摘要:

AbtractThe pygmy sperm whale (Kogia breviceps) and the bottlenose dolphin (Tursiops truncatus) are equipped with a tapetum fibrosum and, with other Cetacea, are the only carnivores known to possess this typically ungulate tapetal type. Tapeta from two regions of a retina, each with a different spectral reflectance (blue and green), were found to have significantly different fibrillar diameters and inter‐fibrillar spacing. When the measured values are applied to a dielectric reflector model, the predicted wavelengths agree with the observed reflectance of the flat‐mounted tapeta. The spatial properties of the fibrils change progressively from the tapetal origin in the fibroblast layer to the pigment epithelium, suggesting that different wavelengths may be reflected systematically with tapetal depth. The very large number of reflecting layers characterizing these tapeta, relative to those of other carnivores, may provide for increased spectral purity and efficie

ISSN:0824-0469    

DOI:10.1111/j.1748-7692.1988.tb00537.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractHistologic studies of pancreatic tissues of one pygmy sperm whale,Kiogia breviceps, and one dwarf sperm whale,K. simus, demonstrated rather typical exocrine pancreatic anatomy. Peroxidase‐antiperoxidase (PAP) techniques determined that the cell composition of the islets of Langerhans resembled that of other mammals. Within islets, cells secreting insulin (B‐cells) and glucagon (A‐cells), were clearly demonstrated, but, surprisingly, isolated A‐ and B‐cells were also found among pancreatic acinar cells. PAP techniques demonstrated the presence of neuron‐specific enolase within islets, but failed to provide a sufficiently clear reaction to demonstrate the presence of somarostatin‐producing D‐cells. No positive PAP reaction for ser

ISSN:0824-0469    

DOI:10.1111/j.1748-7692.1988.tb00538.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractSurvival rates for three species of captive cetaceans are reported, based on records of dates of capture, birth, and death of individual animals. The annual survival rate was 0.93 for bottlenose dolphins and killer whales and 0.94 for white whales. Confidence limits of these estimates are discussed. Differences in survival rates between institutions were significant for bottlenose dolphins only. Calf survival for bottlenose dolphins was lower than non‐calf survival. Survivorship of male killer whales was significantly less than survivorship of female killer whales; sex‐specific survival rates were similar for the other two species. Estimates of average or maximum longevity alone were not useful in comparing rates of survival. Because survival in the first year of captivity may be lower than subsequent years, estimates of the expected lifespan, based on data from the first few years of captivity, may be bia

ISSN:0824-0469    

DOI:10.1111/j.1748-7692.1988.tb00539.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractThe bony falx (BF) and bony tentorium (BT) of spotted dolphins (Stenella attenuata) at different growth stages were observed. The BF and BT were observed to have the shape of the entire falx cerebri (FC) and tentorium cerebelli (TC), respectively, in adults, but were not seen in fetuses at all. Partially formed BF and BT were observed in the young. The BF and BT of spotted dolphins are formed by ossification in the FC and TC in the course of aging. Based on age determination by means of dentinal growth layers of the maxillary teeth, the ossification in the FC and TC of spotted dolphins begins by about 1 yr of age, and is completed, except for the passage of nerves and blood vessels, by about 9 yr of age. The BF and BT of spotted dolphins are formed possibly by continual dietary intake of large amounts of calcium, phosphorus and vitamin D.

ISSN:0824-0469    

DOI:10.1111/j.1748-7692.1988.tb00540.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractFour aerial survey projects were conducted between 1977 and 1986 to determine the abundance, density and distribution of West Indian manatees (Trichechus manatus), in the northern Banana River, Kennedy Space Center, Florida. Manatee density and distribution within selected portions of the 78.5 km2study area were determined. Peak numbers of manatees occurred in spring of each year. The maximum counts increased from 56 in 1978 to 297 in 1986. Manatee abundance was lowest in the winter of each year. Mean density per flight increased from 0.52 manatees/km2 in 1977–78 to 2.73/km2in 1984–86. This increase may reflect increases in the east coast population or shifts in the population distribution. Distributional changes were observed in the study area through time, with a lower percentage of manatees occurring in industrial areas and a correspondingly higher percentage of manatees in nonindustrial areas by 1

ISSN:0824-0469    

DOI:10.1111/j.1748-7692.1988.tb00541.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractMilk samples from the stomachs of harp seal pups were analysed for Cu, Zn, Se, Cd and Hg, as were liver, kidney, and muscle from mother‐pup pairs. Tissues were also analysed for MeHg. Milk contained, in addition to essential trace metals, Cd and Hg (57 ng/g and 6.5 ng/g respectively).Pups had mercury in all three tissues. The percent methyl mercury in liver of pups was higher than in liver of mothers. Mercury in muscle was mostly methyl mercury in both mothers and pups. Total mercury in liver of mothers but not pups was correlated positively with selenium. Estimates of ingested mercury by pups indicated they had acquired most of their mercury during gestation.Although mothers had cadmium in liver and kidney, it was not detected in tissues of pups. Cadmium did not transfer across the placenta, while mercury did. Tissue concentrations of Cu and Zn were higher in pups than mothers. The presence of metallothionein in pup tissues was postulated.A strong positive correlation of copper and selenium between mothers and pups indicated transfer of these elements from mother to pup in direct proportion to their concentrations in maternal liver and kidne

ISSN:0824-0469    

DOI:10.1111/j.1748-7692.1988.tb00542.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

ISSN:0824-0469    

DOI:10.1111/j.1748-7692.1988.tb00543.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Book reviewed in this article:TheCommunityEcology ofSeaOtters. EcologicalStudies65. G. R. Van Blaricom and J. A. Estes, eds.

ISSN:0824-0469    

DOI:10.1111/j.1748-7692.1988.tb00544.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

ISSN:0824-0469    

DOI:10.1111/j.1748-7692.1988.tb00545.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY