The feeding behaviour of the sand crab Scopimera inflata (Decapoda, Ocypodidae)

A sequence of activities all related to the feeding of Scopimera inflata H. Milne-Edwards, 1873 can be distinguished during the daytime periods of low tide. Emergence begins one to two hours after a feeding area is uncovered, reaches a peak after a further three hours but some crabs are still emerging after the tide has turned. Before feeding commences the burrow is cleared of waste sand down to the water-table. While feeding S. inflata forms a feeding trench which acts as an escape route back to the hole and is defended against other crabs of the same species. Agonistic behaviour becomes evident as feeding progresses. Threat displays, fighting, displacement feeding, and agitation feeding are recognizable behaviour patterns which have been observed.     

Are females of Ilyoplax pusilla (Brachyura: Dotillidae) attracted to groups having more waving males?

Males of the dotillid crab Ilyoplax pusilla wave at approaching females during the breeding season. They also, however, often perform waving that is not directed toward any particular individual. This undirected waving is associated with the presence of male neighbors and may function in male–male competition. It may also, however, act as a long-range female attractant. To test whether undirected waving functions to attract females, we conducted a field experiment that manipulated the abundance of waving males. We found that females preferred to approach groups that had more waving males. This suggests that undirected waving by male I. pusilla functions as a long-range courtship signal.     

Male courtship cycles in three species of tropical Ilyoplax crabs (Decapoda,Brachyura, Ocypodidae)

The courtship behaviour and cycles of male courtship activity and colouration of Ilyoplax orientalis, I. delsmani and I. gangetica were studied in the field in Malaysia and Thailand. Each species had a distinctive chela waving or beckoning display. Depending on species, the chelipeds, carapaces, or both of waving males blanched to white in contrast to the cryptic colour of nonwaving males and females. All three of these tropical Ilyoplax exhibited semilunar cycles in male waving activity at the colony level. It was confirmed for I. orientalis that individual males cycled each semilunar period between waving and non-waving phases and exhibited different behaviour toward females during these two behavioural phases.     

The language of lizards: interpreting the function of visual displays of the Indian rock lizard, Psammophilus dorsalis (Agamidae)

The first step in understanding any communication system is to document signal diversity relative to the context of signalling (e.g. sex of the signaller and audience). Observation of 30 free-ranging rock lizards (Psammophilus dorsalis) on rock outcrops in southern India over a period of 18 months revealed that these lizards produce a complex array of ritualized signals involving push-ups (head-bobbing), dorsal flattening, extension of the legs or gular region, and tail-raising. Push-ups were performed by both sexes, usually after moving from one location to another. Push-ups were rarely accompanied by other postural modifications, and seem to function as non-directed signals. Dorsal flattening was elicited by birds flying overhead, and seems to make the lizard less conspicuous to predators. There was, nonetheless, a strong sex difference in the frequency of this behaviour, because the habitats used by males (open rocks) exposed them to more birds. Males displayed to females by extending their gular folds and arching their backs; other animals (e.g. squirrels, monkeys) also elicited the latter posture from both sexes. Leg extension was observed for both males and females, but in different contexts—males in response to conspecifics, females in response to other animals. Females raised their tails in response to encountering a male. Thus, these lizards have a complex repertoire of postures for predator evasion, for interaction with other species and with conspecifics, and for communicating sex-specific social information about gender (tail-raise) or dominance status (gular extension, leg extension).     

Selection of IgE-binding aptameric green fluorescent protein (Ap-GFP) by the ribosome display (RD) platform

