Avian pox infection, aspergillosis and renal trematodiasis in a Royal tern

Poxvirus infection and aspergillosis were diagnosed in a Royal tern (Thalasseus maximus) based on gross and microscopic lesions. This represents the first known report of avian pox in a tern. Renal trematodiasis, caused by a species of Renicola also is described.     

Rostral pores in turtles

Rostral pores are epidermal invaginations which occur on the internarial region of most chelonians. Representatives of all Recent chelonian families and 67 of the 74 extant genera were examined grossly and/or histologically. Pores are absent only in the families Carettochelyidae, Cheloniidae, and Dermochelyidae. The number and microscopic structure of pores vary markedly within and between taxa. Morphological data suggest that rostral pores could function in mechanoreception. The possible origin and evolution of rostral pores are discussed in the context of other chelonian integumentary speializations.     

Metabolic scaling in turtles

Bennett and Dawson (1976) presented an analysis of the relationship of metabolic rate (MR) and body mass among turtles, based on 10 studies, but unlike most of other groups of ectotherms, there has been no update to include the many later reports on turtles. Here I present a review of the data on turtle metabolic rates at 20, 25, and 30 °C, along with regression equations and graphical analyses from a large number of studies. Two generalities emerge: (1) reported metabolic rates for sea turtles are higher than for other chelonians, although it is not certain whether this is an intrinsic characteristic of sea turtles or an artifact related to experimental conditions (such as greater activity of sea turtles in metabolic chambers and the fact that a number of studies were done with the turtles out of water), and (2) the slopes of the log–log plots of metabolic rate (MR) vs. body mass [b in the allometric equation MR = a(mass)^b] are mostly lower than previously reported in smaller studies.     

Tegmento-thalamic relations in turtles

A focus of evoked potentials and the largest number of spike responses of single units to tegmental stimulation were found in immobilized turtles (Emys orbicularis), lightly anesthetized with chloralose, in the ventral region of the thalamus, which is a heterosensory zone of predominantly somatosensory modality. Incomplete separation of lateral- and medial-tegmental projections between the dorsal and ventral portions of the ventral thalamic region respectively was discovered. Tegmental stimulation, coinciding with or preceding electrodermal or photic stimulation, causes predominant depression of somatic single unit responses, but has less effect on visual responses. The possibility of comparison of tegmento-thalamic systems in reptiles and mammals is discussed.I. M. Sechenov Institute of Evolutionary Physiology and Biochemistry, Academy of Sciences of the USSR, Leningrad. Translated from Neirofiziologiya, Vol. 12, No. 2, pp. 165–174, March–April, 1980.     

Tegmento-telencephalic relations in turtles

Electrophysiological characteristics of tegmental projections in the forebrain were studied in immobilized turtles (Emys orbicularis), anesthetized with chloralose. The main zone of representation of the tegmentum is located in the striatum, where evoked responses with shorter latencies were recorded and a larger number of units responding distinctly to tegmental stimulation was concentrated than in the dorsal ventricular ridge and general cortex. At the striatal level predominance of lateral tegmental projections was found in the lateral zone and of medial tegmental projections in the medial zone of the striatum. An inhibitory action of conditioning stimulation of the tegmentum on somatic evoked potentials and single unit responses was established. An attempt was made to compare the tegmento-telencephalic system in reptiles and mammals.I. M. Sechenov Institute of Evolutionary Physiology and Biochemistry, Academy of Sciences of the USSR, Leningrad. Translated from Neirofiziologiya, Vol. 12, No. 3, pp. 255–263, May–June, 1980.     

Hatching behavior in turtles

Incubation temperature plays a prominent role in shaping the phenotypes and fitness of embryos, including affecting developmental rates. In many taxa, including turtles, eggs are deposited in layers such that thermal gradients alter developmental rates within a nest. Despite this thermal effect, a nascent body of experimental work on environmentally cued hatching in turtles has revealed unexpected synchronicity in hatching behavior. This review discusses environmental cues for hatching, physiological mechanisms behind synchronous hatching, proximate and ultimate causes for this behavior, and future directions for research. Four freshwater turtle species have been investigated experimentally, with hatching in each species elicited by different environmental cues and responding via various physiological mechanisms. Hatching of groups of eggs in turtles apparently involves some level of embryo-embryo communication and thus is not a purely passive activity. Although turtles are not icons of complex social behavior, life-history theory predicts that the group environment of the nest can drive the evolution of environmentally cued hatching.     

