Number Of Claws Research Articles

Sustained ecological impacts of invasive crayfish following claw injury

ABSTRACT Human activities have significantly accelerated the translocation of species outside their native range with severe consequences for global biodiversity. Freshwater crayfish are a particularly successful group of invasive species, as exemplified by the increasingly widespread marbled crayfish Procambarus virginalis Lyko, 2017. A significant portion of crayfish populations has regenerating or missing claws. At the same time, claws play important roles in crayfish feeding and intraspecific interactions, altering their ability to invade new areas and impact native communities. Here, using functional response analyses, we combined laboratory experiments and modeling to investigate whether the number of claws on marbled crayfish modulates its ecological impact (focusing on predation rate) as well as its intraspecific interactions via population dynamic modeling. We found that the number of claws did not affect the marbled crayfish’s functional response type (hyperbolic type II), attack rates, or handling times when preying on chironomid larvae. Rates of partial prey consumption were overall low (<2%), and claw number had a significant effect on the partial consumption rate of prey, which tended to increase with the number of claws and prey density. The presence of multiple intraspecific predators influenced marbled crayfish non-trophic behavior, with antagonistic effects prevalent between crayfish pairs regardless of claw status. Moreover, the impact of multiple predators was prey density-dependent, with the highest levels of antagonism shown at the lowest prey density across crayfish groups. Our findings indicate that the ecological influence of invasive crayfish remains unchanged by the number of claws, highlighting the escalating, context-independent threat these species pose to freshwater ecosystems.

A comparison of claw removal methods on the survival and claw regeneration of stone crab (Menippe mercenaria)

Commercial and recreational stone crab (Menippe mercenaria) fisheries primarily occur along the Gulf of Mexico and Atlantic coasts of the southeastern United States and the northeastern Caribbean. The fishery is unique in that only the crabs claws are retained and the animal is returned to the water alive. While the fishery is often regarded as sustainable because it is believed to exploit the crabs natural ability to voluntarily drop (autotomize) and regenerate lost claws, the survival of de-clawed stone crabs is often low, especially when both claws are harvested. In this study, a controlled laboratory experiment was used to compare an induced-autotomy method of claw removal to the typical forced break method currently used in the fishery. For the two different claw removal methods, we compared crab survival and start time to claw regeneration as a function of one or both claws removed. Overall, we found a significant effect of the removal method and number of claws removed on crab survival, but these factors did not influence the time to start claw regeneration. Although the induced-autotomy method was several seconds slower in processing time than the typical forced break method, it resulted in a 29% increase in survival (up to 92% survival throughout the study) compared to the typical forced break method of claw removal (63% survival throughout the study). Overall, these results suggest that the induced-autotomy method of claw removal significantly increases survival of stone crabs.

The Political Character Inherent in the Dragon Decoration of the Palaces during the Reign on King Kojong: through the Number of Claws and Decoration Techniques

The Political Character Inherent in the Dragon Decoration of the Palaces during the Reign on King Kojong: through the Number of Claws and Decoration Techniques

Intraspecific variation in digit reduction in Testudo: the case of the Hermann’s tortoise

Phalangeal reduction is a common and widespread phenomenon among tortoises that has been associated with the adaptation to terrestrial life. While reduced manual digit 1 appears characteristic in almost all Testudo species, it is uncertain why the metacarpal I and distal carpal of the same digit are completely missing in some individuals of Hermann’s tortoise (Testudo hermanni hermanni). To clarify this issue, we investigated the number of manual claws in six populations of Hermann’s tortoise (one from the Ebro Delta in the Iberian Peninsula and five from Minorca Island), their age, sex, genetic lineage, and the substrate type that they inhabit. The number of claws was ascertained based on direct counts (n > 1500 individuals) and by X-rays (n = 32 individuals), obtaining three different phalangeal formulae: (1-2-2-2-1, D-2-2-2-1, 0-2-2-2-1). Thus, claw counts through both methodologies (direct count and X-ray) further confirm that the observed claws serve as a good proxy to assess the actual number of digits. Our results show no loss of phalanges, metacarpal and carpal bones in digit 1 associated with age, sex, or substrate, contrary to some previous authors who hypothesized a relationship between this loss and sexual dimorphism. Therefore, variations in the number of manual digits and the loss of metacarpal I and distal carpal in digit 1 in Hermann’s tortoise are related to population and genetic lineage. More detailed comparisons with other Testudo hermanni populations from elsewhere in Europe would be required to understand the evolutionary significance concerning the intrapopulation variability in the number of digits remaining.

