These pearls are gorgeous. Freshwater pearls can take between one to six years to form, and saltwater pearls from five to 20 years. The longer the pearl stays in the shell the larger it gets due to the continuous nacre coating.
Human circadian rhythms tend to be closely tied to the rise and fall of the sun each day, occurring in fairly regular 24-hour cycles. But by no means is this how all organisms’ internal clocks operate. Science News recently compiled seven of the strangest circadian rhythms.
Yellow-eyed penguins are easily identifiable among other species because of the yellow color of their eyes. They have a light yellow stripe around each eye that continues and joins in the back of their head.
Treefrogs are adapted for an arboreal (in the trees) existence, with long limbs and digits that help them cling to twigs and bark. They also have large suction pads or adhesive discs at the tips of their toes,…