There is no honor among thieves. Nor is there among nudibranches, apparently.
It might not look like it in this video, but those two are cousins of sea slugs called nudibranches (pronounced NEW-dih-bronk), or nudis, and belong to the same order Nudibranchia. But that relationship won't keep one from eating the other.
Dustin Adamson, a Utah-based underwater videographer, captured the crazy undersea cannibalism between the two nudis, while diving in Anilao, Philippines, last year.
"I didn't even know they did this," Adamson wrote in the video's description. "The whole process took about 30 minutes."
According to National Geographic, this behavior isn't unusual. Found throughout the world's oceans, these squishy-bodied bottom dwellers use head-mounted sensory appendages to help them seek out food, which can include sponges, barnacles, small fish -- and obviously -- each other, particularly if it's another species. The hermaphroditic nudis can fertilize one another using either its male or female parts, a coupling which can also end with one of them getting eaten.
In his fascinating video, a seemingly benign nudibranch, the orange, spiky one (Gymnodoris aurita), sidles up to and then devours the other one (Marionia sp.) in what feels like a bad ending to an episode of SpongeBob SquarePants if it was directed by Federico Fellini.
But thankfully, Adamson edited the painfully slow consumption down to under three minutes. And since nudis' tiny eyes can't make out much more than light and dark, it's safe to say he didn't even see it coming.