Respiration in neonate sea turtles

The pattern and control of respiration is virtually unknown in hatchling sea turtles. Using incubator-raised turtles, we measured oxygen consumption, frequency, tidal volume, and minute volume for leatherback (Dermochelys coriacea) and olive ridley (Lepidochelys olivacea) turtle hatchlings for the first six days after pipping. In addition, we tested the hatchlings' response to hypercapnic, hyperoxic, and hypoxic challenges over this time period. Hatchling sea turtles generally showed resting ventilation characteristics that are similar to those of adults: a single breath followed by a long respiratory pause, slow frequency, and high metabolic rate. With hypercapnic challenge, both species responded primarily by elevating respiratory frequency via a decrease in the non-ventilatory period. Leatherback resting tidal volume increased with age but otherwise, neither species' resting respiratory pattern nor response to gas challenge changed significantly over the first few days after hatching. At the time of nest emergence, sea turtles have achieved a respiratory pattern that is similar to that of actively diving adults.     

Food-borne trematodiasis: current chemotherapy and advances with artemisinins and synthetic trioxolanes

Over 40 million people are infected with food-borne trematodes and 750 million are at risk of food-borne trematodiasis, and yet this tropical disease is neglected. The current arsenal for the treatment and control of food-borne trematodiasis comprises praziquantel and triclabendazole, which were developed 20-30 years ago. The safety, therapeutic profiles and concern about resistance of these two drugs are summarized here. Recent advances with the artemisinins, which are best known for their antimalarial and antischistosomal properties, and the synthetic trioxolanes in different trematode-rodent models are reviewed. Lastly, prospects for the development of a safe, efficacious, inexpensive and broad-spectrum trematocidal drug are considered.     

Hemoprotozoa of freshwater turtles in Queensland

Blood smears from 27 turtles (15 Emydura signata, nine Elseya latisternum, and three Chelodina longicollis) from southeastern Queensland (Australia) were examined for infections by hemoprotozoan parasites between January and June 1999. Infections were found in 26 (96%) of the turtles. Twenty five (93%) were infected with the adeleorin coccidian Haemogregarina clelandi, eight (30%) with the hemosporidian Haemoproteus chelodinae, 11 (41%) with the kinetoplastid flagellate Trypanosoma chelodinae, and eight (30%) with a novel Trypanosoma sp. Despite the high prevalence and intensity of infections, there was no evidence of clinical disease in any of the turtles.     

Evolution of bite performance in turtles

Abstract Among vertebrates, there is often a tight correlation between variation in cranial morphology and diet. Yet, the relationships between morphological characteristics and feeding performance are usually only inferred from biomechanical models. Here, we empirically test whether differences in body dimensions are correlated with bite performance and trophic ecology for a large number of turtle species. A comparative phylogenetic analysis indicates that turtles with carnivorous and durophagous diets are capable of biting harder than species with other diets. This pattern is consistent with the hypothesis that an evolutionary increase in bite performance has allowed certain turtles to consume harder or larger prey. Changes in carapace length tend to be associated with proportional changes in linear head dimensions (no shape change). However, maximum bite force tends to change in proportion to length cubed, rather than length squared, implying that changes in body size are associated with changes in the design of the jaw apparatus. After the effect of body size is accounted for in the analysis, only changes in head height are significantly correlated with changes in bite force. Additionally, our data suggest that the ability to bite hard might trade off with the ability to feed on fast agile prey. Rather than being the direct result of conflicting biomechanical or physiological demands for force and speed, this trade‐off may be mediated through the constraints imposed by the need to retract the head into the shell for defensive purposes.     

Fishhook lesions in loggerhead sea turtles

This study describes four cases of loggerhead sea turtles with fishhooks in the gastrointestinal tract. Two dead turtles with a hook in the esophagus had local fibrosis with an invagination of the keratinized stratified squamous epithelium surrounding the hook, isolating it from the subjacent stroma, one had a hook in the cloaca which was expelled spontaneously, and one had plication of the intestine with necrosis caused by the long monofilament line attached to the hook lodged in the esophagus. Lethal injuries were related to the effect of strangulation and traction produced by the line throughout the gastrointestinal tract rather than the presence of the hook in the esophageal mucosa. Hook size, point of attachment to the gastrointestinal tract, the presence or not of a long monofilament line, and the traction applied by it could be crucial for turtle survival.     

