Carettochelys Research Articles

Beach Selection in Nesting Pig-Nosed Turtles, Carettochelys insculpta

We investigated beach selection of nesting Pig-Nosed Turtles (Carettochelys insculpta) along a 63-km stretch of river for two years. We found 221 nests on 82 nesting beaches and identified 171 potential nesting beaches based on previously published criteria. Beaches with nests had a greater substrate moisture content and corresponding higher cohesive sand line (hereafter CSL) than beaches without nests. Beaches with nests also had a higher CSL than beaches with only crawls. Beach temperatures increased with a seasonal increase in air temperatures and were influenced by aspect and total angle of solar exposure. Turtles did not select beaches that were hotter or cooler, on average, than what was available, indicating that turtles were not manipulating offspring sex through choice of nesting beach.

Sex Differences in Activity and Movements in the Pig-Nosed Turtle, Carettochelys insculpta, in the Wet-Dry Tropics of Australia

Abstract Dry season movement patterns, home ranges, and activity was studied in a population of pig-nosed turtles (Carettochelys insculpta) in the wet-dry tropics of northern Australia. Compared to other turtles inhabiting lotic habitats, C. insculpta occupied considerably larger home ranges, covering up to 10 km of river. Of previously published factors influencing home range size, low productivity of the (micro) habitat may best explain the extensive home ranges in C. insculpta. Patchiness and low nutrient value of the chief food (aquatic vegetation) of C. insculpta may force turtles to cover large expanses of river to acquire sufficient energy for growth and reproduction. Females were more active, moved farther, and occupied larger home ranges than males. Home ranges of females comprised 1–4 activity centers, many of which were associated with thermal springs. We suggest that females may exhibit increased activity and movements relative to males because of sexual inequality in parental investment, wher...

Embryonic aestivation and emergence behaviour in the pig-nosed turtle, Carettochelys insculpta

Two related aspects of hatchling emergence were studied in a population of pig-nosed turtles (Carettochelys insculpta) in northern Australia. Using emergence phenology data, nest temperatures, historical weather data, and a developmental model, we tested the hypothesis that delayed hatching occurs in C. insculpta, and that such a delay would allow hatchlings to time their emergence to match the onset of the wet season. Carettochelys insculpta hatchlings emerged, on average, 17 days after dates predicted from a developmental model. Combined with observations of hatchlings remaining in eggs until emergence, these results confirmed delayed hatching in nature. This delay was synchronized with initial river rises associated with the onset of wet-season rains, and is consistent with published criteria for embryonic aestivation. On a diel scale, we generated predictions of two potentially competing models of nocturnal emergence in hatchling turtles based on the knowledge that air temperatures decrease with season during the emergence period. A test of these predictions for C. insculpta produced ambiguous results. However, further analysis indicated that C. insculpta, and probably other nocturnally emerging turtle species, respond to a decline in diel temperature rather than to an absolute temperature. The former would ensure nocturnal emergence, while the latter is experienced during the day as well as at night. Nocturnal emergence may be associated with nesting in open microhabitats.

Embryonic aestivation and emergence behaviour in the pig-nosed turtle, Carettochelys insculpta

Embryonic aestivation and emergence behaviour in the pig-nosed turtle, <i>Carettochelys insculpta</i>

Ageing the eggs and embryos of the pig-nosed turtle, Carettochelys insculpta (Chelonia: Carettochelydidae), from northern Australia

Standard series of embryonic stages are the primary basis for organising information in embryological studies and for ageing eggs and embryos in field studies. In this paper we calibrate the developmental series for the pig-nosed turtle, Carettochelys insculpta, from northern Australia against an established series for Chelydra serpentina, carefully noting unique attributes of C. insculpta. We also extend existing non-destructive approaches to staging embryos by identifying several additional specific embryological attributes visible externally or by candling. A chronological sequence of attributes visible by candling is established as a viable alternative to the destructive approaches requiring direct examination of embryos.

Ageing the eggs and embryos of the pig-nosed turtle, &lt;i&gt;Carettochelys insculpta&lt;/i&gt; (Chelonia: Carettochelydidae), from northern Australia

Ageing the eggs and embryos of the pig-nosed turtle, &lt;i&gt;Carettochelys insculpta&lt;/i&gt; (Chelonia: Carettochelydidae), from northern Australia

Trade-offs between Reproductive Traits and the Influence of Food Intake during Pregnancy in the Garter Snake, Thamnophis elegans

Trade-offs between Reproductive Traits and the Influence of Food Intake during Pregnancy in the Garter Snake, Thamnophis elegans

Some observations on the Pig-nosed Turtle (Carettochelys insculpta) in northern Australia

Some observations on the Pig-nosed Turtle (Carettochelys insculpta) in northern Australia

Dry-Season Distribution and Ecology of Carettochelys-Insculpta (Chelonia, Carettochelydidae) in Kakadu-National-Park, Northern Australia

Carettochelys insculpta is widely distributed (though not necessarily abundant) in Kakadu National Park during the dry season, occupying permanent billabongs from the black-soil plains to the base of the escarpment. High population densities were found in the upper reaches of the South Alligator drainage (33.8 turtles ha-1; 227.4 kg ha-1) and are interpreted as dry-season concentrations of turtles that would occupy a much wider range in the wet season. C. insculpta nest in clean, fine sand adjacent to water from mid July to early November. About 15 hard-shelled spherical eggs were laid in a shallow chamber (maximum depth 18-21 cm) between 1.0 and 3.7 m from water, with the height above water ranging from 0.4 to 0.7 m. The nests suffered heavy predation from varanid lizards. The turtles are general omnivores that draw upon a wide variety of food, including algae, aquatic macrophytes, fruits, seeds and leaves of riparian vegetation, aquatic macroinvertebrates, and carrion. Its catholic tastes provide great scope for opportunism, and its diet varies greatly in accordance with the foods available from locality to locality. The ecological basis for the restricted global distribution of C. insculpta is unclear since the species appears to have very broad habitat requirements.

