Evolution. The inevitable effect of a planet with (as far as we know) carbon, oxygen and water. Other needed factors are : an atmosphere between 0-10 Atm(pressure), gravity between 0-9 G and a pH between 0-10.
Evolution has created a vast amount of creatures, some stranger than others. Lets have a look at some of these "strange" creatures.
bile. Shown to the left is a Prasinohaema virens, popularly called the Green Green-blooded skink.
Its native to New Guinea.
The Dumbo octopus, I almost laughed the first time I saw it. I mean, WTF?! It looks like the creatures in Pacman.
Here is a Pelagic octopus. Looks like an alien if you ask me.
I think the one in the picture isn't full-size, google the species and judge by yourself. Some species of octopuses have blue blood, due to the fact that instead of hemoglobin (which uses ironatoms), they have other proteins that bonds with copper, hence the blue blood.
This is the Blobfish, Psychrolutes marcidus. Blobfish are found at depths where the pressure is several dozens of times higher than at sea level, which would likely make gas bladders inefficient. To remain buoyant, the flesh of the blobfish is primarily a gelatinous mass with a density slightly less than water; this allows the fish to float above the sea floor without expending energy on swimming. The relative lack of muscle is not a disadvantage as it primarily swallows edible matter that floats by in front it.
This is the Colossal Squid. As the name indicates, its even bigger than the Giant Squid. The largest know example weighed over 495 kg (1,091 lb). Holy shit.
It seems as if the strangest creatures in our world is found at sea! I wonder how many more unbelievable species can be found at the bottom of the sea, the Mariana Trench for example.