932 resultados para turtle shell
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A large population of the giant Amazon river turtle (Podocnemis expansa) nests along the beaches of the Crixás-Açu River in the central western region of Brazil. In spite of the existence of several point bars in the area, only a selected group of beaches is used for nesting by P. expansa. Geological aspects, such as river width and depth, beach height above 200 cm with sandy sediments, were indispensable for the choice of these nesting sites. The relatively reduced dimensions of the point bars and the great number of turtles, which nest in the same local, contributed to the existence of a high nest concentration. The rapid rise of the Crixás-Açu River caused the flooding of the beaches and the drowning of hatchlings and embryos. It is estimated that nearly all the nests were lost. The height of the nesting place and the time of flooding related to the incubation period are decisive in embryo survivorship. The Retiro, Júnior, Assombrado and Limoeiro beaches, which are situated at heights of 183 to 310 cm, were inundated on 8 November 2000. The Barreira Branca beach, with a height of up to 380 cm was completely inundated on 13 December 2000. All of these beaches were flooded before the hatchlings emerged.
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The aim of this paper is to compare three different methods for counting white blood cells [WBC] (Natt and Herrick method, estimation with 1,000 and 2,000 erythrocytes) and three methods for counting total thrombocytes [TT] (Wojtaszek method, estimation with 1,000 and 2,000 erythrocytes) in a South American freshwater turtle species, Podocnemis expansa, Schweigger 1812 (Reptilia, Pelomedusidae). Direct WBC counts using the Natt and Herrick method showed limitations, which are discussed here. The WBC and TT counts using 1,000 erythrocytes from blood smears are not recommended for Amazon turtles nor other reptilian species, since wide variation in counts can be observed. Estimation methods for determining WBC and TT based on 2,000 erythrocytes of blood smears were most acceptable because they allow a differentiation between leukocytes and thrombocytes and also had a smaller variation. The methods investigated here for the Amazon turtle, which have been widely used in other reptile species, provided evidence that the most acceptable method is not that of using diluted stains and a hemocytometer.
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The Cutia-nut (Couepia edulis Prance), a species originally from the Amazon region, has a kernel with reasonable nutritional value and a hard and thick woody shell that constitute most of the fruit. After the kernel removal, the shells are regarded as waste. The possibility of using such shells, as raw material for burning or charcoal production, as well as milled residue for structural reinforcement materials is quite feasible, considering environmental and economical aspects. There is, however, a complete lack of characterization of the Cutia-nut shell and other similar species which can aggregate desirable qualities for application as engineering material. In this study some analyses are presented aiming at providing information for potential uses of these residues. In general, the shells follow a regular shape with certain dimensional proportionality to the kernel. The shell is a fibrous material with high lignin content, present low water absorption and high resistance to natural degradation.
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The biology and ecology of South American turtles is still poorly known, particularly, for the Brazilian species. Laboratory studies are essential to understand the life cycles of aquatic turtles species and to help in formulating management plans for their conservation. As a contribution to the knowledge of Podocnemis erythrocephala species, we give a description of its species-typical behaviors, categorized as: maintenance, locomotion, feeding, agonistic and reproduction, based on captives observations of four pairs of turtles in an aquarium in Manaus, Brazil. Similarities and differences with the repertoires of other turtle species are discussed, concluding that turtles have much more complex adaptative strategies and social life than was believed.
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Predation and alteration of microhabitats may represent high risk for nesting of Amazonian turtles. This study aimed at investigating the nesting and body parameters of neonates of Podocnemis unifilis in the Araguari River basin, State of Amapá, Brazil. The spawning sites of this turtle were monitored along the Falsino River (a region with two reserves) and in the urban area of the Porto Grande city along the Araguari River, from August to December 2011. A total of 180 nests were found and the nesting occurred from September to November, with prevalence in October. Eggs hatching occurred in December. The mean incubation period was 63.5 ± 5.2 days and the eggs hatching success was 25%. However, approximately 80% of the nests had suffered predation mainly by humans, which occurred in both the protected areas of the reserves and the urban area. The pattern of nesting site choice was discussed. Egg size was larger than that previously described for the same turtle species in the other regions. The body condition index of neonates indicated a good use of vitelline reserves. The results indicate the urgent need for strategic actions to conserve and maintain the natural stocks of this relatively vulnerable turtle in the region.
