The functioning of female genitalia in many arthropods, especially the site and mode of sperm storage, may have a strong impact on the pattern of sperm usage, leading to differential male fertilization success and even varying offspring sex ratios. The female genital morphology of the linyphiid spider Pityohyphantes phrygianus was investigated, as this species was shown to possess an intriguing mechanism of sex ratio determination, possibly related to genital morphology. By means of SEM and serial semi-thin sectioning, two distinctly different spermathecae plus an additional sperm sac, equipped with several valves, were found on each side of the genital apparatus. Sperm is stored under different conditions, as one of the spermathecae exhibits large gland cells of different types that discharge their products into the spermatheca through long secretory ducts, whereas the other spermatheca is surrounded by a simpler type of gland cell. Furthermore, there are folds instead of closed ducts leading to the spermathecae, and from the spermathecae to the oviduct. The latter fertilization-fold runs inside the copulatory chamber and enters the oviduct from the outside. The mechanisms for sex ratio bias in spiders are discussed. The occurrence of two types of spermatheca of which one is twisted, provides good evidence for the involvement of female genital morphology in sex ratio control of P. phrygianus offspring. Data are compiled on species for which information is available on sex ratio and female genital morphology. We put forward a hypothesis that in species with a skewed sex ratio, there is interaction between female genital morphology and behaviour, i.e. change of body position before, during or immediately after sperm transfer.

Within the clariids (air-breathing catfish), a complete range of fusiform to anguilliform species can be observed. This study deals with the cranial morphology of Channallabes apus, an extreme anguilliform (eel-like) species, compared to the anguilliform Gymnallabes typus and the more fusiform Clarias gariepinus. The overall morphology of the head of Channallabes apus shows a hypertrophied adductor mandibulae complex, with the corresponding substantial narrowing of the neurocranium, seen in the frontals, the sphenotics, the pterotics and the posttemporo-supracleithra, as well as the reduction and displacement of the eyes and some canal bones, such as the infraorbitals and the suprapreopercles. The presence of a hypertrophied muscle complex possibly indicates that a more powerful bite may occur. This implies that adaptations can be expected in several parts of the skull. On the lower jaw of C. apus a higher coronoid process is found, and on the suspensorium, two sets of three processes are present on the hyomandibular bone, indicating a stronger connection to the neurocranium. Several of the observed features, such as the elongation of the body, the reduction of the eyes, the increase in vertebrae number, limblessness and the increasing rigidity of the skull, may also be related to a process of miniaturization.

We studied the feeding ecology of juvenile loggerhead turtles Caretta caretta in the western Mediterranean based on the contents of the digestive tract of 54 turtles (range of CCL: 34–69 cm) seized in Barcelona (Spain) in 1991. Turtles had been captured in fishing trawls, but specific information about dates and localities is not available. Despite this limitation, we obtained interesting evidences about the foraging strategies of loggerheads, with potentially important conservation implications. We report 33 new taxa in the diet. Results indicated that western Mediterranean loggerheads feed in an opportunistic way. Numerically, fish made up the most important prey group, followed by pelagic tunicates, crustaceans, molluscs and other invertebrates. The importance of fish as a food resource has been rarely reported, and several lines of evidence indicated that fish were possibly consumed as discarded by-catch. This raises the question over whether or not western Mediterranean fisheries are an important food source for juvenile loggerheads. The number and diversity of prey increased with turtle size, this may reflect the lack of prey selectivity of juvenile loggerheads coupled with a higher retention of food remains in larger turtles. Discounting prey that could be consumed as discarded by-catch, dietary data suggest that most, if not all, loggerheads of our sample were captured in neritic habitats. However, many turtles contained remains of both pelagic and benthic-demersal prey. These observations support the existence of an intermediate neritic phase in loggerheads' developmental shift from pelagic–oceanic to benthic–neritic foraging habitats, as previously suggested. During this phase, loggerheads would feed upon both pelagic and benthic prey.

