Elephants can smell water up to 3 miles away. Rabbits can see behind themselves without turning their head. Goldfish are the only animals that can see in ultraviolet and infrared light. Mockingbirds are able to imitate sounds. The ninja slug shoots calcium carbonate "love darts" tipped with hormones increasing the chance of mating. The North American opossum can play dead, called Thanatosis, but also has LTNF (Lethal Toxic-Neutralizing Factor) which actively seeks and destroys toxins in the body. Pistol shrimps can shoot a bubble capable of stunning or killing their prey. This bubble can travel at 60 mph, generate a sound of 218 decibels (160 = ruptures human eardrum), produces an acoustic shock wave, and the heat of the byproduct vapors can reach 4700 Celsius (surface of the sun is 5500 Celsius). Mimic octopus takes on the shape of other animals to deter predators. The axolotl has pretty much superhero healing (few months to recover an entire limb), even able to heal a damaged brain. The immortal jellyfish, or Turritopsis nutricula, by using trans-differentiation can basically revert from adult to baby to adult to baby in an endless cycle.
massive fluffy ears for directional hearing chameleon skin to change colour for camouflage the ability to shoot noxious vomit out of vents to the sides of your nose like a fulmar on the gag reflex - Geese don't have a gag reflex which is why they are easily force fed in the production of foie gras and if we are going down the X rated route the paper nautilus has a detachable penis which breaks off and remain inside the female ... as nautilus also have gills you could have a male character use nautilus genes to gain gills but then discover the other side effects the hard way...
Bacteria that can withstand extreme temperatures- actually they need the extreme temperatures to survive.
Just some side facts. A flea can jump 200x its body height. Same as a human jumping over the Empire's State Building. A snail can reegrow its eyes if cut off. Oysters can change from male to female to help with mating. You can tell the gender of a turtle by the sound they make. Male grunts, females hiss. Sharks are immune to cancer. Cats can hear ultrasound. If a crocodile bites you, push your thumbs in its eyes and it will instantly let go. If you pour even a small amount of alcohol on a scorpion it'll go mad and sting itself over and over until death. BTW Killer Whales are actually a species of dolphins.
Starfish can regrow their entire body from a single cut off leg - yes, you end up with two starfish. Some reptiles have a dormant third eye on the top of their heads. As for things you can see: Giant peacock style feather display to confuse predators? Sharks just keep on churning out new teeth as they get ripped out. There are fish with transparent heads You could loose your sight but gain giant whiskers and feel your way around like some moles.
