While the Moray Eel looks like it's perpetually waiting for the pity laugh after it told a terrible joke, it's pretty much a ferocious underwater killing machine. Lurking in caves and crevices, it needs to strike quickly when prey is unfortunate enough to swim by. This second pair of teeny tiny toothy jaws emerges from the eel's throat when it bites down to make sure that before prey has a chance to get away it's already deep in its gullet, contemplating the lengths evolution will go to make sure you have a terrible day.
Here's a video of a knowledgeable person explaining it:
Oddly enough, when asked about the double-jaws, H.R. Giger said that he was unaware of the eel's adaptation when designing the Xenomorph. It just goes to show you that an idea as simple as "more teeth what where your teeth are" is too good to pass up.
Forget everything you learned about naked mole rats on Kim Possible.
Just like the bloated matriarchal mama in Aliens, the naked mole rat queen is the center of its society and the sole source of new offspring for its hive. In every mole rat colony there is only one larger female queen who is surrounded by a small number of breeding partners, every other member of the cluster (usually up to 80 individuals) is a sterile worker. While living underground in harsh low-oxygen environments, these mammals can survive despite being phenomenally inbred due to their hardiness and social cooperation.
This is pure conjecture, but I also believe a giant naked mole rat queen would be equally capable of sneaking onto an escaping spaceship despite the fact that it's enormous and to not notice it would be stupid as hell
It turns out there's a bit of a debate in the Alien fandom over the exact nature/purpose of the yellow burning acid they excrete. Some say it's their blood, others say it's a defensive fluid that flows just beneath their skin. Another common question is how do they contain a substance that can eat through solid steel within their bodies? Here on earth the bombardier beetle already has it all figured out without even calling in Stan Winston for help. This bug can fire jets of boiling hot liquid by storing the two reactants safely and separately, only mixing them together when needed. In the presence of catalysts in the beetle's firing chamber, the two chemicals create an exothermic reaction. This searing hot blast of gas and bug juices fires out of its rear, attacking anything it perceives as a threat or a meal. Imagine you could fart on command in any direction with the force of a hadouken, and you're almost there.
Here's the little poot machine in action:
Something wriggles. First it's subtle, almost imperceptible, but then the pressure grows until finally your flesh gives way and a new life form bursts out. Congratulations! You're the proud mommy of a healthy botfly. While other flies lay their eggs in dead stuff, the botfly's larva makes its home in the skin of very-much alive creatures. After munching on muscle and tissue for a while it emerges.
Want to know what it's like to get larva'd? Listen to this audio clip from WNYC's Radiolab
I have bravely resisted puking so many times while writing this article. Yet just THINKING about the rainbow of horrors that is the parasitoid wasp family is making me want to blow grade A certifiable chunks right now. There are so many varieties of these things and each one is tailor made to be another species' worst nightmare.
Let's say you're a normal bug, crawling around and minding your business when all of a sudden a flying angel of death jams a few hundred tiny eggs directly into your guts. It's seemingly fine at first, but as the larva grow and grow, you become a bloated gestation sack until the bugs decide they're bored and explode out of you.
Here's where the comparison gets better. You know how in the Aliens franchise there's always the one robot or scientist that falls in love with the Xenomorphs? They usually give some speech about how it's "the perfect being" or other such nonsense. Well a similar thing happens with caterpillars, which are known to protect the very parasites that just infected it:
I haven't witnesses a relationship this unhealthy since my sophomore year of college! Ha-ha!
Oh god, I'm puking.
The hagfish is a bottom feeding scavenger that feeds on wounded and dead animals it finds near the sea floor. Scientists can't figure out if it's a fish that lost its fins, or if its design is so primordial that it preceded modern lobed fish entirely. Oh, and one more thing, it can produce gallons of translucent goo with alarming efficiency. If a wandering predator tries to make a meal out of a hagfish, it soon finds that its mouth and throat are overflowing with the mucus-like excretion and it begins to choke. The hagfish's main defense is like a sneeze, but all over its body and lasting for several seconds.