Effects of intrapopulation phenotypic traits of invasive crayfish on leaf litter processing

The impact of invasive alien species (IAS) on an ecosystem is primarily studied at the species level, whereas the functional impacts of their genetic and phenotypic traits are poorly investigated. We used two laboratory based experiments to assess how intrapopulation phenotypic traits (size, sex, and number of claws) of the invasive red swamp crayfish Procambarus clarkii affect invertebrate shredders and leaf processing. Leaf consumption was significantly affected by the size and number of claws but not by the sex of the crayfish. Bigger animals presented a higher overall consumption but, in contrast, the mass of leaves consumed per unit crayfish body mass decreased with size. Indeed, the production of particulate organic matter followed the same trend, suggesting that the higher metabolic needs of smaller animals are responsible for their higher feeding activity on leaf litter. Claw loss in P. clarkii also led to increased leaf consumption and may be related to increased energy requirements for claw regeneration. Our results highlight the importance of also considering the phenotypic traits within populations for better understanding the impacts of IAS on ecosystem processes.

Morphological ontogeny of Protoribates dentatus (Acari, Oribatida, Haplozetidae)

The morphological ontogeny of Protoribates dentatus (Berlese, 1883) is described and illustrated. The juveniles of P. dentatus are elongated, oval in cross section, and their prodorsal, gastronotal setae and most setae on the legs are thin, smooth or with short barbs, which is typical of xylophages. Typical for this group is also a posterior position of the anal opening and relatively thick leg segments and claws, especially on leg I. The larva of P. dentatus has 11 pairs of gastronotal setae, including h2;and setae c2, la and lm are with excentrosclerites. The nymphs have 15 pairs of setae, of which c2, l- and h-series are with excentrosclerites. The adult of this species has a long seta ad1 (which is short in most congeners) and the number of claws varies on all leg tarsi.

Echiniscoides rugostellatusa new marine tardigrade from Washington, U.S.A. (Heterotardigrada: Echiniscoidea: Echiniscoididae: Echiniscoidinae)

Abstract The first new species of tardigrade in the family Echiniscoididae from the west coast of America is presented with an integrative description. Echiniscoides rugostellatus n. sp. was found on barnacles from a piling, in the Straits of Juan Fuca, Puget Sound, Port Townsend, Washington, USA. The new species is named after its granulated dorsal cuticle and the star-shaped tip of its internal and external cirri. The new species is separated from all other Echiniscoides by its granulated cuticle with flat patches, the number of claws on the legs of the adult and the structure of the buccal cirri.

A field assessment of claw removal impacts on the movement and survival of stone crabs Menippe spp.

Claw-only crab fisheries are often marketed as renewable because crabs are returned to the water after declawing to regenerate claws and re-enter the fishery. The challenge of managing a claw-only fishery for stone crabs (Menippe spp.) is compounded by varying regulations throughout their range that include the number of claws harvested from a crab and use of a seasonal closure to protect spawning females. We conducted mark-recapture studies to examine crab responses to claw removal in the field and compared claw handedness and type (crusher, intermediate, pincer) in a wild population to commercial landings to examine compliance with fishery regulations in a one-claw fishery with no seasonal closure. Declawed crabs were recaptured less frequently than control crabs, particularly if claw removal created large wounds. Control crabs were more commonly recaptured within one month of tagging and declawed crabs recaptured one to three months after tagging, suggesting that declawed crabs were less mobile or less motivated to feed initially after claws were harvested and that, over time, intact crabs left the study area. Crabs with fishery-related, regenerated claws comprised 3% of crabs with legal claws. Claw type ratios in a limited assessment of the commercial catch most closely reflected expected ratios consistent with a two-claw fishery, indicating that voluntary adherence to current one-claw fishing regulations is not universal. In fisheries needing better protection of spawning stock, a seasonal closure on fishing could be instituted to ensure better protection of spawning.

