Splice
I watched it with other biologists. A hearty laugh was had by all... well maybe not during THAT scene, and you know which one I mean. Anyway I figured the venomous tail barb was somehow derived from the sea snail DNA that was added, which is bulls**t science (there are no "genes for a stinger", it's WAY more complicated than that), but not totally un-thought-out. Sea snails can be wildly poisonous.
The creature might make a neat mini though
