7 Amazon River Dolphin
You won’t find this dolphin out at sea; it is one of the few remaining freshwater dolphins on Earth. It is found in rivers and lakes throughout South America including the Amazon River. These dolphins are big animals, weighing up to a hefty 350 pounds (160 kg) and stretching up to nine feet (2.7 m) long, but they don’t have the typical dorsal fin associated with dolphins.
Unfortunately, because the dolphin eats the fish that river fishermen want to harvest for a living, the animals are often deliberately killed. They are also the source of many myths. Local legend says the dolphins are quiet, solitary, and blind, but scientists have shown that they are in fact sociable—even quite aggressive—and have full vision.
The dolphins range from gray to the pink hue that they are known for, and scientists have observed that the pink color emerges as the animals age, with male dolphins having the rosiest coloration.
One working theory is that the pink of their skin is scar tissue from the frequent fights the grown dolphins engage in. Others have guessed that the pink coloration is an evolved response to blend in with the red sand in the riverbeds of South America, in order to hide from larger predators.
6 Lake Hillier, Australia
From the sky, Australia’s Lake Hillier looks like someone emptied several vats of Pepto Bismal onto the landscape. It’s strikingly pink. The source of its color is the same algae found in the salt ponds of San Francisco: the salt-loving Dunaliella microbe. It has pigment compounds that make it particularly good at absorbing sunlight, which helps create the reddish-pink color.
Scientists have found a mix of other algae and bacteria that have helped intensify the pink color of Lake Hillier. These discoveries also point to the reason for the lake’s coloring—the additional microorganisms are evidence that the lake was home to a leather tanning station in the early 1900s.
So, this particular example is half natural, half manmade; the lake’s color is particularly vibrant because of human activity.