GFP-Cκ fusion protein was previously shown selectable on ribosome display platform with solid phase antibodies against GFP determinant [Y.-M. Yang, T.J. Barankiewicz, M. He, M. Taussig, S.-S. Chen, Selection of antigenic markers on a GFP-Cκ fusion scaffold with high sensitivity by eukaryotic ribosome display, Biochem. Biophys. Res. Commun. 359 (2007) 251-257]. Herein, we show that members of aptameric peptide library constructed within the site 6 and site 8/9 loops of GFP of the ribosome display construct are selectable upon binding to the solid phase IgE antigen. An input of 1.0 μg of the dual site aptameric GFP library exhibiting a diversity of 7.5 × 10¹¹ was transcribed, translated and incubated with solid phase IgE. RT-PCR products were amplified from mRNA of the aptamer-ribosome-mRNA (ARM) complex captured on the solid phase IgE. Clones of aptameric GFP were prepared from RT-PCR product of ARM complex following repetitive selection. Recombinant aptameric GFP proteins from the selected clones bind IgE coated on the 96-well plate, and the binding was abrogated by incubation with soluble human IgE but not human IgG. Selected aptameric GFP proteins also exhibit binding to three different sources of human IgE (IgE PS, BED, and JW8) but not irrelevant proteins. These observations indicate that appropriately selected aptameric GFP on a solid phase ligand by ribosome display may serve as an affinity reagent for blocking reactivity of a biological ligand.     

Molecular phylogeny of grapsoid crabs (Decapoda, Brachyura) and allies based on two mitochondrial genes and a proposal for refraining from current superfamily classification

Grapsoid and ocypodoid crabs receive a lot of attention in the literature due to their predominance and important role as primary and secondary consumers in intertidal as well as supratidal marine habitats. They are especially species‐rich in the tropics, where they have been found to repeatedly invade terrestrial and freshwater habitats. However, the systematics of the crabs belonging to these two superfamilies is still not settled, despite recent steps clarifying phylogenetic relationships and introducing new taxa. In this study, a molecular phylogeny of grapsoid crabs primarily based on East African representatives is constructed based on DNA sequences of the mitochondrial small and large ribosomal subunits (12S and 16S rRNA), thus complementing previous molecular taxonomic studies that had been carried out with the American and East Asian fauna. In addition, selected representatives of all ocypodoid families and subfamilies were included. The monophyly of Grapsidae, Ocypodidae (sensu stuctu), Sesarmidae and Varunidae is well confirmed, if the genera Cyclograpsus, Helice are considered Varunidae and Euchirograpsus a Plagusiidae, as previously suggested. The monophyly of the family Gecarcinidae cannot be supported with our data. The family Plagusiidae in its present composition is polyphyletic. Special attention was given to the large family Sesarmidae, which has many endemic genera in the Indo‐West Pacific. According to this study, two of the most speciose genera, Chiromantes and Parasesarma, are not monophyletic and need to be redefined. On the higher taxonomic level, it becomes evident that both superfamilies, Grapsoidea and Ocypodoidea, are not monophyletic in their current composition, as exemplified by a proposed sister group relationship of Varunidae and Macrophthalmidae. These results confirm those from previous molecular studies and we therefore propose to refrain from the traditional use of the Grapsoidea and Ocypodoidea as monophyletic superfamilies and treat the constituent families separately.     

Investigations on DNA damage and frequency of micronuclei in occupational exposure to electromagnetic fields (EMFs) emitted from video display terminals (VDTs)

The potential effect of electromagnetic fields (EMFs) emitted from video display terminals (VDTs) to elicit biological response is a major concern for the public. The software professionals are subjected to cumulative EMFs in their occupational environments. This study was undertaken to evaluate DNA damage and incidences of micronuclei in such professionals. To the best of our knowledge, the present study is the first attempt to carry out cytogenetic investigations on assessing bioeffects in personal computer users. The study subjects (n = 138) included software professionals using VDTs for more than 2 years with age, gender, socioeconomic status matched controls (n = 151). DNA damage and frequency of micronuclei were evaluated using alkaline comet assay and cytochalasin blocked micronucleus assay respectively. Overall DNA damage and incidence of micronuclei showed no significant differences between the exposed and control subjects. With exposure characteristics, such as total duration (years) and frequency of use (minutes/day) sub-groups were assessed for such parameters. Although cumulative frequency of use showed no significant changes in the DNA integrity of the classified sub-groups, the long-term users (> 10 years) showed higher induction of DNA damage and increased frequency of micronuclei and micro nucleated cells.     

