Showing papers in "Journal of Zoology in 1974"

Experiments on whether schooling by their prey affects the hunting behaviour of cephalopods and fish predators

Abstract: The experiments investigated the effects of a school of live prey fish on the hunting behaviour of squid, cuttlefish and pike (ambush predators) and perch (a chasing predator). The hunting behaviour of all species is described, including some previously unrecorded actions. For all species the increasing shoal size from one fish to six, to 20, decreased the success of the predators' attacks per encounter with a prey. This was partly because attacks on larger shoals lasted longer, and fish became increasingly difficult to catch as a hunt went on. However, for some of the species there was a clear effect of the shoals at the start of the hunt. For other species it was less conclusive. The disruptive effect of the shoals was shown to act for the ambush predators by interfering with the “optimal” sequence of an attack and causing avoidance actions together with so-called irrelevant behaviour. For the perch, shoals seemed to disrupt by forcing the predator continually to switch targets during his pursuit. The artificiality of the experiments is discussed in relation to field observations. The relatively high incidence of avoidance and irrelevant behaviour seems to be an artefact, but the main results are quite compatible with field studies. In nature fish predators may be able to get sufficient food by restricting their attacks to individuals which are conspicuous either by an abnormal appearance or by becoming separated from the school. An individual prey fish no doubt gains a considerable advantage from the school by burying itself in the crowd. Our experiments show that a shoal can provide further protection in hampering the attack of a predator.

The mechanical behaviour of some molluscan hard tissues

Abstract: Pieces of shell from 19 species of molluscs exhibiting various microstructures were tested for tensile strength, modulus of elasticity in bending and modulus of rupture. In tensile strength most shells with cross-foliated, foliated, homogeneous and crossed-lamellar structures did not exceed 60 MNm 2 but prismatic and nacreous structures often exceeded this value. Nacreous structure was generally superior to all others in modulus of rupture tests; that of Turbo being about equal to bone. Values of modulus of elasticity were more uniform between structures. There is a general relation between mechanical properties, microstructure and the life style of each animal. Nacreous structure, which is very strong but not widely used, apparently evolved earlier than the less strong but widely used crossed-lamellar structure.

The mechanics of jumping by a dog (Canis familiaris)

Abstract: A force platform has been used to obtain records of the forces exerted on the ground by an Alsatian dog, during take-off for running long jumps and standing scale jumps. The records have been analysed in conjunction with cinematograph film, taken simultaneously, and anatomical data. Stresses in the principal muscles of the hind limb, and in the triceps, have been calculated and the values obtained are compared with the stresses found by other investigators in isometric experiments with excised mammal muscles. Stresses in certain tendons and bones have been calculated, and the values obtained are compared with published values for the strength of tendon and bone. Evidence is presented that the gastrocnemius and plantaris muscles behave, in take-off for a jump, essentially as passive elastic bodies. Most of the elastic energy is probably stored in their tendons. A tendency for distal limb muscles to be pinnate, with much shorter fibres than proximal limb muscles, is noted and discussed.

Reproduction in Nephrops norvegicus (Decapoda: Nephropidae)

Abstract: During the period October 1969 to April 1972 a comprehensive study of the reproductive biology of the Norway lobster, Nephrops norvegicus (L. 1758), was made in the Irish Sea. Where possible comparison has been made with data from other areas. The results of the present investigation show that most females are berried annually, egg-laying taking place in August and September, and hatching in April to June of the following year. Moulting and copulation occur in mature females during May to August. In contrast males do not show a marked reproductive cycle, spermatogenesis occurring throughout the year. The method of fertilization is discussed, and it is suggested that this may be internal. Copulatory and egg-hatching behaviour is described, together with details of egg-laying and incubation in the laboratory. A pre-zoeal larval stage is described for the first time, bringing the total number of larval instars to four. The terminology of the larval stages is revised.

