Visual fields and eye movements in a harbor seal (Phoca vitulina)
نویسندگان
چکیده
The boundaries of the visual fields of a harbor seal were measured using static perimetry. In the seal lying on a plane surface (fixation point "0 degrees" straight ahead at eye-level), the visual field with fixed eyes extended over 208 degrees horizontally and reached from -12 degrees to +69 degrees vertically. The binocular visual field amounted to 67 degrees. Eye movements of 12 degrees (+/-2) degrees to both sides and 64 degrees upwards could be induced. In the seal performing eye movements, a visual field of 210 degrees in the horizontal plane and 121 degrees to the dorsal side was determined. From the measured eye movements, a visual field of 232 degrees in the horizontal plane appears possible.
منابع مشابه
Optokinetic nystagmus in harbor seals (Phoca vitulina)
Harbor seals experience motion due to self-motion and to movement in the external world. However, motion vision has not been studied yet in marine mammals moving in the underwater world. To open up this research, optokinetic nystagmus (OKN) as a basic motion sensing and retinal image stabilizing reflex was studied in four harbor seals during stimulation with moving black-and-white stripe patter...
متن کاملDolphin morbillivirus infection in a captive harbor seal (Phoca vitulina).
During the second morbillivirus epidemic (2007 to 2011) in cetaceans along the Italian coastline, dolphin morbillivirus (DMV) was detected by molecular analyses in a captive harbor seal (Phoca vitulina), with pathological findings consistent with morbillivirus infection. This report confirms interspecies DMV transmission from cetaceans to pinnipeds.
متن کاملGenome Sequence of Streptococcus phocae subsp. phocae Strain ATCC 51973T Isolated from a Harbor Seal (Phoca vitulina)
Streptococcus phocae subsp. phocae is a pathogen that affects different pinniped and mammalian species. This announcement reports the genome sequence of the type strain ATCC 51973 isolated in Norway from clinical specimens of harbor seal (Phoca vitulina), revealing interesting genes related to possible virulence factors.
متن کاملSeroprevalence of Toxoplasma gondii in North-eastern Atlantic harbor seal (Phoca vitulina vitulina) and grey seal (Halichoerus grypus).
Antibodies to Toxoplasma gondii were determined in serum samples from 47 grey seals (Halichoerus grypus) and 56 harbor seals (Phoca vitulina vitulina) from the Atlantic coasts of United Kingdom and France. Antibodies to T. gondii assayed by the modified agglutination test (MAT) were found in 14 (13.6%; IC(95%): 7.0-20.2) of 103 seals tested, with titres of 1:25 in 13 seals and 1:50 in 1 seal. S...
متن کاملBrightness discrimination in the harbor seal (Phoca vitulina)
The brightness discrimination ability of a male harbor seal was investigated at an ambient illumination of 0.9lx. The visual stimuli consisted of circular gray discs that were presented on a black background on a TFT monitor. Eight standard intensities were tested against sets of lower comparison intensities. In accordance with Weber's law we observed a constant gain of the just noticeable inte...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
عنوان ژورنال:
- Vision Research
دوره 46 شماره
صفحات -
تاریخ انتشار 2006