Carapace movements associated with ventilation and irrigation of the branchial chambers in the semaphore crab,Heloecius cordiformis (Decapoda: Brachyura: Ocypodidae)

Summary Carapace movements in crabs are briefly reviewed. While on land and recirculating branchial water, the Australian semaphore crab Heloecius cordiformis (Decapoda: Ocypodidae), a semi-terrestrial air-breathing mangrove crab, sequentially depresses and elevates its carapace relative to its thorax (0.5–1 mm excursion) in a regular pump-like manner. In quiescent crabs each carapace-pumping cycle lasts about 4 s; carapace depression takes 3 s and elevation 1 s. Carapace movements are brought about by pressures generated within the branchial chambers by the scaphognathites, probably in combination with carapace muscles. Carapace movements are associated with bilaterally synchronised scaphognathite activity. Unilateral scaphognathite activity was not observed. During normal forward recirculation of branchial water the scaphognathites beat at about 1.5 Hz (slow-forward pumping) and the lungs (epibranchial chambers) are not ventilated. In Heloecius, the lungs are not physically separated from the gills below by an anatomical barrier. Lung ventilation is accomplished during the following sequence of events: the carapace is lowered and the scaphognathites pump in a fast-forward mode at about 2.8 Hz. This activity preferentially pumps air out of the lungs and generates suction within the branchial chambers (4–10 cm H₂O below ambient) which draws water from external body surfaces into the hypobranchial space below and around the gills. At the end of the carapace's downward travel the scaphognathites switch from fast-forward to fastreverse beating at about 4 Hz. This pumps air into the lungs and the carapace elevates. As a result, during carapace elevation the water which had previously been drawn into the branchial chambers by fast-forward pumping activity is released and flows out between the legs and into the abdominosternal cavity. When the carapace reaches its original resting or up position the scaphognathites switch from fast-reverse to slowforward beating to re-establish water recirculation through the branchial chambers. This cycle is subsequently repeated. In stationary crabs, there are 2 carapace-pumping cycles per minute, increasing to 14 per minute in active crabs (walking). When water is absent, the lungs are preferentially ventilated by slow-reverse scaphognathite pumping activity. Carapace movements do not occur in the absence of branchial water. Carapace pumping is thought to provide a mechanism which permits the scaphognathites to ventilate the lungs in the presence of recirculating branchial water, without this water interfering with lung ventilation or being lost to the environment.Abbreviations FF, FR, SF, SR fast-forward, fast-reverse, slowforward, slow-reverse scaphognathite pumping - MEA Milne Edwards aperture     

The feeding behaviour of a deep-sea holothurian, Stichopus tremulus (Gunnerus) based on in situ observations and experiments using a Remotely Operated Vehicle

Using a Remotely Operated Vehicle (ROV) to deploy an in situ cage experiment incorporating fluorescent Luminophore particle tracers, the gut throughput time of the deposit feeding holothurian, Stichopus tremulus (Gunnerus) was determined as 23.73 h (S.D.±2.3). For a range of individuals examined at different depths (350-500 m) and locations, throughput times varied between 19 and 26 h irrespective of animal size or gut tract length. In situ video observations of feeding behaviour showed that this species uses fine oral papillae in a ‘sweeping’ motion to target particles on the seafloor. Following detection of a food source fine-branched digitate tentacles collect a large range of sediment fragments from the seabed. The main types of particles ingested include silica fragments (<20 >500 μm), pelagic foraminifera, benthic foraminifera, fine phytodetrital remains and occasional larger rock fragments (∼1 cm). Ingested sediment consisted mainly of very fine silica fragments (∼50 μm) accounting for over 50% of the total gut contents. Frame-by-frame video analysis revealed that the particle handling time (i.e. the time taken for a tentacle insertion and the subsequent collection of food) was found to be ∼54 s. Only 10 of the 20 feeding tentacles were simultaneously employed during feeding. Use of tentacles appeared to be in sequence, alternating between the reserve and active tentacles. Estimating the rate of movement over the seabed and the total effective capture area of each tentacle, the impact of this animal on the turnover and quality of surface sediment at this deepwater site is potentially substantial. The in situ experiments provided a significant improvement over previous methods used to investigate deep-sea deposit feeders and represent a useful concept for further in situ deep-sea research using an industrial ROV.     

