Generally, the eyes of nocturnal animals —like small cats— have multifocal lenses that allows them to increase contrast and depth of field in low light conditions. A circular pupil, contracting to protect the eye against bright light, would interfere with this type of structure (the iris shades the peripheral zones of the lens) leading to the loss of well-focused images. The slit pupils, therefore, may have developed in association with multifocal optical systems because more effective.
Vice versa, big cats are generally diurnal predators and they have monofocal eyes like us. So, their pupils tend to be circular because they are an adequate adaptation to monofocal optical systems.
Biological Pacemaker Cells Reset Heartbeats
Genetically tweaking heart tissue to regulate the speed of heartbeats could one day be an alternative to electronic pacemakers, a new study reports.
Read more about this research from the 16 July issue of Science Translational Medicine here.
[Video © AAAS/Carla Schaffer.]
Snow doughnuts might look like carefully constructed ice sculptures, but they’re 100% natural, and appear only when a very particular set of weather conditions come together at exactly the right time: http://bit.ly/1zy8388
Awesome. I want to roll in one.