By examining the morphological basis of force generation in the chelae (claws) of both molluscivorous and non-molluscivorous crabs, it is possible to understand better the difference between general crab claw design and the morphology associated with durophagy. This comparative study investigates the morphology underlying claw force production and intraspecific claw dimorphism in six brachyuran crabs: Callinectes sapidus (Portunidae), Libinia emarginata (Majidae), Ocypode quadrata (Ocypodidae), Menippe mercenaria (Xanthidae), Panopeus herbstii (Xanthidae), and P. obesus (Xanthidae). The crushers of the three molluscivorous xanthids consistently proved to be morphologically ‘strong,’ having largest mechanical advantages (MAs), mean angles of pinnation (MAPs), and physiological cross-sectional areas (PCSAs). However, some patterns of variation (e.g. low MA in C. sapidus, indistinguishable force generation potential in the xanthids) suggested that a quantitative assessment of occlusion and dentition is needed to understand fully the relationship between force generation and diet. Interspecific differences in force generation potential seemed mainly to be a function of differences in chela closer muscle cross-sectional area, due to a sixfold variation in apodeme area. Intraspecific dimorphism was generally defined by tall crushers with long in-levers, though O. quadrata exhibited an extreme dimorphism suggesting that factors unrelated to a speed–strength dichotomy (e.g. sexual selection) have shaped dimorphism of that species. It is concluded here that: (1) the majority of interspecific claw strength variation is a function of closer muscle cross-sectional area; (2) variation in claw morphology related to force production and transmission does have some relation to hardness of diet; (3) claw dimorphism in many species does seem to be related to strength and speed trade-offs; (4) factors besides molluscivory must be considered to understand claw evolution fully; (5) a quantitative assessment of force distribution, lacking in the literature, is essential for a more complete understanding of the relationship between claw design and ecological function.

The population density and nesting behaviour of gorillas (Gorilla gorilla gorilla) was studied in the Ngotto forest, Central African Republic. We carried out a nest count along 94 km of transects. Also, the herbaceous vegetation of the understory was quantified and we attempted to assess the decay rate of nest sites. A total of 145 gorilla nests in 27 nest sites was found. We found 82.1% of gorilla nests > 2 m above ground. There was a significant correlation between the height of nests and the diameter of trees with nests. The density was estimated at 0.34–0.40 weaned gorillas per km2 depending on the value of nest site decay rate used. The herbaceous vegetation was scarce in the study site (42 out of 50 quadrats had no herbaceous stems). Compared with the gorilla population of the nearby Dzanga-Sangha forest, the population density of gorillas at Ngotto was lower but the proportion of nests found above ground was much higher. These differences are discussed and we suggest that they were the result of the scarcity of herbaceous vegetation in the Ngotto forest.

Both intensity and type of habitat management in grasslands and heathlands affect spider communities. With high intensity management, spider communities often lack diversity and are dominated by a few r-selected species affiliated with bare ground. Low intensity management produces more complex communities introducing more niches for aerial web spinners and climbing spiders. The preferred management will be site-dependent and may not be appropriate for all spiders in all situations, particularly for some rare or threatened species. Providing natural cover is recommended when using extreme forms of management or intensive grazing (particularly by sheep). In extreme cases, or where trampling is heavy, the litter layer should be conserved. We advocate research and survey before and after major management implementation. Habitat management for spiders should not be considered alone, but integrated into a holistic plan. Management for spiders may conflict with rare plant conservation and small reserves should examine the viability of providing two contrasting regimes.

The crayfish Procambarus clarkii is an introduced species in Portugal, becoming a new available resource that has possibly changed local trophic relationships. The purpose of the present study was to understand better how a naïve assembly of predators reacted to a recent invader. Predation on P. clarkii by nine species of mammals (Order: Carnivora) and six species of birds (Order: Ciconiiformes) in a marsh area in Portugal, was surveyed through the collection of faeces and pellets over a 24-month period. Seasonal variation in the consumption of this prey by different predators was evaluated, and estimation made of size and weight of P. clarkii consumed by them. Procambarus clarkii was readily preyed upon by four species of mammalian carnivores and five species of ciconiiform birds. The consumption of P. clarkii varied seasonally in both years with a trend between seasonal exploitation and its population structure and availability. Generally, the use of P. clarkii by all predators was more intense in spring, summer and autumn than in winter, and was directed towards larger and heavier individuals. These findings result from the population dynamics presented by P. clarkii in the marsh area studied here, since larger and heavier individuals were more available in spring, summer and autumn. Procambarus clarkii is an important food resource for mammals and birds and it seems to play a key role in the trophic interactions of the riparian and terrestrial communities of the marsh.