Floral display size in comfrey, Symphytum officinale L. (Boraginaceae): relationships with visitation by three bumblebee species and subsequent seed set

The fecundity of insect-pollinated plants may not be linearly related to the number of flowers produced, since floral display will influence pollinator foraging patterns. We may expect more visits to plants with more flowers, but do these large plants receive more or fewer visits per flower than small plants? Do all pollinator species respond in the same way? We would also expect foragers to move less between plants when the number of flowers per plant are large, which may reduce cross-pollination compared to plants with few flowers. We examine the relationships between numbers of inflorescence per plant, bumblebee foraging behaviour and seed set in comfrey, Symphytum officinale, a self-incompatible perennial herb. Bumblebee species differed in their response to the size of floral display. More individuals of Bombus pratorum and the nectar-robbing B.?terrestris were attracted to plants with larger floral displays, but B. pascuorum exhibited no increase in recruitment according to display size. Once attracted, all bee species visited more inflorescences per plant on plants with more inflorescences. Overall the visitation rate per inflorescence and seed set per flower was independent of the number of inflorescences per plant. Variation in seed set was not explained by the numbers of bumblebees attracted or by the number of inflorescences they visited for any bee species. However, the mean seed set per flower (1.18) was far below the maximum possible (4 per flower). We suggest that in this system seed set is not limited by pollination but by other factors, possibly nutritional resources.     

Fruit set in Styrax obassia (Styracaceae): the effect of light availability, display size, and local floral density

Maternal reproductive success was examined in Styrax obassia (Styracaceae), a bumble-bee pollinated mass-flowering tree in a cool-temperate deciduous forest in northern Japan. The effects of flower number on the success of individual flowers at three levels (inflorescence, individual, and population) were considered. During 1995 and 1996, variations in size, light availability to branches, floral display size, and fruit set were monitored in 37 out of 211 individual S. obassia trees in a 4-ha forest plot. In addition, the locations of the 211 trees in this plot were mapped and the number of inflorescences in each tree was counted. A multiple regression analysis showed that flower number per inflorescence and inflorescence number per individual had negative effects on fruit set, and inflorescence number of aggregated clumps of flowering trees, tree size, and light resource had positive effects on fruit set although significant level were marginal. It is concluded that pollinator attraction may occur not at the individual tree level, but at the level of a clump of flowering trees. It is also suggested that geitonogamy increased with inflorescence number of tree and inflorescence size and that resource limitation was related to the light condition and variation of tree size.     

Exploitation of floral signals by crab spiders (Thomisus spectabilis, Thomisidae)

Flowers exhibit characteristics through which they exploit thesensory biases of pollinating insects, and both signaler andreceiver benefit from this interaction, either through reproductiveservice or food reward. However, the preferences of pollinatorsfor certain flower traits such as color or odor might be exploitedby predators that target pollinating insects. Crab spiders,Thomisus spectabilis, position themselves on flowers to preyon pollinators such as honeybees, Apis mellifera. We gave bothhoneybees and crab spiders the choice between two randomly chosenwhite Chrysanthemum frutescens, including olfactory signalsin one experiment and excluding odor in a second experiment.When olfactory signals were included, crab spiders and honeybeesclearly preferred the same flower out of a pair. However, agreementlevel was at chance in the absence of olfactory signals. Wealso analyzed the visual flower characteristics that might influencethe decision of the animals. Neither the size of flowers (diameterof flower and diameter of reproductive flower center) nor thereflectance properties (receptor excitation values in ultraviolet,blue, and green; overall brightness) influenced the choicesof crab spiders and honeybees. Therefore, odor seems to be thefloral signal that bees use to identify high-quality flowersand that crab spiders exploit to encounter honeybees.     