Data from new taxa inferIsoechiniscoidesgen. nov. and increase the phylogenetic and evolutionary understanding of echiniscoidid tardigrades (Echiniscoidea: Tardigrada)

The marine heterotardigrades belonging to Echiniscoididae inhabit a wide range of substrates and represent the dominant tardigrade group in intertidal zones worldwide. Notably, the evolution of this family is interesting as it holds key evidence as to how heterotardigrades colonized terrestrial and freshwater environments. We inferred the phylogeny of Echiniscoididae using 28S and COI sequences from GenBank and from new specimens collected at Roscoff, France. Morphological characterizations of several major clades, inferred from the molecular data, are currently lacking. However, one of the clades is erected as a new taxon, Isoechiniscoides gen. nov., for the former Echiniscoides higginsi-group, which comprises species with isonych claws, pillars in the epicuticle and exceptionally long sensory appendages. The type species for the new genus is described here as Isoechiniscoides sifae nov. gen., sp. nov. Isoechiniscoides comprises six clawed interstitial species, whereas Echiniscoides taxa possess a higher claw number and primarily inhabit algae, barnacles and lichens in tidal zones. The new genus, Isoechiniscoides, together with morphologically undetermined specimens from British Columbia (Canada), is sister-group to all other Echiniscoididae taxa. Consequently, we propose to establish Isoechiniscoidinae subfam. nov. to accommodate the new genus. Isoechiniscoidinae provides an evolutionary link between Echiniscoidea and Arthrotardigrada. The latter comprises exclusively marine and mostly interstitial species.

Redescription of Bythotrephes arcticus Lilljeborg, 1901 (Crustacea:Cladocera: Onychopoda) and confirmation of an independent species status of the distant Transcaucasian populations of the genus Bythotrephes Leydig.

Two species of the genus Bythotrephes Leydig, B. arcticus Lilljeborg and B. transcaucasicus Behning, forming a group of close species, are redescribed on the basis of type material and other materials from Northern Eurasia. They were investigated with the application of detailed morphological analysis, including intra- and interpopulation variability and the original scheme of morphometric measurements. The lectotypes and paralectotypes of the species were selected. B. arcticus compared with other species of the genus, seem more evolutionary primitive and less specialized, judging from its large body size, comparatively short tl I, short and straight caudal process, well developed distal setae on two proximal endopodital segments of tl I, and large number of claws. B. arcticus tends to occur in small and shallow water bodies, while B. transcaucasicus was predominantly found in pelagic zone of large and deep Transcaucasian lakes. B. arcticus is probably mainly distributed along the tundra and northern forest area of the Eurasian continent and the nearest islands from Scandinavia to Eastern Siberia. Its documented easternmost locality is situated near the northern part of the Yenisei River, whereas B. transcaucasicus was recorded in the second half of 19th-first half of 20th century in three closely situated mountain lakes in Turkey, Georgia, and Armenia. The presence of B. arcticus in Northern Kazakhstan and B. transcaucasicus in the distant Transcaucasia is linked with their (or their ancestor) hypothetical displacement to the south in the period of ice ages. More recent surveys of Transcaucasian lakes have not revealed the presence of B. transcaucasicus. The rare findings of this species in the past can imply that it could also be missed in the process of collecting but, on the other hand, it cannot be excluded that B. transcaucasicus become extinct as a result of an anthropogenic or other impact on Transcaucasian lakes.

The effect of temperature on release mortality of declawed &lt;I&gt;Menippe mercenaria&lt;/I&gt; in the Florida stone crab fishery

The stone crab, Menippe mercenaria (Say, 1818), fishery off Florida removes claws and releases the crabs to regenerate new claws and potentially re-enter the fishery. An in situ catch-and-release study was conducted during the 2011–2012 fishing season to refine estimates of release mortality. In this study, mortality estimates accounted only for mortality the crab incurred while in a holding pen, which excluded possible predation. The mortality estimates can be considered the minimum mortality that may occur from declawing. Across all samples, 12.8% of crabs died when no claws were removed, 40.8% when one claw was removed, and 62.9% when both claws were removed. Break type, temperature, and number of claws removed were significant variables in a generalized linear mixed model with random effects for region and station. The odds of dying increased by a factor of 1.33 for each degree increase in temperature, of 2.29 when both claws were removed compared with one claw removed, and 6.10 when a break was proximal of the basiischium (BI) compared with a break along the BI. Temperature ranged from 12.2 to 28.1 °C during the study, however, the predicted mortality across all treatments suggests release mortality may increase with climate induced warming of sea temperatures. The temperature effect observed suggests that release mortality rates are high throughout the fishing season in the southern region (>60% of landings) and early and late in the season in the central and northern regions when waters were warm (>20 °C).

