Basic Trope: A species' genders have extreme differences between them.
- Straight: Male aliens from planet Troperia are small, muscular humanoids with disproportionately large arms. Females look like Human-like Green Skinned Space Babes.
- Exaggerated:
- Female Troperians are regular Green Skinned Space Babes, while males are Energy Beings.
- An entire ecosystem turns out to be a single species with hundreds if not thousands of various genders.
- Males and females are so different that even sexual reproduction should be impossible.
- Downplayed:
- Male Troperians have larger arms than females, but are otherwise quite similar.
- Troperians are visually identical regardless of sex, but only the males are capable of firing Eye Beams as a mating display.
- Justified:
- Troperians evolved so that the males gather large amounts of materials in small caves, so being short and muscular was a trait acquired through natural selection, while females being taller allowed them to reach food in trees more easily.
- Their hormones affect their appearance.
- Sexual selection is to blame. note
- Males tend to be small and flying to reach more partners. Females are too heavy and large to fly but can lay far more eggs.
- Troperians are based on a real animal species that actually does have drastic sexual dimorphism.
- Inverted:
- Bizarre Sexual Monomorphism
- Male and female Troperians are completely identical, even down to the genitalia.
- All Troperians are hermaphrodites - there is only one gender, even if some appear more feminine or masculine than others.
- Subverted:
- Two characters, Aliice and Bohb, are a female and male Troperian respectively. Aliice is a Green-Skinned Space Babe, and Bohb is small with giant arms. The rest of the cast assumes that all Troperians are equally dimorphic. However, a visit to planet Troperia proves that this is not the case; Bohb is just deformed.
- Male troperians are covered in scales while the females are covered in feathers. It turns out that it is just a result of social constructs. Males pluck out all of their feathers and let their skin underneath harden into scales. Females style their plumage. If they both left it natural they would look identical.
- Double Subverted:
- The genders have extreme psychological differences; females are extremely aggressive and will kill anyone on sight, while males search for food and are non-violent.
- It turns out that Troperians used to be far more divergent. After the giant arms were rendered obsolete, the small size a hindrance, and the feature weren't even considered attractive Troperians used genetic engineering so that males could have a more useful while still being fertile. Bohb's appearance is a throwback to them before modification.
- Parodied: Female Troperians are green skinned space babes, while males are basically nothing more than giant writhing masses of genitalia and pulsating sacs of algae. Female Troperians are quick to point out how all men are scumbags that only think about sex, oddly enough.
- Zig Zagged: A researcher attempts to find out which Troperians are male, and which are female. After much observation, he discovers the differences and similarities...only to be shot down again when a nearby tribe completely inverts what his notes say which gender is which. After even more observation, one Troperian who speaks the researcher's language tells him that "our entire species consists of hermaphroditic shape-shifters", rendering all of the researcher's notes moot.
- Averted: Troperians genders are differentiated by the same traits as humans.
- Enforced:
- Male Troperians were first depicted with bulky animatronics. Female ones were manufactured but ended up defective. They were short on both time and budget so they had to substitute make up on an actress.
- The creators of the work needed it to be obvious which Troperians were male and which ones were female.
- Lampshaded: "Are you two even the same species?"
- Implied: A screen lists the recovered specimens from Troperia. The male specimen is half the height of the female one.
- Invoked: A Mad Scientist in creating an artificial species, purposefully gives both sexes vastly different physical characteristics.
- Exploited: Aliice and Bohb are two different species. They need to stall and make an armistice with the Arbiters of Purity to buy more time to build a coalition. The actual aliens facing invasion couldn't make it. They claim to be the same species but more divergent sexes to both explain their divergent appearance and avoid admitting to interspecies cooperation that the Arbiters find abhorrent.
- Defied: Not applicable. (This trope is beyond the control of the characters.)
- Deconstructed: The actual biological costs and downsides of said dimorphism are brought to the forefront. Cross sex organ transplants are outright impossible for one and they suffered a Gender Cide which results in there being far more of one than the other.
- Reconstructed: Troperians invent artificial reproduction and everything works out fine.
- Discussed: "It is funny, we think that but men and women are pretty different but we're nearly identical compared to some of the species. Troperian men look like oak trees with a squid attached while their women look like fur covered nagas."
- Conversed: Alice is watching Trope Trek and sees the alien of the week. She turns to Bob and says, "Wow, what did these guys evolve from? Anglerfish?"
- Played For Laughs: Generations of Ugly Guy, Hot Wife has resulted in future human males being gonks and future human women all being supermodels. Men who look anywhere better than average or not incredibly attractive women are considered primitive freaks.
- Played For Drama: The Troperian society is extremely sexist, justified by the dimorphism.
- Plotted A Good Waste: It's foreshadowing that Aliice and Bohb are just pretending to be Troperians.
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