Bizarre Alien Biology is a otherness trope that shows up most commonly in science-fiction TV and movies. It usually stems from budgetary and costuming issues - when you can't afford to have anything more elaborate than Human Aliens or Rubber Forehead Aliens on your show, you end up trying to make them seem less human via biological plot devices. From a scientific viewpoint, this just stretches credibility, as there's no in-character reason why aliens should have human-looking faces, and it's hard to justify "they look just like us, but they're all squid-and-volcano inside". Not that logic or science ever stopped Hollywood.
Beyond the goal of making a green-skinned space babe seem more exotic, this trope also serves another function. It communicates either that Humans Are Special or that we're just Puny Earthlings, depending on whether the Bizarre Alien Biology hinders or helps the species that has it.
- Alien Blood
- Alien Lunch
- Bizarre Sexual Dimorphism
- Hollywood Science
- Redundant Organs
- Starfish Language
- Uncanny Valley
Game and Story Use
- Your game doesn't have budgetary limitations, and the visual effects happen inside everyone's imaginations. Which means there's no need to restrict yourself to only humanoid aliens - why not go the Starfish Aliens route instead?
- If you're using a published setting based on source material that already used this trope, then it's what your players will expect, and you'd better deliver.
- Star Trek is a great example. Aliens with two hearts, green ice-water for blood, and telepathy can logically get it on with humans and produce viable offspring. If you wrote out Mr. Spock, and the Vulcans (and thus Romulans) in general, it wouldn't feel much like Star Trek any more.
- While we're on the topic of Hollywood Science, it should be noted that Space Does Not Work That Way. See also our Astrophysics page, so that you can get the science right.
- If you're into that kind of thing. For some people, and some campaigns, scientific accuracy is a very low priority. Whatever is fun to you.