The eyes of harp seals are large and prominent, enabling them to see well in the dim light underwater. In the bright glare on the ice, their pupils contract to a vertical slit, allowing them to see comfortably there too.
Savukārt ledus žilbinošajā spožumā acu zīlītes saraujas šaurā spraudziņā, tāpēc arī šis spilgtais apgaismojums netraucē roņiem lieliski pārredzēt apkārtni.