The Consequences of Claw Removal on Stone Crabs Menippe spp. and the Ecological and Fishery Implications

AbstractThe practice of claw removal in the fishery for stone crab Menippe spp. can affect fished populations in an atypical way because harvested individuals are not necessarily killed. In all stone crab fisheries, crabs are returned to the water after their claws are harvested with the expectation that claws may be regenerated, thus “renewing” the fishery. The number of legal‐sized claws that can be removed from an individual differs (with local regulations) throughout the stone crabs' range. We examined the direct and indirect consequences of removing one and two claws by monitoring mortality and prey consumption in the short term (14 d) and mortality and growth over the long term (11 months). Claw removal induced mortality within days when wound widths were greater than 7 mm, regardless of the number of claws removed. Wound widths created by autotomy were similar to those created by a clean, forced break along the natural fracture plane. These results suggest that direct mortality following claw removal may be low in a two‐claw fishery for stone crabs that do not incur large wounds; however, indirect effects that result from altered feeding abilities may be substantial. Stone crabs with one claw removed (the crusher) consumed fewer bivalves than control (intact) crabs, whereas stone crabs with two claws removed did not consume any bivalves but ate fish flesh. Consequently, bivalves, an important prey resource throughout the stone crabs' geographical range, are eliminated from a clawless crab's diet until its claws are regenerated. No stone crabs regenerated a legal‐sized claw on the first molt after claw removal, and no stone crabs larger than 104 mm carapace width molted within 11 months. Thus, the long intermolt duration of legal‐sized stone crabs and the reduced prey consumption for stone crabs that lost claws indicate that the return to the fishery of previously harvested stone crabs is probably an uncommon occurrence.Received December 17, 2014; accepted June 15, 2015

Morphology, distribution and certain population parameters of the Arctic mite Oribatella arctica (Acari: Oribatida: Oribatellidae)

In this study, the morphology, distribution, ecology, stage structure and sex ratio of the Arctic oribatid mite Oribatella arctica (Thor, 1930) were investigated. The juveniles of this species are similar to those of other species of Oribatella Banks, 1895, possessing mostly long and barbed prodorsal setae, long and barbed gastronotal setae in the larva and long, barbed peripheral gastronotal setae in the nymphs. The larva of O. arctica differs from that of most other Oribatella species principally by the shape of the sensillus and the length of seta le. Nymphs differ chiefly by the number and shape of some central setae (c1 and d-series) on the gastronotum and the attachment of the exuvial scalps of previous instars to the gastronotum. All nymphs of O. arctica have central setae c1, da and dm short and smooth, whereas the presence and shape of seta dp varies between nymphal stages (it can be long and barbed, short and smooth, alveolar or absent). Oribatella arctica nymphs rarely carry the exuvial scalps on the gastronotum, but if so, these scalps are fastened to the gastronotum, using setae c1, c2 and of l-series, whereas most of other species of Oribatella carry the exuvial scalps, using special muffs that are formed while moulting on the apical parts of setal pair da. The adult of O. arctica appears initially similar to other species of Oribatella, but differs mainly in the shape of the lamella and lamellar cusps, presence of translamella, shape of the sensillus, length of most notogastral setae, location of setae lp, h2 and h3, body size, number of claws on legs, and shape of epimeral seta 4c.

Echiniscoides wyethi, a new marine tardigrade from Maine, U.S.A. (Heterotardigrada: Echiniscoidea: Echiniscoididae)

Abstract A new species of tardigrade in the family Echiniscoididae, Echiniscoides wyethi, was found on the barnacle Semibalanus balanoides (L.) at several intertidal sites around Allen Island, Maine, USA. The new species is named after the American artist Andrew Wyeth and the Wyeth family who own the island on which this species was discovered. The new species is separated from all other Echiniscoides by the smooth cuticle, long flexible buccal tube, and the number of claws on the legs of the adult.