The reproductive system of Limnopilos naiyanetri indicates a thoracotreme affiliation of Hymenosomatidae (Decapoda,Eubrachyura)

The eubrachyuran Hymenosomatoidea is widely distributed in tropical and subtropical regions ranging from marine to freshwater habitats. Even though the biology of this taxon has been studied to some extent, its phylogenetic relationships are not resolved. Based on different morphological characters, some authors suggested a close affinity of hymenosomatid crabs to heterotremes. However, many of these characters are ambiguous, and the few molecular studies did not provide convincing solutions either. To address this issue, we studied the reproductive system of the hymenosomatid freshwater species Limnopilos naiyanetri Chuang and Ng, 1991 using histology and scanning electron microscopy. The females show the characteristic organization of the paired eubrachyuran reproductive system. Additionally, a bursa (an accessory sperm storing cuticle cavity) is present. The male copulatory system is characterized by paired long first and short second gonopods, and a pair of sternal gonopores equipped with a penis. Both, the female and male reproductive organs reveal a number of similarities to thoracotreme crabs. The seminal receptacle is lined by a very thin cuticle and by a mono-layered glandular epithelium. The male gonopods and the sternal genital opening also resemble the thoracotreme condition. Thus, our results indicate that Hymenosomatidae are most likely part of the Thoracotremata.     

The wound-healing responses of Antithamnion nipponicum and Griffithsia pacifica (Ceramiales, Rhodophyta) monitored by lectins

The binding of FITC labeled lectins to repair cells of Antithamnion nipponicum Yamada et Inagaki and Griffithsia pacifica Kylin, and their physiological effects on somatic cell fusion have been studied. Results indicate that repair cells strongly bind the lectins ConA and LCA, whereas other lectins did not bind to the cell, The binding of these lectins to the dead cell wall shows ConA and LCA specific substances are secreted from the tip of the repair cells. When fluorescently labeled ConA or LCA was added at various time intervals after wounding, it firstly bound (3 h post-wounding) as a thin layer at the tips of the adjacent cells. Later (4–5 h post-wounding) labeling also appeared at the tips of the repair ceils. Intense labeling at these sites continued throughout the wound-healing process until repair cell fusion, at which time the lectin labeling was reduced to a narrow ring around the area of fusion, When added to plants prior to wounding and with continued monitoring, these same lectins were found to act as inhibitors to the wound-healing response. Other control lectins showed no inhibitory effects. These results suggest that a signal glycoprotein with α-D-mannosyl residues is involved in the wound-healing process of Antithamnion nipponicum. Lectins conjugated with visible tags can be used as a very fast and useful tool to monitor these signal substances.     

Effect of isolation and conspecific presence in a novel environment on corticosterone concentrations in a social avian species, the zebra finch (Taeniopygia guttata)

Zebra finches are a highly social and monogamous avian species. In the present study, we sought to determine the effect of social isolation (separation from the flock) in a novel environment with and without a conspecific present on the adrenocortical activity of paired and unpaired individuals of this species. With regard to paired birds, we hypothesized that the presence of the mate during isolation from the group would act as a social buffer against the stressful effects of isolation. We observed that 10 but not 30 minutes of social isolation resulted in elevated concentrations of corticosterone in unpaired and paired male zebra finches in comparison to baseline concentrations of corticosterone. Furthermore, the presence of a mate during isolation in a novel environment did not have a buffering effect against increases in corticosterone concentrations. Additionally, to compare concentrations of corticosterone in response to isolation (in a novel environment) to a previously well-established stressor, we subjected groups of birds to restraint. We observed that 10 or 30 minutes of restraint led to significantly higher concentrations of corticosterone as compared to baseline. Finally, to rule out the possibility that merely handling a bird would result in significantly elevated concentrations of corticosterone as compared to baseline samples, we measured corticosterone concentrations 10 or 30 minutes after handling involving capture and release only. Our results suggest that handling alone might have contributed to the elevation of corticosterone in birds exposed to 10 minutes but not 30 minutes of restraint. Handling by itself did not account, however, for the elevated corticosterone in birds socially isolated for 10 minutes.     

The benthic phase of the life cycle ofParapenaeus longirostris (Crustacea,Decapoda, Penaeidae) along the Mediterranean coast of Israel

The population ofP. longirostris along the Mediterranean coast of Israel spends the benthic phase of its life cycle (from body size over 15 mm) on muddy bottom deeper than 45 m. New age groups are recruited within the depth zone of 45–300 m and migrate in both inshore and offshore directions. Inshore migration is limited by unsuitable sandy ground. The limiting line for offshore migration was not found.An age group could be detected during one year within a body size range of TL = 40 mm to TL = 84.5 mm for males and to TL = 102.5 mm for females. Reproductive activity in shallow water, down to a depth of 73 m, takes place during the whole year, while in depths of 150–300 m there is an arrest of reproductive activity from June to August.     