Tardigrades have achieved a widespread reputation for an ability to survive more than a century in an inactive, ametabolic state called cryptobiosis. However, a closer look at the empirical evidence provides little support for the claim that tardigrades are capable of century-long survival. Instead, current evidence suggests that a decade may more realistically represent the upper limit of cryptobiotic survival in the most resistant tardigrades.

The taxonomic relationship between two toothed South African river crabs, Potamonautes warreni and P. unispinus, is unclear. The problem stems from the widespread variation in carapace dentition patterns amongst P. warreni individuals over its biogeographic range, where single toothed individuals may appear similar in carapace morphology to P. unispinus. Ten populations of P. warreni and 18 populations of P. unispinus were collected and the morphometric and genetic differentiation between the two taxa quantified. Patterns of morphometric and genetic variation were examined using multivariate statistics and protein gel electrophoresis, respectively. Principal component analyses of carapace characters showed that the two species are morphologically indistinguishable. However, discriminate functions analyses and additional statistical results corroborate the morphological distinction between the two taxa. Allozyme electrophoresis of 17 protein coding loci, indicated a close genetic similarity between the two species (I = 0.92). A fixed allelic difference at one locus (LT-2) and extensive genetic variability at another locus (PGM-1) indicate that two gene pools are present and that the two taxa are genetically isolated. Intraspecific genetic I values for both species were >0.97 and indicated no apparent genetic structuring on a micro or macro-geographic scale. The variation in carapace dentition among P. warreni populations possesses no genetic basis and may possibly be the product of ecogenesis. The value of dentition patterns in the systematics of river crabs is discussed. Dentition patterns among river crab species appear to be conserved and reliable as species specific diagnostic markers, but should ideally be used in combination with other morphological data sets and genetic evidence.

For the first time, an attempt has been made to quantify the effect of a copepod parasite (Ergasilus bengalensis) on the respiratory efficiency of the gills of a riverine catfish (Wallago attu) using an important parameter – the diffusing capacity. In addition, scanning electron microscopy has been used to demonstrate the effect of a monogeneid fluke on the gill lamellae of this catfish. The anchorage of E. bengalensis towards the leading edge of the interlamellar channels (pores) will affect laminar flow of water through the gill sieve. About 35% of the water flow (1.23×10−3 cm3/s) and lamellar area (15.41 mm2) of an infected gill filament (4.46 mm) is affected by the copepod parasite (1.59 mm). Other effects of the monogeneid flukes on the catfish included fusion of the tips of gill filaments and distortion of lamellar epithelium. Parasite-induced changes in the branchial organization are discussed in relation to oxygen uptake efficiency of the gills of the catfish.

Nicrophorine beetles (Nicrophorus and Ptomascopus spp.) use small carcasses as a food source for young, a breeding ecology distinct from other silphid beetles. While adaptations to the use of small carcasses are well known for Nicrophorus (emitting sex pheromone, burying, rounding and removing hair from carcasses, regulating brood size, regurgitating to young, and preventing predation), there is little information regarding its sister group, Ptomascopus. Like Nicrophorus, Ptomascopus morio males emit pheromone to attract females. In the absence of carrion competitors Ptomascopus morio parents were found to stay with a carcass and their brood for up to 10 days. We tested six hypotheses to examine whether young benefit from this long period of parent–offspring contact. (1) There was no evidence that parents buried or otherwise pre-empted carcasses to reduce competitive pressure. (2) We found no evidence that parents influenced the decomposition of the carcass. This was supported by experimental manipulations in which brood production (number of larvae and total brood mass) was no greater on carcasses on which parents were present than on carcasses not ‘prepared’ by parents. In addition, the carcass was not rounded and little hair was removed by the adults. (3) The presence of parents benefited the brood by reducing the negative effects of competition with carrion fly larvae. This likely resulted from predatory feeding by adult beetles. (4) Females adjusted clutch size to the size of the carcass. Parents, however, did not make a second adjustment in brood size after young reached the larval stage (filial cannibalism), as occurs in Nicrophorus. (5) Although parents were observed to open feeding holes in the carcass, this was not necessary for normal larval growth and survival. Parents were not observed to feed young directly by regurgitation. (6) Lastly, parents did not reduce predation on their brood when a conspecific intruder was present. These findings suggest that after the female parent adjusts clutch size to the size of the resource, the only parental benefit is clearing the carcass of fly larvae. Other differences with Nicrophorus include an extended period of oviposition (5 days) and less pronounced changes in ovarian mass and juvenile hormone titers in response to discovery of a carcass. In a field experiment in Kyoto, Japan, 17 of 21 broods of N. concolor during August contained larvae of P. morio. Mixed Nicrophorus–Ptomascopus broods were less common at other times of the year and when N. quadripunctatus occupied carcasses. In the laboratory, P. morio was able to parasitize 19 of 20 broods of N. concolor. The pattern of oviposition, the absence of explicit parental behaviours, and the interactions with N. concolor in the field suggest that Ptomascopus morio is a brood parasite of Nicrophorus.