Male behaviour and territoriality in the Yellow-bellied marmot

Abstract: (With 1 plate and 8 figures in the text) Five populations of marmots were studied in Colorado from 1962 through 1972. Males are classified by age as yearlings, two-year olds, and adults. Socially, marmots are colonial, peripheral, or transient. Each population was divided into four age-sex classes, male yearlings, female yearlings, male adults, female adults, for analysis of social behaviour. Social behaviour was amicable or agonistic. Both types of behaviour occurred between male yearlings and each of the other age-sex classes. Play-fighting characterized social behaviour among male yearlings. Agonistic behaviour characterized social interactions between male yearlings and male adults. Male yearlings avoided male adults and usually dispersed from the locality. Adult male aggression enhanced but was not necessary for dispersal of yearling males. Agonistic behaviour between males and the four age-sex classes was not related to population density. Territorial males are conspicuous and advertise their presence by tail flagging. Many colonial males patrol their territory. Adult male social behaviour is predominantly agonistic. Mean rates of amicable and of agonistic behaviour between adult males and adult females were greater for years of male turnover than for years of male returns. Territoriality is characterized by exclusive use of the area by the colonial male, vigorous defence against transient or peripheral males, and by a relatively fixed area. A decrease in the number of males in an area causes an increase in the size of territories. Additional males in an area causes a decrease in the size of territories. The mean size of 24 typical territories is 0.67 ha. Reduction in the number of territories in an area was associated with increased agonistic behaviour among adult males. Fights were rare and occurred when the territorial system was unstable. The major functions of the territorial system are enhanced reproduction in a limited environment, enhanced outbreeding and enhanced fitness of colonial males.

Extraspecific imposition of social grouping among surgeonfishes (Pisces: Acanthuridae)

Abstract: The Manini is a widely distributed surgeonfish that is often abundant on reefs. It has two modes of existence, scattered individuals or dense column-forming schools, which may be seen on the same day at different places on the reef. In Hawaii schooling is a tactic used for getting to the bottom to feed when the bottom is held by territory-holding food competitors. Mixed-species “flocks” are an extension of this tactic. In atoll situations habitat partitioning exists, with the Maninis feeding in the intertidal area away from competitors; there, schooling is anti-predator behaviour.

An analysis of the contents of the anal scent pockets of Herpestes auropunctatus (Carnivora: Viverridae)

Abstract: The structure of the anal organ of Herpestes auropunctatus is described. The scent is analysed and is shown to contain a series of saturated carboxylic acids. The acids are shown to be the product of bacterial metabolism, the species involved are isolated and identified.

Field studies of the diet of Rhabdosargus holubi (Pisces: Teleostei: Sparidae)

Abstract: Rhabdosargus holubi is a marine teleost endemic to south east Africa. The juveniles occur mainly in estuaries but the adults are largely confined to the sea. Stomach contents of over 2000 juvenile R. holubi were examined from fish captured in the open Kowie and Msikaba estuaries, and from the closed West Kleinemond and Kasouga estuaries. Juvenile R. holubi feed mainly on aquatic vegetation. The fish cannot, however, digest the vegetation eaten due to the absence of a cellulase or a method of breaking up the plant tissue. Therefore, the plant material is passed out in an undigested state. Epiphytic diatoms and sessile ectoprocts (Bryozoa) are, however, removed from the macrophytes or multicellular algae in the stomach, and are subject to digestion. Diatoms may form up to 50% of the dry weight of the plants consumed. A variety of animals was also eaten. Maximum total food consumption was estimated at 1·9% of body weight per day although this is probably an underestimate. Feeding only took place during daylight hours. The teeth of juvenile R. holubi are specialized for grazing aquatic plants and differ from those of adult R. holubi. Adults consume mainly bivalves and large crustaceans. It is suggested that the different food requirements of the adults and juveniles determine at what stage this species enters and leaves estuaries.

