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  • 2000-2004  (2)
  • 1990-1994  (3)
  • 1
    Digitale Medien
    Digitale Medien
    The biology of the finetooth shark,Carcharhinus isodon (1993)
    Springer
    Environmental biology of fishes 36 (1993), S. 219-232 
    Details
    ISSN: 1573-5133
    Schlagwort(e): Range ; Nurseries ; Fertilization ; Migrations ; Feeding ; Elasmobranchs
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Synopsis The finetooth shark inhabits shallow coastal waters of the western Atlantic from North Carolina to Brazil. It is common off the southeastern United States, where it spends the summer off Georgia and the Carolinas and winters off Florida. The species appears in the nursery and mating areas of South Carolina when the surface water temperature rises above 20° C in late April and early May. Both adults and juveniles are common in the shallow coastal waters of South Carolina through the summer, where they feed primarily on menhaden. The finetooth shark leaves the Carolinas in early fall and migrates southward as the surface water temperature decreases below 20° C. Females reach maturity at about 1350 mm TL. Males mature at about 1300 mm TL. The finetooth shark has consecutive, year-long ovarian and gestation cycles, like most carcharhinid sharks. Mating occurs from early May to early June. Freshly mated females bear a large spermozeugma at the base of each uterus. The spermozeugmata are large almond shaped masses of individual spermatozoa embedded in a supporting matrix. Embryos are lecithotrophic during their first fifteen weeks of development. Subsequently, the embryos establish a placental connection to the mother. Implantation occurs when the embryos measure about 130 mm or at about the fifteenth week of gestation. Gravid females carrying young 480–550 mm TL enter the shallow water nurseries off South Carolina in late May. Parturition occurs from late May to mid-June, after a gestation period of about twelve months, plus or minus two weeks. The young measure 480–580 mm TL at birth. Oocytes grow little during the gestation cycle. After parturition, a cohort of oocytes begins to develop, that will be ovulated the following May. Thus, the ovarian cycle lasts about a year, although most of the oocyte growth occurs in the months just prior to ovulation.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00001717
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  • 2
    Digitale Medien
    Digitale Medien
    The shark nursery of Bulls Bay, South Carolina, with a review of the shark nurseries of the southeastern coast of the United States (1993)
    Springer
    Environmental biology of fishes 38 (1993), S. 37-48 
    Details
    ISSN: 1573-5133
    Schlagwort(e): Migrations ; Parturition ; Habitat ; Elasmobranchs ; Neonates
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Synopsis Shark nurseries, or nursery areas, are geographically discrete parts of a species range where the gravid females of most species of coastal sharks deliver their young or deposit their eggs, and where their young spend their first weeks, months, or years. These areas are usually located in shallow, energy rich coastal areas where the young find abundant food and have little predation by larger sharks. Nurseries are characterized by the presence of both gravid females and free swimming neonates. Neonates are young bearing fresh, unhealed umbilical scars in the case of placental species, or those at or near the birth size in aplacental species. Bulls Bay, South Carolina, is a nursery for the blacknose, spinner, finetooth, blacktip, sandbar, dusky, Atlantic sharpnose, scalloped hammerhead, and smooth dogfish sharks. The lemon shark has its nursery in shallow waters of south Florida and the Bahamas. The bull shark has its nursery in the lagoons of the east coast of central Florida.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00842902
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  • 3
    Digitale Medien
    Digitale Medien
    The Biology of the Nurse Shark, Ginglymostoma cirratum, Off the Florida East Coast and the Bahama Islands (2000)
    Springer
    Environmental biology of fishes 58 (2000), S. 1-22 
    Details
    ISSN: 1573-5133
    Schlagwort(e): elasmobranch ; name ; maximum size ; size at maturity ; reproduction ; reproductive cycle ; gestation ; lecithotrophy ; brood size ; diet
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The nurse shark is an extremely abundant shallow water species in Florida and the Caribbean, yet its biology is poorly known. Moreover, there is a great deal of misinformation about it in the literature. The maximum size and weight attained by the nurse shark have often been exaggerated. None of the specimens measured in this study exceeded 265 cm TL and 114.5 kg, and none of the specimens actually measured by other researchers exceeded 280 cm. Females reach maturity at a length of 223–231 cm, or at 86% of their maximum size. Males reach maturity between 214 and 214.6 cm in length or at about 83% of their maximum size. Mating primarily occurs from mid-June to early July. The embryos are enclosed in sturdy egg capsules for the first 12–14 weeks of gestation. In a gravid female, the embryos are at different stages of development during the first four months of gestation. Embryos are lecithotrophic and there is no evidence of any supplemental mode of embryonic nourishment. Embryos measure 28–30.5 cm at birth. The gestation period is estimated at about five to six months. Brood sizes are large, ranging from 21 to 50 young, with a median of 34 young. The reproductive cycle of the nurse shark consists of a five to six-month gestation period and a two-year ovarian cycle. Thus, the reproductive cycle is biennial and a female produces a brood every two years. The nurse shark is an opportunistic predator that consumes a wide range of small fishes, primarily grunts (Haemulidae).
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1007698017645
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  • 4
    Digitale Medien
    Digitale Medien
    Description of a Juvenile Megamouth Shark, Megachasma pelagios, Caught off Brazil (2000)
    Springer
    Environmental biology of fishes 59 (2000), S. 117-123 
    Details
    ISSN: 1573-5133
    Schlagwort(e): Chondrichthyes ; Megachasmidae ; elasmobranch ; new record ; Atlantic ; morphometrics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract A juvenile male megamouth shark was caught by a commercial longline vessel off Brazil. This specimen is the only juvenile megamouth examined and the only one from the Atlantic Ocean. Megamouth shark is one of the rarest sharks in the world. Only 14 specimens have been reported since its description in 1983 by Taylor et al. All previous specimens examined have been adults from the Pacific and Indian Oceans. It appears that the species is cosmopolitan.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1007609617773
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  • 5
    Digitale Medien
    Digitale Medien
    Reproduction, placentation, and embryonic development of the Atlantic sharpnose shark, Rhizoprionodon terraenovae (1993)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 218 (1993), S. 257-280 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The Atlantic sharpnose shark Rhizoprionodon terraenovae (Richardson) is a small carcharhinid that is a common year-round resident along the southeast coast of the United States. It is viviparous and its embryos develop an epithelio-vitelline placenta. Females enter shallow water to give birth in late May and early June. Mating occurs shortly after parturition, and four to seven eggs are ovulated. Fertilized eggs attain the blastoderm stage in early June to early July. Separate compartments for each egg are formed in the uterus when the embryos reach 3-30 mm. Embryos depend on yolk for the first 8 weeks of development. When embryos reach 72 mm their yolk supply is nearly depleted and they shift to matrotrophic nutrition. When the embryos reach 40-55 mm, placental development begins with the vascularization of the yolk sac where it contacts the uterine wall. Implantation occurs at an age of 8-10 weeks by which time the embryos reach 70-85 mm. The expanding yolk sac engulfs the maternal placental villi, and its surface interdigitates with the villi to form the placenta. The rest of the lumenal surface of the uterus is covered by non-placental villi that appear shortly after implantation. Histotrophe production by the non-placental villi begins just after their formation. The placenta grows continuously during gestation. The egg envelope is present throughout gestation, separating maternal and fetal tissues. Embryos develop numerous appendiculae on the umbilical cord. Young sharks are born at 290-320 mm after a gestation period of 11 to 12 months. © 1993 Wiley-Liss, Inc.
    Zusätzliches Material: 15 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1052180304
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