The impact of different planting methods on yield and yield component of wheat cultivar Chamran under different conditions of irrigation in the Northern Khuzestan Climate

This paper aims at investigating the impacts of different planting methods on the yield and yield component in different irrigation conditions on wheat (cultivar of Chamran) in Khuzestan for one year in Shavoor agricultural farm located in 70 km north of Ahvaz which lies in E longitude 48˚:28 and N latitude 31˚:50 as split plots in a randomized complete blocks design with three replications. The main factor is planting method in two levels of linear and sprinkling, and the subsidiary factor comprises irrigation treatments and dry farming. Variance analysis results revealed that in both factors there is a significant effect in all characteristics except for 1000grain weight which is dependent upon genotype, while the interaction of the two factors was significant only on the characteristics of panicle number per square meter and seed number in each panicle. By examining the comparison of grain yield means and other agricultural traits, the highest significant numeric value belongs to linear planting, except for the panicle number per square meter that had completely reverse trends in both treatments. Ultimately it is concluded that besides economic considerations through decreasing the amount of seeds needed and the easier control of weeds, linear planting helps to increase grain yield by accurately adjusting the distance and depth with regard to the proper positioning of seeds through increasing the claw number and other relevant characteristics of performance.

Ostracod genus Parapolycope (Crustacea): Diversity, distribution, and phylogeny, with description of the first representative from Korea

ParapolycopeKlie, 1936 belongs to the family Polycopidae, one of the ecologically most diverse and morphologically most primitive ostracod families. Due to the small size of animals, polycopids are poorly studied and unknown in many regions of the world. We describe a new species, Parapolycope koreana sp. nov., from marine beach interstitial in Gyeongsangnam-do, South Korea. This is the first representative of the genus, and the first named polycopid species from Korea. It is very closely related to several species from marine interstitial in Japan, but differs mainly in the shape and ornamentation of the shell and morphology of the male upper lip. A cladistic analysis of the genus Parapolycope is performed to test the phylogenetic relationships between species. Although Parapolycope presently encompasses 18 species, only 15 are included in the analysis, because Parapolycope seridentata (Hartmann, 1959), Parapolycope ramunchensis (Hartmann-Schröder and Hartmann, 1962), and Parapolycope minutissima (Hartmann, 1974) differ so much from other congeners that they should be excluded from the genus. The analysis is based on 27 morphological characters, with Parapolycopissa rossica (Chavtur, 1977) and Polycopiella microdentataChavtur, 1979 as two outgroup taxa. In spite of the fact that descriptions of almost half of species included in the analysis are based on a limited set of morphological characters, the majority rule of the 15 equally parsimonious trees undoubtedly shows that there are at least two distinct lineages in the genus, defined by the number of claws on the female uropodal lamellae. A close relationship between the new species and the Japanese congeners is also strongly supported. We redescribe the type species of the genus, Parapolycope germanicaKlie, 1936, based on the type material, and designate the lectotype and paralectotypes. A key for identification of Parapolycope species is provided, along with a map of their distribution. This is a cosmopolitan taxon, with the centre of diversity in the Northwest Pacific region.

Thambema thunderstruckae sp. n., the first record of Thambematidae (Isopoda: Asellota) from the Southern Hemisphere shelf

Thambema thunderstruckae sp. n., the first record of Thambematidae (Isopoda: Asellota) from the Southern Hemisphere shelf A new thambematid species, Thambema thunderstruckae sp. n., is described from King George Island, South Shetland Islands, Antarctic. Specimens of the new species were collected during two Polish Antarctic Expeditions in 1985 and 2007. It is the first record of this family from the Southern Hemisphere. The new species most closely resembles Thambema golanachum Harrison, 1987 and T. fiatum Harrison, 1987 but can be distinguished from both species by the shape of male pleopod 1, the number of claws on pereopods 2-7 and the setation of pereopod 1 and 2 carpus, respectively. A key to all known genera and species in the family Thambematidae is also provided.