Reproduction in male Pipistrellus pipistrellus (Mammalia: Chiroptera)

Abstract: The annual reproductive cycle has been investigated in the male pipistrelle bat Pipistrellus pipistrellus. Spermatogenesis occurs during summer and spermatozoa are produced in August and September. The seminiferous tubules then regress rapidly but sperm are stored throughout winter in the cauda epididymidis. Little change is apparent in the morphology of the Leydig cells throughout the year, and histochemical studies have revealed no seasonal differences in the occurrence of enzymes involved in steroidogenesis. The percentage yields of testosterone and androstenedione after incubation of testis and adrenal tissues in vitro with tritiated pregnenolone have been determined and measurements made of the concentration of these hormones in testes and whole blood. Although the highest levels of these androgens are synchronous with spermatogenesis, both continue to be produced by the testes during winter. Studies in castrated bats have confirmed these observations and indicate that the activity of the accessory reproductive organs during winter is dependent on testicular androgens. The testicular cycle of the pipistrelle is not thought to be complicated by adrenal androgenesis, or storage of androgens in the brown fat. The interrelationships between reproduction and hibernation in bats are discussed.

Vagility in an island population of the House mouse

Abstract: The chance of encounter—and hence mating—between two animals may be limited by social as well as spatial factors, thus dividing a population into a series of discrete territories with little movement between them. Only within the sub-units will random mating take place, and drift may cause a considerable amount of non-adaptive genetical change if the units are very small. Work on House mouse (Mus musculus) populations in the laboratory and particular ecological situations have suggested that the effective breeding size of these units may be as small as four. This would mean that a considerable amount of random change would be expected in mouse populations. However, a six year study (1964–69) of movement and territoriality on the 244 acre (100 ha) Welsh island of Skokholm during which over 3000 animals were marked and released, showed that more than 20% of individuals breed in an area other than the one in which they were born, i.e. a considerable amount of population churning takes place. This conclusion is supported by evidence of the spread of three rare biochemical variants in the population. Chance seems to play little part in the determination of the genetical constitution of the Skokholm mice. In general, estimates of the size of effective breeding units must always be qualified by an understanding of the ecology of the population in question.

The role of griffon vultures Gyps africanus and Gyps ruppellii as scavengers

Abstract: In the Serengeti, predator kills formed from 8 to 45 % of the carcasses that griffon vultures fed upon, the remaining carcasses coming from animals that had died from other causes. But since vultures obtained only very small amounts of food from predator kills, they had to rely for their food supply chiefly on the carcasses that were derived from other causes. In the Serengeti the large proportion of migratory ungulates prevent the mammalian predators from building up to a population size that can be responsible for a large proportion of ungulate mortality. It is estimated that the mammalian predators only take about one quarter of the potential food supply available for carnivores. The remaining ungulates die from various other causes, and so provide food for scavengers which varies in abundance and location with the seasons. This is a food supply which mammalian scavengers cannot easily use but griffon vultures, with their adaptations for gliding flight, are able to exploit it. These vultures therefore exploit a basically different food supply from predators and probably evolved as scavengers of migratory ungulate populations.

Aposematic and cryptic Lepidoptera tested on the mouse

Abstract: The toxicity of 53 species of Lepidoptera which are aposematic (a) at all stages of development; (b) as larvae but not as adults; (c) as adults but not as larvae, is compared with that of cryptic species, by means of a qualitative test consisting of intraperitoneal injection into the laboratory mouse. Points of interest which emerged from this study include (i) Pieris brassicae is toxic whether or not the larval diet contains sinigrin and mustard oils; (ii) a marked sexual dimorphism in toxicity is noted in several species; (iii) a yellow (recessive) variety of Callimorpha dominula (ab. lutea) is less toxic than the typical form; (iv) P. brassicae pupae are acceptable to certain birds if the larvae are reared on artificial diet, but rejected (on account of taste or smell) if fed on cabbage; (v) only Arctia caja, out of 14 species tested, retains its toxicity when dried, and (vi) the gravid female Zygaena trifolii and her eggs kill the mouse in two to three minutes.

