4Watchman Fish and Pistol Shrimp Are Roommates
The shrimp goby, or "watchman fish," is a cute little bug-eyed fish so named because it shares its sandy burrow with a species of smaller "pistol shrimp," a cute little crustacean so named for packing a sonic freaking rifle in its claws. The deadly shrimp hasn't just moved in with the bigger fish, but created the entire burrow itself, taking the extra time to build it just wide enough for its scaly friend to live. It's just like the classic TV series The Odd Couple if Tony Randall fired sound blasts from his fists.
What the Huh?
A speedy fish with large, sophisticated eyeballs is pretty well equipped to evade predators, but can do little to build and protect a permanent nest. A burrowing shrimp with an atomic cannon in its arm is pretty equipped for home security, but happens to be terribly nearsighted.
Put these guys together, and you cover all the bases needed to keep off the seafood menu. While the shrimp provides the boarding and protection, it uses its long antennae to keep in constant contact with its seeing-eye-fish, kind of like a blind guy with a shotgun. The shrimp will even build a pad large enough to accommodate the goby's girlfriend, who will move in to raise a family and probably break up the band just like his buddy the pistol shrimp told him she would, man.
3The Oklahoma Brown Tarantula Keeps Toads as Pets
To a spider the size of a hairy, mutant child's hand, soft little frogs and toads are just another tasty meal that can do nothing to fight back. And to a soft little frog or toad, a baby spider is just as appetizing as a fly. This equation of mutual destruction is presumably no different for the Oklahoma brown tarantula, and the the Great Plains narrow-mouthed toad. Which makes it so strange that in the wild, Oklahoma brown tarantula burrows are often home to one or more of these inch-long toads. The two species manage to ignore the sign that blinks "Prey! EAT!" every time they pass one another in the hall, grudgingly respecting one another's fatal vulnerabilities much like the relationship between you and your cat.
What the Huh?
The little froggies devour any tiny bug other than freshly-hatched Oklahoma spiderlings, and are in turn left in peace by the monstrous momma spider. Why? Because narrow-mouthed toads are primarily adapted for eating ants, and a giant arachnid can defend its home from ants about as well as you can punch out bacteria. So the toad eats the tarantula's enemies, and in return it gets an armor-plated, venom-drooling roommate most frog-eating things would rather not mess with.
So we weren't just making a lame cat joke up there. It really is literally the same relationship; these spiders have learned to tolerate a tiny amphibian for the exact same pest control service that first brought together humans and felines. There's no word on whether or not aging, barren spinster spiders just surround themselves with toads and let them piss all over the ottoman, so we're going to go ahead and assume they do.