Paradeuterobaris novaguineae n. gen. and n. sp. (Digenea: Microscaphidiidae) from the Intestine of Carettochelys insculpta (Reptilia: Chelonia) from Papua New Guinea

Paradeuterobaris n. gen. is erected for Paradeuterobaris novaguineae from the small intestine of Carettochelys insculpta Ramsay, 1886, from the Kikori River, Papua New Guinea. The new genus is placed in the Deuterobaridinae Looss, 1902, which is emended to include it. Paradeuterobaris differs from other genera in the subfamily (Deuterobaris Looss, 1900, and Neodeuterobaris Brooks, 1976) in the number of rows of ventral glands, its lack of both a dorsal cephalic lobe and of oral diverticula, the position of the ovary with respect to the ends of the ceca, and distribution of vitellaria. Paradeuterobaris novaguineae is the first parasite recorded from Carettochelys insculpta.

The Enigmatic Plateless River Turtle, Carettochelys, in Serological Survey

Precipitation patterns in agar-double-diffusion plates have suggested taxonomic dis- tinctness of Carettochelys. Lissemys (of the Cyclanorbinae) was found to be distinct from Caret- tochelys rather than intermediate between Carettochelys and the Trionychinae. In decreasing order of reactions from Carettochelys are members of the Trionychidae: Pelochelys, Trionyx and Lisse- mys; Kinosterninae; Cheloniidae; Platysternon; Batagurinae and Emydinae (Emys orbicularis strongest); Testudininae; Chelidae; and Pelomedusa. The New Guinea plateless river tur- tle, Carettochelys insculpta, now found in lowland waters of southern Papua, New Guinea, and northern Australia, lives mostly in fresh but also in salt water (Schultze-Westrum, 1963). It has flip- pers somewhat resembling those of sea turtles, symmetrically-arranged bony plates as in the Testudinidae, and a leathery plastron and carapace covering along with a fleshy proboscis resem- bling that of the Trionychidae. The two- clawed flippers are much broader than those of sea turtles, and skin of Caret- tochelys does not protrude beyond the osseous carapace as is characteristic of the Trionychidae. Because of its simi- larities to several groups coupled with its unique features, Carettochelys has been termed a living missing among turtles. This strange animal was descriued by Ramsay (1886) who placed it near Tri- onyx and considered it a link between river and sea turtles. Boulenger (1889) classified Carettochelys in its own mono- typic family (a rank generally accepted today) and he listed it as one of three pleurodire families (along with Pelo- medusidae and Chelidae). The trend has been to exclude Carettochelys from close association with pleurodires, but Bou- lenger (1889) was followed by Gadow (1901) who listed it among pleurodires; Deraniyagala (1939) indicated like pref- erence saying that externally it showed convergence to Trionychidae. How- ever, Baur (1891) showed that it is not a pleurodire, and he noted resem- blances to Trionychidae as well as to Dermatemys, Staurotypus and other kino- sternines. Waite (1905-1907) comment- ed that:

Comparative Chondro-Osseous Development and Growth of Marine Turtles

Longitudinal skeletal growth in appendicular long bones of Caretta caretta resembles the patterns in Pseudemys scripta and Carettochelys insculpta. A metaphyseal cone of cartilage becomes transiently isolated through the formation of a subphyseal plate of calcified cartilage which undergoes early peripheral vascular irruption and ossification. The noncalcified epiphyseal cartilage remains thin and avascular. Skeletal growth in Dermochelys coriacea is remarkably divergent from other living chelonians. Primary vascular irruption occurs into the noncalcified hypertrophied cartilage of the metaphysis with rapid extension of vascularity also into the non-hypertrophied epiphyseal cartilage. Endochondral ossification of the metaphysis advances contiguously from the diaphysis, a subphyseal calcified cartilage plate does not form, and there is no isolation of a metaphyseal cartilage cone. The noncalcified epiphyseal cartilage remains thick with transphyseal as well as perichondral vascularization through cartilage canals. The pattern in Dermochelys may be due to very rapid skeletal growth to a large body size. The giant Cretaceous Archelon ischyros has a similar skeletal vascular pattern, whereas the giant Tertiary Stupendemys geographicus resembles normal chelonians. In many respects, skeletal growth of Dermochelys resembles marine mammalian patterns.

Karyotypes and evolutionary relationships of trionychoid turtles.

Standard karyotypes of carettochelyid and trionychid turtles are similar. The pitted-shelled turtle, Carettochelys insculpta (2n=68), and three species of softshelled turtles, Trionyx spiniferus, T. ferox and T. sinensis (2n=66) were examined. Chromosomal banding patterns are the same among the species of Trionyx studied, but substantially different from non-trionychoid turtles. Karyotypic similarity supports previous morphological studies that indicate the families Carettochelyidae and Trionychidae are closely related or that both families are distantly related to other turtles.

The Pitted Shelled Turtle Carettochelys insculpta in the Northern Territory

The Pitted Shelled Turtle Carettochelys insculpta in the Northern Territory