Respiratory surface areas of an air‐breathing siluroid fish Saccobranchus (Heteropneustes) fossilis in relation to body size

Abstract: The surface area of the gills, air sacs and skin have been measured in specimens of different body size and their relationship to body weight fits the equation: area=aWb. The slopes (b) of the double logarithmic plots are 0.746 (gills), 0.662 (air sacs) and 0.684 (skin). The gills are poorly developed and their average weight specific area is less than figures obtained for sluggish marine fishes. The skin has an area about 70% of the total respiratory surfaces (gills+air sac+skin). Nevertheless the greater thickness of the skin leads to a smaller diffusing capacity of the tissue barrier (Dt) as compared with the gills and air sac. The air sac area for each ml of air that it contains is about 10.5 cm2 which is much lower than figures obtained for lungs of other air-breathing fish and for tetrapods.

Reproduction and “March madness” in the Brown hare, Lepus europaeus

Abstract: The reproductive physiology of hares was studied in 760 animals shot throughout the year, and these observations were related to seasonal changes of behaviour in an attempt to explain the significance of “March madness”. The hare was found to have a prolonged breeding season; at least some pregnant females were found in all months from January to August, and fertile males in all months except October and November. The nadir of the reproductive cycle occurred in October with no breeding amongst the females, and the males showing regressed accessory glands and involuted testes containing minimal amounts of testosterone. At this time hares were solitary and it was rare to see them active during the day. After the autumn rest period, the first indication of a new reproductive cycle occurred in November with an increase in the size and activity of the testes. This trend continued during December, January and February by which time the reproductive tract was again fully functional. During this time there were striking changes in behaviour and matings were witnessed. Females resumed breeding in January with a marked synchrony in the timing of the first ovulation of the season. Mating preceded ovulation, and the first pregnancy normally resulted in a single fetus, although pregnancy failure was common at this time. By March and April the hares showed full reproductive activity with 100% of females pregnant and most carrying three or more fetuses. Many aspects of behaviour (March madness) reached a peak at this time, and in males this was closely related to a depletion of sperm reserves in the epididymis and the secretions of the accessory gland reservoir. During May, June and July, the females continued to be highly fertile. There was, however, already a reduction in the overt behaviour characteristic of spring, and there was a conspicuous drop in testicular testosterone production. The reproductive cycle ended in July and August with a reversal of the changes seen earlier in the year. The testes regressed rapidly in August and sperm production ceased by September; the sperm reserves in the epididymis became progressively depleted and sperm were degenerating by October. There was a reduction in litter size towards the end of the breeding season and no pregnancies were observed after the end of August. Of the hares under one year old shot in the spring only about 16% were apparently conceived during the period of spring madness, with the majority arising from matings in May, June and July. The age at puberty was influenced by the date of birth. March madness appears to represent the rutting behaviour of male hares and is induced by the greatly increased testosterone production which occurs in spring. The behaviour is probably important in stimulating the females into breeding activity at the beginning of the new season.

Species variations in the foetal growth rates of eutherian mammals

Abstract: While the larger cetaceans have the greatest known specific foetal growth rates (Huggett & Widdas, 1951), examination has shown that among land mammals of a particular Order, Sub-order or even Genus, there may be marked variation in rates.

Development and morphology of the glochidium larva of Anodonta cygnea (Mollusca: Bivalvia)

Abstract: The development of the parasitic glochidium larva of Anodonta cygnea L. is outlined, with reference to earlier studies on unionid larvae, and a comparison is made between the mature glochidia of the three genera, Anodonta, Unio, and Margaritifera. The glochidium of Anodonta cygnea is anatomically and morphologically specialized in connection with its parasitic existence. The specialized structures are described, and their significance discussed.

Carotenoids in thirty‐eight species of Lepidoptera

Abstract: Carotenoids in 38 species of Lepidoptera have been examined qualitatively and quantitatively. Comparisons are made between cryptic and aposematic species, pupae and adult, dried and fresh material, males and females, and certain polymorphic species. Although some selective storage is demonstrated, Lepidoptera chiefly store the carotenoids present in their food plants unchanged. It was found that the Large White (Pieris brassicae), a toxic species, stored more carotenoids than the less toxic Small White (P. rapae) while ab. coerulea (P. brassicae) contained only 25 % of the carotenoids found in typical specimens.

