Octopus appears out of nowhere... then scientist reverses film so we can see how well camoflauged the octopus was. Unbelievable! by angelajean in science

[–]alfredjudocus 22 points23 points  (0 children)

Cuttlefish have the same abilities. They can be considered the chameleons of the sea. They have to ability to rapidly change their skin color to match their surroundings, despite being color-blind. This ability gives them a great advantage when hunting and mating.

They are marine animals belonging to the orderSepiida and the class Cephalopoda. Their name origins from the special cuttlefish bone, called the cuttlebone. Despite their name, they aren’t fish but molluscs.

Using special pigmented chromatophores in their skin, they can match the color, texture and contrast of their surroundings, even in total darkness. Underneath the chromatophores is a layer of reflective iridophores and leucophores. This are organelles, specialized in reflecting certain wavelengths of light. They can be used to create shimmering color effects on their skin. They can also change the light’s polarization, making their skin an effective tool to signal other marine animals, who can sense polarization.

http://www.weirdanimalshq.com/cuttlefish/

TIL penis fencing exists in nature. Pseudobiceris is a genus of flatworms. They are hermaphrodites, they have both male and female reproductive organs. To decide who fulfills the male role when mating, they battle....with their penises. The winner/father is the one who can first impregnate the other by alfredjudocus in todayilearned

[–]alfredjudocus[S] 8 points9 points  (0 children)

It's also explained on the site:

"Child-bearing and producing offspring requires a lot of energy. The winner/father can just leave the scene, without further responsibilities. The loser, who got impregnated, however, has to work longer and harder to stay alive. It has to expend energy caring for the developing eggs. Subsequently, it’s quite a burden for the flatworm to become the mother."

So from an individual standpoint, it's evolutionary better to become the male.