Biphasal long-distance migration in green turtles

Sea turtles have recently been shown to have the sensory ability to use magnetic information for guidance in the open ocean, although the importance of different potential navigational cues remains unknown. Between May and August 2001, we satellite-tracked green turtles, Cheloniamydas, during their >2000-km postnesting migration from Ascension Island to Brazil, following five individuals both during their transoceanic crossing and while on the Brazilian coast. None of the turtles travelled directly to its final destination but, instead, there were extended (up to 792 km) movements along the coast after the oceanic crossings. The extent of movement along the coast was unrelated to the oceanic crossing route. For example, individuals whose final destination was in the north of Brazil did not follow a more northerly oceanic crossing than those with a more southerly final destination. These observations show that green turtles returning from Ascension Island do not swim directly to their final destination, but instead conduct migration in two distinct phases: a fairly direct open ocean crossing, following which they turn north or south along the coast to reach their final destination. This long-distance migration may therefore be conducted without turtles needing to resort to sophisticated navigational skills. These previously unidentified long coastal movements may heighten the risk of turtles being captured by fishermen. Copyright 2002 The Association for the Study of Animal Behaviour. Published by Elsevier Science Ltd. All rights reserved.     

Variation in reproductive output of marine turtles

Most marine turtle species are non-annual breeders and show variation in both the number of eggs laid per clutch and the number of clutches laid in a season. Large levels of inter-annual variation in the number of nesting females have been well documented in green turtle nesting populations and may be linked to environmental conditions. Other species of marine turtle exhibit less variation in nesting numbers. This inter-specific difference is thought to be linked to trophic status. To examine whether individual reproductive output is more variable in the herbivorous green turtle (Chelonia mydas Linneaeus 1758) than the carnivorous loggerhead (Caretta caretta Linneaeus 1758), we examined the nesting of both species in Cyprus over nine seasons. Green turtles showed slower annual growth rates (0.11 cm year⁻¹ curved carapace length (CCL) and 0.27 cm year⁻¹ curved carapace width (CCW)) than loggerhead turtles (0.36 cm year⁻¹ CCL, 0.51 cm year⁻¹ CCW). CCL was highly correlated to mean clutch size in both green (R²=0.51) and loggerhead turtles (R²=0.61) and maximal clutch size of green turtles (R²=0.58). Larger females did not lay a greater number of clutches or have a shorter remigration interval than smaller females of either species. On average, the size of green turtle clutches increased and that of loggerhead turtles decreased as the season progressed. Individual green turtles, however, produced more eggs per clutch through the season to a maximum in the third or fourth clutch. In loggerhead turtles, clutches 1-4 were very similar in size but the fifth clutch was 38% smaller than the first. No individuals of either species were recorded laying more than five clutches. Green turtles may not be able to achieve their maximum reproductive output with respect to clutch size throughout the season, whereas only loggerhead turtles laying five clutches (n=5) appear to become resource depleted. Green turtles nesting in years when large numbers of nests were recorded laid a greater number of clutches than females nesting in years with lower levels of nesting.     

Physiological ecology of overwintering in hatchling turtles

Temperate species of turtles hatch from eggs in late summer. The hatchlings of some species leave their natal nest to hibernate elsewhere on land or under water, whereas others usually remain inside the nest until spring; thus, post-hatching behavior strongly influences the hibernation ecology and physiology of this age class. Little is known about the habitats of and environmental conditions affecting aquatic hibernators, although laboratory studies suggest that chronically hypoxic sites are inhospitable to hatchlings. Field biologists have long been intrigued by the environmental conditions survived by hatchlings using terrestrial hibernacula, especially nests that ultimately serve as winter refugia. Hatchlings are unable to feed, although as metabolism is greatly reduced in hibernation, they are not at risk of starvation. Dehydration and injury from cold are more formidable challenges. Differential tolerances to these stressors may explain variation in hatchling overwintering habits among turtle taxa. Much study has been devoted to the cold-hardiness adaptations exhibited by terrestrial hibernators. All tolerate a degree of chilling, but survival of frost exposure depends on either freeze avoidance through supercooling or freeze tolerance. Freeze avoidance is promoted by behavioral, anatomical, and physiological features that minimize risk of inoculation by ice and ice-nucleating agents. Freeze tolerance is promoted by a complex suite of molecular, biochemical, and physiological responses enabling certain organisms to survive the freezing and thawing of extracellular fluids. Some species apparently can switch between freeze avoidance or freeze tolerance, the mode utilized in a particular instance of chilling depending on prevailing physiological and environmental conditions.     

中国海龟标志方法纵览

广东惠东港口海龟湾是我国目前唯一的海龟国家级自然保护区,在1985—2005年的21年间,共保护绿海龟安全上岸产卵1184头次,标志放流成年雌海龟125头,近几年又开展了海龟卫星追踪试验,并获得了丰富的研究数据。海龟个体标志为开展科学研究活动提供了极大的方便,有利于建立龟口管理档案,完善海龟标识溯源信息系统。有关海龟生物学生态学的许多问题,例如母龟每季产卵次数、巢间期、产后洄游路线、母龟生殖周期、每一族群产卵地和觅食地分布。