We studied the effect of morphological variation and basking posture on thermal characteristics in the speckled wood butterfly Pararge aegeria (L.). The process of heating and cooling in relation to wing type (descaled, darkened and original wing colour) and size was examined using dummies (i.e. dried butterflies). Size (measured as wing length) and ambient temperature have a joint influence on body temperature: large butterflies heat up more slowly than small ones, but with increasing ambient temperature the difference with size became smaller and even changed since large individuals heated up faster under warm ambient conditions. Surprisingly, darkening wings had no overall effect on thermal characteristics, but this may be an artefact of the manipulation as supported by the results of the absorption measurements. Normal butterflies reached a higher equilibrium thoracic temperature than descaled butterflies probably because wings without scales absorb less radiation. Finally, butterflies with fully spread wings reached higher thoracic temperature and had faster cooling rates compared to butterflies with half-opened wings. Implications of the results for the relation between morphology and behaviour of speckled wood butterflies in their natural habitat are discussed.

This paper reports upon the use of nest boxes in coniferous woodland by the red squirrel Sciurus vulgaris, great tit Parus major and the jackdaw Corvus monedula over a 6-year period from 1994 to 1999. Initially 30 nest boxes were erected with eight additional boxes being put up in 1995. In the period 1994 to 1997, red squirrels were found to use nest boxes regularly as nesting and breeding sites (7.8 ± 1.0 se litters found annually). Box use was greatest in the summer and autumn months (70% of boxes being used at least once) and declined through the winter (50%) into the spring (45%). The presence of great tit clutches and broods in the spring did not prevent red squirrels from occupying boxes. Only 28% (n = 12) of all the recorded great tit clutches produced fledgling young in 1994 to 1997 and red squirrels were found to have consumed some of the chicks and eggs. The establishment of a jackdaw colony within the woodland led to 86% of the nest boxes being used by the birds in the spring of 1999. Red squirrel occupation of boxes in the spring declined to 7% and only three litters were recorded that year. The study showed that the jackdaw has the capacity to dominate nest boxes during the spring months despite the high density of red squirrels within the reserve.

The diet of the short-toed eagle (Circaetus gallicus) was studied during the breeding season by analysing pellets and remains generated by adults and nestlings. The raptor proved to be a specialist feeder, as snake prey comprised almost 95% of the diet, in both frequency and biomass. We gathered information on prey availability and prey size availability (1499 specimens of nine different species) by searching for snakes in the study area. Regressions of vertebra centrum length and dorsal-scale length on snout–vent length (SVL) of the snakes were used to calculate prey size. The taxonomic diet composition differed depending on the sample analysed – remains or pellets – but we failed to find between-year diet differences. Most of the snakes identified (140 out of 141) belonged to only three species, Malpolon monspessulanus, Elaphe scalaris, and Coluber hippocrepis. Other prey included Lacerta lepida, Natrix maura, Bufo bufo, and Alectoris rufa, and many secondary prey (prey from stomach of the prey) were also detected in the pellets. The three main prey species were consumed according to their availability in the study area, but the eagles selected on the basis of prey size. Large snakes within 700–1000 mm SVL were positively selected, whereas snakes under 600 mm SVL were negatively selected. Adult eagles consumed the same prey species as those carried to the nest to feed their single nestling, although prey given to nestlings proved larger in size and biomass, suggesting that adults consumed the smallest prey, reserving the largest for nestlings.