Osmotic properties of the perivitelline fluid and some properties of the chorion of Atlantic salmon eggs (Salmo salar)

Abstract: The chorion and perivitelline fluid of Atlantic salmon eggs were investigated by chemical and physical methods. The turgor pressure of the chorion in water hardened eggs was about 60 mm Hg. With newly stripped eggs in fresh water a similar pressure was achieved after about one day but the process of water uptake could be osmotically inhibited by adding high molecular weight substances to the external medium. Perivitelline fluid contained about 58 % water the remainder being a high molecular weight substance consisting mainly of protein but also containing significant quantities of carbohydrate and lipid. The functions of the chorion are discussed with reference to salmon eggs and also to marine pelagic fish eggs such as those of the plaice.

Reproduction in the Malayan freshwater cerithiacean gastropod Melanoides tuberculata

Abstract: Melanoides tuberculata in the Kuala Lumpur area of Malaysia were found to be entirely female, reproducing parthenogenetically. The reproductive system is extremely simple in structure and histology, lacking all the glandular developments common in most mesogastropods. Eggs pass into a cephalic brood-pouch where they develop to juveniles of 5–6 shell whorls before emergence. Numbers of developing young in the brood-pouches increased with shell height of the parents except for a decline in the few very largest snails. The highest brood-pouch count was 265, but average counts were much lower. 85 % of developing young in the brood-pouches were very early stages from eggs to embryos of one whorl only, perhaps implying that many eggs fail to develop successfully to young snails. Three localities studied yielded consistently different brood-pouch counts, implying variation in fecundity. Juveniles emerge from the brood-pouch most commonly between nightfall and midnight and normal emergence seems to require diurnal alternation of light and dark. In continuous darkness, brood-pouch counts increased markedly, perhaps as a result of greater activity and feeding during darkness. Several features of the reproductive biology suggest that Melanoides might become a useful experimental animal in freshwater studies.

The nerves in frog skin

Abstract: In the epidermis of frog skin, most nerves are situated at the top of the basal layer. More superficial nerve fibres are usually adjacent to flask cells; it is concluded that this is not a functional association, but a consequence of the pattern of moulting. There are nerve fibres in the walls of the granular glands; mucous glands appear to have no intrinsic innervation although nerves pass within a short distance of their walls. The smooth muscle bundles of the dermis are innervated, and have a physical attachment to the overlying epidermis.

Observations on the ecology and breeding biology of the genus Chiromantis (Amphibia: Rhacophoridae)

Abstract: The construction of foam nests by the Anura seems to be a habit that has evolved separately in all the main zoogeographical regions. Chiromantis is a large tree frog weighing up to 5.5 g which is restricted to the Ethiopian region. This genus comprises three species which are found in the three main African biomes from rain forest (C. rufescens), through woodland (C. xerampelina) to semi-arid savannah (C. petersii). The female of C. rufescens is shown in this study to construct her nest with the assistance of three males, and like the other two species, the nests are always fastened to objects over temporary water sources. Although the rain forest and savannah species are the same size the latter lays twice as many eggs as the former. Additionally it is shown that the eggs of C. petersii are only half the size of C. rufescens. These facts can be correlated with the degree of permanence of the water source over which the nest is constructed. Features of the water economy and ecology are also described.

On the spatial distribution, feeding and reproduction of the vermetid gastropod Dendropoma maximum

Abstract: D. maximum is a dominant species of outer reef flats in the Red Sea, reaching densities of about 22/m2 and biomass of 15.8 g dry tissue/m2. A few individuals attached to loose rocks are found inside the breaker zone but they may have been dislodged by heavy seas from the outer reef flat. D. maximum feeds from a mucus net which is spread by wave action over the substratum. Hauling the net occurs at approximately 13 minute intervals throughout the 24 hours and lasts about two minutes. Neighbours with overlapping nets stimulate each other to haul and reduce feeding efficiency. The net is grasped by a pair of lateral jaws, tugged free of the substratum by rotation of the body and ingested by a zipper-like action of the lateral and marginal radula teeth. The robust, central and lateral teeth become worn, possibly while channelling out the substratum to accommodate new shell. Defaecation occurs about 2.4 times an hour, amounting to 10450 kcal/m2/y. Females may brood simultaneously at least 11 egg capsules at various stages of development, which are suspended by stalks from the roof of the shell and pass through a dorsal slit in the mantle. Each capsule contains–500 embryos which develop into larvae with simple, coiled shells 0.33 mm in diameter. There is no planktonic phase. Adult shells amount to 2.5 kg/m2 on the outer reef flat, while dead shells are often occupied by blennies. Although D. maximum is not a specialized filter feeder, the highly developed ciliary mechanisms suggest that filtering may be an auxiliary feeding method.

