This is the semi-transparent eyelid of the red-eyed tree frog, Agalychnis Callidryas. Frogs aren't the only creatures with 'third eyelids' that keep their eyes moist without blocking vision completely. Sharks, cats, crocodiles, polar bears and camels have them too.

A simplified illustration of the various brain functions...

Ever seen an egg cracked underwater?

We've all struggled trying to shove magnanimous amounts of information for exams, be it vocabulary, geometry theorems, biology notes, chemistry reactions, physics equations or even just names of acquaintances we meet at weddings or the likes.  You might question whether after many years of non-stop learning, be it in a classroom setting, or just basic interactions and do's and don'ts, may we run out of space to absorb all the memories, events and information we encounter.

Our brain, unlike the brains of animals and lower ancestors, is not hardwired by instincts. In fact, we have very little in the field of instincts by comparison. Our brain is a learning brain. It is designed to absorb and interconnect information. Now, which of this inform ...

Despite slang terms that imply otherwise, the human penis contains no bones. The same cannot be said for many of our closest evolutionary relatives: Chimpanzees and bonobos both have penis bones (a macaque one is pictured, left), also known as bacula.

To find out why some primates have the feature whereas others don’t, researchers traced the bone’s evolutionary history through time. The baculum first evolved between 145 million and 95 million years ago, as reported in the Proceedings of the Royal Society B. That means it was present in the most recent common ancestor of all primates and carnivores. Why some descendants, like humans, lost their bacula appears to be due to differences in mating practices: In primates, the presence of a penis ...

The harsh desert environment is known for its scorching temperatures and scarcity of water, making it a challenging place for most creatures to thrive. However, amidst this seemingly inhospitable landscape, the kangaroo rat stands out as a remarkable example of nature's ingenious adaptations. These small rodents have not only managed to survive but thrive in the desert with virtually no drinking water. The secret to their survival lies in their unique physiological features, particularly their kidneys' specialized structure.

Generally, the majority of water reabsorption in the kidneys occurs in the loop of Henle (see illustration). This structure is responsible for the reabsorption of water and essential ions from the urine back into the bl ...