternal aggression. Ovigerous American lobsters (Homarus americanus) show a territorial advantage against nonmaternal females, even though no posthatch care is provided. The eggs are attached to the pleopods (swimmerets) throughout embryogenesis. We evaluated the effect of stripping ovigerous H. americanus females of their eggs on maternal territoriality. In one treatment group, maternal females were stripped of all eggs. Twelve days later, including being individually isolated for an additional 48?h in a test tank, each resident was serially intruded upon by 4 non-maternal conspecific females. An identically treated control group of ovigerous female residents was left intact prior to the serial intrusions. Various biochemical parameters of the stripped and unstripped animals were measured before and after the experimental treatment (or control). The behavioral modulators measured were the biogenic amines, octopamine and serotonin, and the stress indicators were a heat-shock protein (HSP70), methyl farnesoate, and crustacean hyperglycemic hormone. The intact ovigerous residents showed a significant territorial advantage over the intruders, whereas the contest outcomes of stripped residents were reduced to chance. The presence of eggs in maternal H. americanus is therefore necessary for the maintenance of the shelter-related territorial advantage. However, no significant differences in any of the biochemical parameters were observed between or within treatment conditions. It appears that these amines are not prominently involved in the mechanism of maternal aggression, and that these changes in territorial defense are not simply due to changes in general stress as a result of stripping the females of their eggs.