During reproduction, dung beetles of the genus Onthophagus typically bury portions of dung removed from the dung pad. Even though females are capable of successfully constructing and provisioning nests when unaccompanied by males, extensive levels of co-operation between sexes have been reported. In some species, males show a clear dimorphism in body plan and only large horned males are known to assist females. In O. taurus this form of paternal investment is facultative and depends on social context (namely the presence of other males). We studied relationships between body size and paternal investment in five Onthophagus species (i.e. O. coenobita, O. fracticornis, O. illyricus, O. taurus and O. vacca). Two types of tests were established. In test A, a large and a small male were placed with a single, medium-size female; in test B, a large and a small female were placed with a single large male. In controls one male was placed with one female. Individuals were maintained for 10 days. Then the enclosures were opened to assess the position of each beetle. When two mates were found in close vicinity or in the same tunnel provisioning dung, a co-operative behaviour was assumed. In competitive tests, small males and small females never co-operated with their potential mates whilst large and medium-size individuals often co-operated with mates inside the same tunnels. No differences in frequencies of co-operation were found between large and medium-size females. Small females and small males scarcely co-operated with large or medium-size mates in controls. These results suggest that large individuals outcompete the small ones. They also suggest that paternal investment depends on body size of both mates. Large males of all species assist medium-size and large females, whereas small males do not. However, large males do not invest much parental effort on small females that, in fact, are poorly assisted. We assume that large individuals of both sexes are reproductively superior to small ones. The propensity of both small females and small males to excavate was lower than that of larger individuals; accordingly, digging capacity could be a proximate factor explaining facultative paternal investment in these species.

The foraging behaviour of Brünnich's guillemots Uria lomvia was studied in a high-arctic fjord system (Kongsfjorden) in western Spitsbergen. The physical oceanographic characteristics of the water change from the head of the fjord and westward into the Greenland Sea, and are reflected in the vertical profiles of water temperatures in different parts of the area. Nine chick-rearing Brünnich's guillemots were instrumented with temperature-depth recorders, which generated vertical temperature profiles of the dives. These were compared to synoptic measurements of the water temperature characteristics of the region. This method was used to locate the foraging areas of the Brünnich's guillemots and to study the foraging site fidelity of individual birds. The results showed that only three of the nine birds foraged outside Kongsfjorden during the study period, and only 26 of the 186 dive bouts (14%) were conducted outside the fjord, 48–58 km from the colony. Most dives were probably made only a few kilometres from the colony. The data indicate that the birds showed strong fidelity to foraging areas at spatial scales of 1–20 km. However, the birds sometimes moved between feeding areas characterized by different vertical temperature profiles. The guillemots made 2229 dives during the study period and spent c. 10% of their time under water. The diving depth averaged 45 m, and the dive duration averaged 97 s. The deepest dive recorded was 136 m and lasted 196 s. We did not find any diel rhythm in the diving depths of the Brünnich's guillemots. Also, we found no diel pattern in diving frequency. These findings contradict the predominance of night-time diving observed in studies of guillemots undertaken further south.

The study focuses on the differences between large and small forms of a rotifer species, Macrotrachela quadricornifera (Rotifera, Bdelloidea), by reviewing the literature and adding further morphological differences. Evidence from life-history traits, growth patterns and trophi (hard structures of the specialized rotifer pharynx) morphology suggests that the large and small forms of M. quadricornifera should not be considered the same species. Macrotrachela vanoyei Schepens, 1954 is re-established as a good species, differing from M. quadricornifera in the smaller size of body, egg and trophi, as well as the number of proximal and distal teeth on the trophi.

Logarithmic transformation is used to transform multiplicative phenomena to a linear, additive scale. Some workers recommend the transformation x′ = log x + 1 when observed values are equal to zero. However, when working with morphometric data, this transformation is inappropriate because it arbitrarily changes the nature of the relationship between body parts. To illustrate this point, this contribution re-analyses a data set from the recent literature.