The population dynamics of some freshwater carideans (Crustacea: Decapoda) in Hong Kong,with special reference to Neocaridina serrata (Atyidae)

During a 15-month investigation of the population dynamics of three caridean shrimp species in the Lam Tsuen River, New Territories, Hong Kong, the numbers of the commonest species, Neocaridina serrata (Stimpson)(Atyidae), were reduced as water temperatures fell. By contrast, Caridina lanceifrons Yu became more numerous during the winter. The relatively scarce Macrobrachium hainanense (Parisi)(Palaemonidae) tended to be more abundant during the summer, and the abundance of this species was directly correlated with that of N. serrata. The population size of these two species was positively correlated with water temperatures prevailing one and two months prior to the collection of samples, but there was no significant relationship between C. lanceifrons abundance and water temperature.All species exhibited similar growth patterns with an inflection at the attainment of sexual maturity, occurring after the (presumed) 14th moult for N. serrata and in the (presumed) 13th and 18th stadium for C. lanceifrons and M. hainanensis respectively. Ovigerous shrimps of all species were only recorded when water temperatures exceeded 20 °C and the % incidence of ovigerous N. serrata was positively correlated with prevailing temperatures. It is suggested that restriction of freshwater caridean breeding periods by low temperatures may be common in the subtropics while perennial breeding is more likely to be typical of tropical regions.The mean carapace length of N. serrata populations was negatively correlated with prevailing temperatures, but more strongly correlated with temperatures recorded one and two months prior to sampling when gametogenesis may have taken place. Smallest mean sizes were recorded in late summer upon the cessation of juvenile recruitment. N. serrata has a maximum longevity of approximately 12 months and reproduction occurs in the 7th month of life or later. The hatchlings are well developed and clutch size is not related to the size of the brooding female. An annual life cycle, as seen in N. serrata, may be typical of many small freshwater carideans.Department of Zoology, The University of Hong Kong     

The description of a new species of the Neotropical land crab genus Gecarcinus Leach, 1814 (Crustacea,Decapoda, Brachyura,Gecarcinidae)

In this contribution a new species of the land crab genus Gecarcinus Leach, 1814, from the Neotropical Pacific coast of South America is described and illustrated. In addition to its unique body color, Gecarcinus nobiliisp. n. is distinguished from congeners by a distinctly wider carapace front and differences in the shape of the infraorbital margin. The new species is not isolated from Gecarcinus populations from the Pacific coast of Central America by an insurmountable geographic barrier. Considering the closure of the Panamanian Isthmus as a calibration point for morphological divergence between the trans-isthmian mainland populations of Gecarcinus, the virtual lack of morphological differentiation (other than color) between them and the distinctness of G. nobiliisp. n. suggests that G. nobiliisp. n. evolved from a common ancestor before the Isthmus closed.     

The complete mitogenome of the hydrothermal vent crab Xenograpsus testudinatus (Decapoda, Brachyura) and comparison with brachyuran crabs

In this study, we analyzed the complete mitochondrial (mt) genome of a hydrothermal vent crab Xenograpsus testudinatus (Decapoda: Brachyura) obtained from the hydrothermal vents off Kueishantao Island, Taiwan, which extend from the deep sea Okinawa Trench. The mitogenome of X. testudinatus was 15,796 bp in length and contained the same 37 genes (e.g. 2 rRNAs, 22 tRNAs, and 13 PCGs) found in other metazoan mitogenomes. Analysis of the structural mt gene order in X. testudinatus revealed that the 13 PCGs, excluding a translocation of ND6-Cyt b cluster, were similarly ordered when compared to the pancrustacean ground pattern; however the tRNAs were severely rearranged. Phylogenetic analysis of decapod mitogenomes showed that the molecular taxonomy of the vent crab was in accordance with its morphological systematics. Together, these findings suggest that the vent crab studied here has little mitochondrial genetic variation when compared with morphologically defined conspecifics from other marine habitats.