Experiments on resting site selection by nocturnal moths

Abstract: When different species of moths are presented with a choice between black and white resting backgrounds, there is a strong correlation between the colour selected and the reflectance of the forewings. Under more natural conditions, light-coloured moths usually rest on fresh vegetation whilst dark-winged species select tree bark or rest upon the ground, and different defensive strategies appear to have been adopted by species in these two latter situations. Studies on the mechanism of background selection, and on background selection in polymorphic species, are reviewed.

A multidisciplinary approach to a new species of Gobius (Teleostei: Gobiidea) from southern Cornwall

Abstract: The Mediterranean-Atlantic genus Gobius L. (type G. niger L.) is redefined with listing and comparison of the 14 species currently assigned to it. A G. auratus complex of species is discussed with special reference to the real identity of the former species originated by Risso. Features of a further new species, Gobius couchi, from Helford, Cornwall, and Lough Ine, Co. Cork, are compared with those of its nearest relatives, G. auratus Risso, 1810, G. luteus Kolombatovic, 1891, and another new offshore form from the English Channel. A systematic description of G. couchi is given, including details of head lateral-line canals and sensory papillae, and also of the karyotype (Appendix). A summary of biology covers geographical distribution, habitat and associated intertidal fishes, diet, parasites, reproduction, age-composition, and size. The electrophoretic properties of selected functional proteins (haemoglobins, muscle-myogens, and lactate-dehydrogenase isozymes) are described and contrasted with those in other available neighbouring species (G. paganellus, G. niger, and Thorogobius ephippiatus). Alternative terminology for LDH patterns is discussed, and the role of protein studies considered for gobioid classification. The specific status of G. couchi relative to the Mediterranean G. auratus is reviewed, and meristic divergence between the two compared with that found among widely separated populations of G. niger which exhibit less geographical variation in these criteria. Mechanisms for allopatric speciation are discussed, and it is concluded that ancestral populations of the two forms became parted possibly at the time of the Roman regression (corresponding to the Mindel glaciation) when the Mediterranean may have been closed-off from the Atlantic. Rates of evolution shown by European gobiids are considered in the light of Pleistocene and postglacial opportunities for reproductive isolation.

A re‐examination of the subspecies of Red deer (Cervus elaphus) with particular reference to the stocks in Britain

Abstract: In 1906, Lonnberg identified a native subspecies of Red deer Cervus elaphus scoticus L., in Britain after examining a sample of stags' skulls from Glenquoich (Inverness-shire, Scotland). In north-west England, it is commonly believed that “Red deer of indigenous stock have persisted in this area (Furness Fells, Lancashire, England) from time immemorial…” (Chard, 1966). Arrangements were made to introduce animals into a park within this area in 1970, which, in view of this local opinion, would have been the only Red deer within the district not of native origin. Therefore, it was thought desirable to examine all the stocks of wild or feral Red deer in Britain and to determine which, if any, of them could be considered native and thus deserving of special measures to ensure their survival. After examining samples of skulls, using multivariate analysis, it appeared that, within the limits of the material representing the various subspecies of the world, there was little support for the concept of subspeciation in Red deer. In Great Britain, however, there appeared to be two distinct forms of Red deer leading a free existence, one presumed to be native and the other to be of park derivation. Visually, the differences were indetectable and could be demonstrated only by discriminant analyses.

