Morphological changes during the embryonic development of limbs of the green turtle,Chelonia mydas,were studied during the entire period of incubation,using transmission and scanning electron microscopy(TEM and SEM). ...Morphological changes during the embryonic development of limbs of the green turtle,Chelonia mydas,were studied during the entire period of incubation,using transmission and scanning electron microscopy(TEM and SEM). Limb buds were first observed at Stage 2. At that stage,the tip was covered with an apical ectodermal ridge(AER) which began to regress at Stage 6. Associated with AER was the presence of the mesenchymal cells which,consequently,differentiated into muscles,cartilage and bones. The gross features of the skeletal development appeared as a condensation of the cartilaginous structures in the proximal distal region of the limbs. The primordial digits were gradually enclosed by hard keratinized webbed skin. The increase in rate of ossification and skin pigmentation was correlated with the growth of the limbs. The development of the limbs was closely related to the transitional appearance of mucus secretion from the epidermis.展开更多
During the period August 17-28, 2001, in collaboration with the Provincial Bureau of Oceanography & Fisheries of Guangdong and the South China Institute for Endangered Species, the South China Sea Institute of Oce...During the period August 17-28, 2001, in collaboration with the Provincial Bureau of Oceanography & Fisheries of Guangdong and the South China Institute for Endangered Species, the South China Sea Institute of Oceanology, a CAS affiliate in the city of Guangzhou, conducted a sea turtle satellite tracking project at Haigui Bay (Fig. 1) in the vicinity of Gangkou Town, Huidong County, Guangdong Province.展开更多
Using satellite transmitters,we determined the internesting movements,spatial ecology and diving behavior of East Pacific green turtles(Chelonia mydas)nesting on Nombre de Jesús and Zapotillal beaches along the P...Using satellite transmitters,we determined the internesting movements,spatial ecology and diving behavior of East Pacific green turtles(Chelonia mydas)nesting on Nombre de Jesús and Zapotillal beaches along the Pacific coast of northwestern Costa Rica.Kernel density analysis indicated that turtles spent most of their time in a particularly small area in the vicinity of the nesting beaches(50%utilization distribution was an area of 3 km^(2)).Minimum daily distance traveled during a 12 day internesting period was 4.6±3.5 km.Dives were short and primarily occupied the upper 10 m of the water column.Turtles spent most of their time resting at the surface and conducting U-dives(ranging from 60 to 81%of the total tracking time involved in those activities).Turtles showed a strong diel pattern,U-dives mainly took place during the day and turtles spent a large amount of time resting at the surface at night.The lack of long-distance movements demonstrated that this area was heavily utilized by turtles during the nesting season and,therefore,was a crucial location for conservation of this highly endangered green turtle population.The unique behavior of these turtles in resting at the surface at night might make them particularly vulnerable to fishing activities near the nesting beaches.展开更多
文摘Morphological changes during the embryonic development of limbs of the green turtle,Chelonia mydas,were studied during the entire period of incubation,using transmission and scanning electron microscopy(TEM and SEM). Limb buds were first observed at Stage 2. At that stage,the tip was covered with an apical ectodermal ridge(AER) which began to regress at Stage 6. Associated with AER was the presence of the mesenchymal cells which,consequently,differentiated into muscles,cartilage and bones. The gross features of the skeletal development appeared as a condensation of the cartilaginous structures in the proximal distal region of the limbs. The primordial digits were gradually enclosed by hard keratinized webbed skin. The increase in rate of ossification and skin pigmentation was correlated with the growth of the limbs. The development of the limbs was closely related to the transitional appearance of mucus secretion from the epidermis.
基金The test is a research project supported by the CAS sponsored Knowl-edge Innovation Program and Guangdong Province s Bureau of Ocean-ography&Fisheries.Its participants also include Liu Yun,a graduate student at the South China Sea Institute of Oceanology,Chan Kinfung of the Hong Kong Agriculture,Fisheries&Conservation Department,and senior engineer Gu Hexiang of the Haigui Bay Nature Reserve.
文摘During the period August 17-28, 2001, in collaboration with the Provincial Bureau of Oceanography & Fisheries of Guangdong and the South China Institute for Endangered Species, the South China Sea Institute of Oceanology, a CAS affiliate in the city of Guangzhou, conducted a sea turtle satellite tracking project at Haigui Bay (Fig. 1) in the vicinity of Gangkou Town, Huidong County, Guangdong Province.
基金funded by the L.D.Betz Chair of Environmental Science endowment of Drexel Universitythe Leatherback Trust.
文摘Using satellite transmitters,we determined the internesting movements,spatial ecology and diving behavior of East Pacific green turtles(Chelonia mydas)nesting on Nombre de Jesús and Zapotillal beaches along the Pacific coast of northwestern Costa Rica.Kernel density analysis indicated that turtles spent most of their time in a particularly small area in the vicinity of the nesting beaches(50%utilization distribution was an area of 3 km^(2)).Minimum daily distance traveled during a 12 day internesting period was 4.6±3.5 km.Dives were short and primarily occupied the upper 10 m of the water column.Turtles spent most of their time resting at the surface and conducting U-dives(ranging from 60 to 81%of the total tracking time involved in those activities).Turtles showed a strong diel pattern,U-dives mainly took place during the day and turtles spent a large amount of time resting at the surface at night.The lack of long-distance movements demonstrated that this area was heavily utilized by turtles during the nesting season and,therefore,was a crucial location for conservation of this highly endangered green turtle population.The unique behavior of these turtles in resting at the surface at night might make them particularly vulnerable to fishing activities near the nesting beaches.