Cubicity of interval graphs and the claw number

AbstractLet G(V, E) be a simple, undirected graph where V is the set of vertices and E is the set of edges. A b‐dimensional cube is a Cartesian product I1×I2×···×Ib, where each Ii is a closed interval of unit length on the real line. The cubicity of G, denoted by cub(G), is the minimum positive integer b such that the vertices in G can be mapped to axis parallel b‐dimensional cubes in such a way that two vertices are adjacent in G if and only if their assigned cubes intersect. An interval graph is a graph that can be represented as the intersection of intervals on the real line—i.e. the vertices of an interval graph can be mapped to intervals on the real line such that two vertices are adjacent if and only if their corresponding intervals overlap. Suppose S(m) denotes a star graph on m+1 nodes. We define claw number ψ(G) of the graph to be the largest positive integer m such that S(m) is an induced subgraph of G. It can be easily shown that the cubicity of any graph is at least ⌈log2ψ(G)⌉. In this article, we show that for an interval graph G ⌈log2ψ(G)⌉⩽cub(G)⩽⌈log2ψ(G)⌉+2. It is not clear whether the upper bound of ⌈log2ψ(G)⌉+2 is tight: till now we are unable to find any interval graph with cub(G)&gt;⌈log2ψ(G)⌉. We also show that for an interval graph G, cub(G)⩽⌈log2α⌉, where α is the independence number of G. Therefore, in the special case of ψ(G)=α, cub(G) is exactly ⌈log2α2⌉. The concept of cubicity can be generalized by considering boxes instead of cubes. A b‐dimensional box is a Cartesian product I1×I2×···×Ib, where each Ii is a closed interval on the real line. The boxicity of a graph, denoted box(G), is the minimum k such that G is the intersection graph of k‐dimensional boxes. It is clear that box(G)⩽cub(G). From the above result, it follows that for any graph G, cub(G)⩽box(G)⌈log2α⌉. © 2010 Wiley Periodicals, Inc. J Graph Theory 65: 323–333, 2010

Boxicity and cubicity of asteroidal triple free graphs

The boxicity of a graph G , denoted box ( G ) , is the least integer d such that G is the intersection graph of a family of d -dimensional (axis-parallel) boxes. The cubicity, denoted cub ( G ) , is the least d such that G is the intersection graph of a family of d -dimensional unit cubes. An independent set of three vertices is an asteroidal triple if any two are joined by a path avoiding the neighbourhood of the third. A graph is asteroidal triple free (AT-free) if it has no asteroidal triple. The claw number ψ ( G ) is the number of edges in the largest star that is an induced subgraph of G . For an AT-free graph G with chromatic number χ ( G ) and claw number ψ ( G ) , we show that box ( G ) ≤ χ ( G ) and that this bound is sharp. We also show that cub ( G ) ≤ box ( G ) ( ⌈ log 2 ψ ( G ) ⌉ + 2 ) ≤ χ ( G ) ( ⌈ log 2 ψ ( G ) ⌉ + 2 ) . If G is an AT-free graph having girth at least 5 , then box ( G ) ≤ 2 , and therefore cub ( G ) ≤ 2 ⌈ log 2 ψ ( G ) ⌉ + 4 .

Cubicity of Interval Graphs and the Claw Number

Abstract Let G ( V , E ) be a simple, undirected graph. A b-dimensional box is a Cartesian product I 1 × I 2 × ⋯ × I b , where each I i is a closed interval on the real line. When each interval has unit length we have a b-dimensional cube. The cubicity (respectively boxicity) of G, cub ( G ) ( box ( G ) ) is the minimum positive integer b such that the vertices in G can be mapped to axis parallel b-dimensional cubes (boxes) in such a way that two vertices are adjacent in G if and only if their assigned cubes (boxes) intersect. Suppose S ( m ) denotes a star graph on m + 1 nodes. We define claw number ψ ( G ) to be the largest positive integer m such that S ( m ) is an induced subgraph of G. In this paper we show that for an interval graph G ⌈ log 2 ψ ( G ) ⌉ ⩽ cub ( G ) ⩽ ⌈ log 2 ψ ( G ) ⌉ + 2 . We also show that cub ( G ) ⩽ ⌈ log 2 α ⌉ , where α is the independence number of G. From this we have, for any graph G, cub ( G ) ⩽ box ( G ) ⌈ log 2 α ⌉ .