Structure and keratinization of the skin of a fresh-water teleost Notopterus notopterus (Notopteridae, Pisces)*

Abstract: The microanatomy of the skin of an air-breathing fish, Notopterus notopterus is described and related to the distribution of various histochemical constituents involved in keratinization. In addition to distinct unicellular mucous glands, secreting sulphated acid mucopolysaccharides, the epidermis of TV. notopterus is mainly composed of polygonal cells containing sulphated acid mucopolysaccharides, concentrated in the distal peripheral areas of the cells. The mucopolysaccharide contents of these polygonal cells gradually increase as they mature and move towards the outer surface. They may ultimately form a part of the protective keratinized layer. The mature keratinized cells give positive reactions with Papanicolaou's stain, contain cystine bound SS groups, cysteine bound SH groups, calcium and moderate amounts of sulphated acid mucopolysaccharides. These cells having flat pyknotic nuclei undergoing karyolysis, are fused together at their lateral margins to form an intact sheet which is frequently seen sloughing off from the underlying epidermal cells. The process of cornification in N. notopterus is comparable to that of the amphibians and the aquatic reptile–the turtle. There exists a well developed lymphatic system in between the cells of the stratum germinativum having lymphatic spaces often penetrating deep into the middle layer. This is an adaptation which contributes largely to the protective function of the fish skin. The layers between the scales and the basement membrane contain sulphated acid mucopolysaccharides. This together with keratinization has been correlated with the peculiar mode of life of the fish, often facing the problems of desiccation. The epidermis is anchored on the dermis by fine strands of collagen fibres connecting the basement membrane and the scales, and by numerous fine papilla-like projections of the basement membrane projecting in between the cells of the stratum germinativum. Numerous fine elastic fibres in the connective tissue pockets in which scales are lodged, provide for free movement of the scales when the body of the fish is bent during swimming. Pit organs singly or in groups are found distributed in the epidermis.

Effects of group stability, male‐male aggression, and male courtship behaviour on environmentally‐induced ovarian recrudescence in the lizard Anolis carolinensis

Abstract: Reproductively inactive, winter dormant female Anolis carolinensis were exposed to a stimulatory environmental regime while in socially stable or unstable male-female groups. In a second experiment, winter dormant females were exposed to varying amounts of male courtship and male-male aggression. Results indicate that (1) the presence of a stable dominance hierarchy among group males is necessary for male facilitation of environmentally-induced ovarian recrudescence (OR) (an unstable dominance hierarchy inhibits OR), (2) the behaviour patterns responsible for the facilitation and inhibition of environmentally-induced OR are courtship and male-male aggression, respectively, and (3) ovarian development is graded in accordance to the amount of male courtship to which the female is exposed. It is proposed that male courtship insures normal gonadotropin (GT) secretion while the absence of male courtship results in subnormal GT secretion and the presence of male-male aggression suppresses environmentally-induced GT secretions. The functional significance of the inhibition of environmentally-induced OR by male-male aggression and its possible relation to differential vernal emergence in temperate-zone reptiles is discussed.

Protozoan parasites of the blood of British wild birds and mammals

Abstract: The reported occurrence of protozoan parasites of the blood of British wild birds and mammals is reviewed. Nineteen species of British birds have been recorded as hosts of Haemoproteus (or Parahaemoproteus), Leucocytozoon (or Akiba), Plasmodium, Trypanosoma or “atoxoplasms” (a group whose taxonomic status is presently in doubt), and seventeen species of British mammals are known to be hosts of Babesia, Hepatozoon, Polychromophilus or Trypanosoma (including at least three species from Chiroptera: T. (Schizotrypanum) dionisii, T. (S.) vespertilionis and T. (Megatrypanum) incertum).

Storage lipids in the lizard Lacerta vivipara: a quantitative study

Abstract: Lipids in various tissues of Lacerta vivipara were measured at three times of the year: immediately after hibernation, mid-season, and immediately prior to hibernation. Lipid deposits in the abdominal fat bodies and the caudal fat bands fluctuated seasonally, but at any time showed a marked positive allometry with body length and weight; the functional significance of this relationship is not known. Carcass lipid and liver weight were isometric with body length and weight.