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Magdeburg, Univ., Fak. für Naturwiss., Diss., 2010
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[s.c.]
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no.23(1926)
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The plastral spotting variation in the chelid turtle Phrynops hilarii (Duméril & Bibron, 1835) in relation to sex, size, and geographic procedence of individuals was analyzed. States for qualitative characters were analyzed using non-parametric tests. Quantitative characters (shell and scute measurements) were standardized for body size by linear regression against carapace length, and were subjected to principal components analysis and canonical discriminant function analysis. Results suggest that increased plastral spotting is a polymorphic ontogenetic trait in P. hilarii. Neither hatchlings nor juveniles have plastral pattern moderately or heavily pigmented. The simplest pattern, however, may persist without changes in some adults. There are no differences between sexes. The spatial distribution of the plastral pattern is not ordered latitudinally or longitudinally, showing no relationship with gradients of elevation, temperature, or precipitation. This pattern trait lacks of taxonomic significance. The morphometric analysis failed to reveal any character of diagnostic utility in the plastron to support the possibility that these patterns correspond to different sympatric taxa.
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v.34:no.41(1956)
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v.31:no.13(1947)
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Shell selection by the hermit crab Paguristes tortugae Schmitt, 1933 from Anchieta Island (Brazil) was analyzed using the six most frequently occupied shell species in the field and taking into account the sexual condition of the individuals, the shell size and the shell species. The experiments were conducted under laboratory conditions and the shell species preference was estimated on the basis of the frequency that each species was chosen by the individuals. The preferred shell species and size were determined by regression analysis. The highest correlation coefficients were obtained for the relations between the hermit dimensions and shell dry weight. The ovigerous females preferred shells with larger internal volume: Leucozonia nassa (Gmelin, 1791) and Cerithium atratum (Born, 1778). In the experiment of shell size, males preferred heavier shells whereas females selected the shape characteristics of the shell, such as the aperture and the internal volume, which are probably related to the growth and offspring guarantee, respectively. In general, and independent of sex condition, P. tortugae showed significant selection among all shells utilized. The results suggest that shell selection by P. tortugae involves sexual and reproductive condition preferences.
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We evaluated the gastropod shell utilization pattern of the hermit crab Clibanarius vittatus (Bosc, 1802) at Pescadores Beach in São Vicente, State of São Paulo, Brazil. Specimens were collected monthly from May 2001 through April 2003, in the intertidal zone at low tide. The crabs were weighed and their carapace shield length measured. All gastropod shells were identified and had their shell biometric parameters (total length and aperture length) measured (mm) and weighed (g). A total of 2,344 hermit crabs (644 males, 1,594 females, 45 ovigerous females and 61 individuals in intersex), using 13 species of gastropod shells, were collected. Stramonita haemastoma (Linnaeus, 1767), Cymatium parthenopeum (Von Salis, 1793) and Achatina fulica (Bowdich, 1822) comprised over 98% of all the shells. Male and intersex crabs were significantly larger than the females. This size difference strongly influenced the shell utilization pattern, principally in A. fulica, which has the largest shell size, that was only used by males and intersexual individuals of C. vittatus. Cymatium parthenopeum was the only shell species that showed a high determinant coefficient in all the biometric correlations evaluated. The high abundance of S. haemastoma shells and a strong correlation between crab size and shell aperture length established by a significant determination coefficient, indicated that C. vittatus uses this species as the principal resource for shell occupation at Pescadores Beach.
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v.37:no.12(1955)