In most cases, you can expect the child form of a creature and the adult form of a creature to be rather similar. Kittens look like cats, puppies look like dogs, etc. This isn't always the case, though, such as in certain insects that go through metamorphosis. The most obvious example is caterpillars becoming butterflies, but there are even weirder examples.
Naturally, fiction has played with the concept. It's not an uncommon occurrence for parasitic grubs to become giant lizards, or fuzzy rabbitlike creatures to grow up to become bearlike behemoths. If you weren't told they were the same creature, you never would believe it.
Naturally, the most extreme cases present a problem for artists. How do you go about creating the intermediate stage between an insect and a dragon? In many cases, they don't bother. The transitional stages are either never shown onscreen, or the creature will use a form of cocooning that prevents the audience from seeing its metamorphosis.
If the adult form is significantly stronger, this can act as a species-wide Magikarp Power, but sometimes the different forms are dangerous in different ways. While this is often used for a species-wide One-Winged Angel or to introduce more powerful forms of old enemies, occasionally it's just for weirdness' sake.
See also Metamorphosis.
- Most officially defined evolutionary lines in Digimon fall under this; lines with a consistently maturing appearance are the minority and are generally specifically designed as protagonists of an anime series. Perhaps the standout example is Patamon of Digimon Adventure, who evolves from a vaguely-defined small orange flying meatloaf/batpig mammal thing into an angel. In the broader canon, most Digimon have a wide variety of forms to which they can evolve, generally not restricted to specific lines, and so pretty much any and every Digimon can be an example of this.
- And it gets worse than him. His line is at least pig thing with ribbon ears > pig thing with batwing ears > angel > bigger angel. However, Gatomon's is puppy > cat > angel > dragon.
- There are also situations where the onscreen evolution is not the most obvious one from the cards or games. Take Gotsumon, a child-sized Rock Monster. In the card games, he has a moderately developed evolution line that consists of Palette Swaps (he evolves to Icemon and Meteormon). In 02, however, he instead becomes the rhino-like Monochromon. Now, Monochromon (Champion-level) has its own Palette Swap evolution Vermillimon (Ultimate), but in Digimon Frontier and Digimon Data Squad, different Gotsumon appear who evolve into Meteormon, which suggests that Monochromon can branch back into Gotsumon's Palette Swap line.
- Go look up evolution lines on a Digimon wiki (like Wikimon) and see how many different evolution possibilities there are.
- Cell from Dragon Ball Z evolves from a half-insect, half-lizard monster to an humanoid android. His intermediate stage is a vaguely humanoid hulk, who for some reason lacks the wing that both his initial and final stage have.
- Gosamyr, a friend of the New Mutants, was a member of an alien race whose members undergo through this. At first, they're cute, delicate, winged creatures (although with the annoying ability to empathically - and involuntarily - cause conflicts among male humans), but then they enter the cocoon phase (which lasts centuries) which would turn them into their adult form: gargantuan abominations.
- The Aliens from Alien also have a peculiar lifecycle: It could be described as haplodiplontic, with the "gametophyte" being a creature that could be described as a mismatch of hands/legs, tail and genitalia that lives just to seek a host to impregnate, and the "sporophyte" developing in the body cavity of the host, emerging violently as a snake-like creature, and quickly growing up into a large, 4-limbed biomechanoid creature with some traits reminiscent of the host species, but taller and slimmer. If it grows into a fertile queen, it also changes its limb structure, grows an additional pair of arms, increases in size, and loses the host-like characters.
- Gremlins: The Mogwai multiply if gotten wet, and transform if fed after midnight.
- Hedorah in Godzilla vs. Hedorah.
- Likewise, there's Destoroyah who went from a colony of microscopic crab-things to a giant scorpion-crab thing to a giant demonic crab-thing.
- Mothra and Battra, naturally. Both are giant caterpillars who then become giant butterflies.
- Godzilla vs. Biollante has the titular Biollante as another example, going from a giant rose to a bizarre crocodile-Godzilla-tree-thing.
- And then there's the mutant clone Spacegodzilla who can switch between his "normal" Godzilla form and his crystal form of the monsters listed he, Desotroyah, and Hedorah are the only ones, not counting mechs like Super-Mechagodzilla and MOGUERA, that can switch back and forth between forms and they take full advantage of this. Often switching into a previous form and using a different means of attack when head on attacks are proving not useful.
- Godzilla himself "evolves" over several forms in Shin Godzilla.
- Irys from the film Gamera 3: Awakening of Irys goes from a strange-looking yet somehow adorable snail-like creature with tons of tentacles to a giant bipedal monster with tentacles with spears on the ends, swords for arms, and a cone-shaped head with a single glowing eyeball.
- The Graboids of Tremors go through a multi-stage "alternation of generations" metamorphosis similar to the aformentioned Xenomorphs, hatching as slug-like "dirt dragon" larvae, which grow into the familiar bus-sized Sand Worms, which spawn numerous bipedal Shriekers sporophyte-style, which metamorphose into the winged, egg-laying Ass Blasters.
- Inheritance Cycle has a humanoid species named Ra'zac. They ride big winged creatures, which are the next step in their life cycle (and their parents).
- In Animorphs, the Skrit Na come in two forms: the Skrit, which is basically a huge and not-too-bright cockroach, and the Na, which are The Greys (and also not very bright). The Skrit is the first phase, which eventually goes into a cocoon and dies, with the Na emerging from its body. Nobody seems to know where new Skrit come from.
- Implied in Everworld: the Coo-Hatch, a vaguely-humanoid race from another universe, are always accompanied by weird little flying insects. The human protagonists suspect that those might be young Coo-Hatch.
- Dwarves, of all things, in A.R.R.R. Roberts' The Soddit become wizards, who in turn become dragons.
- In Series 3 of Primeval, the team encounter a nastily infectious fungus that converts its hosts into hideous mutants which of course are infectious as well.
- The Kamen Rider franchise has several Monsters of the Week who invoke this trope. Most of them are based on insects:
- The Shereghosts from Kamen Rider Ryuki resemble humanoid larva. They later undergo metamorphosis in a cocoon, turning them into Raydragoons, which are humanoid dragonflies. The Movie adds another transformation, looking more like an actual dragonfly, albeit mechanical.
- The Worm from Kamen Rider Kabuto have this as their shtick. The most common variant of them is the Salisworm, which looks like a pupa with arms and legs. Some Salisworms are able to shed their skin, turning them into stronger forms that resemble humanoid arthropods. This process is known as molting.
- The Yummy in Kamen Rider OOO look like mummies until they consumed enough of their host's greed, in which case they transform into a humanoid animal or sometimes even a giant monster.
- The Inves from Kamen Rider Gaim really take the cake with this. They first start out as strange humanoid bug things. If they consume enough Helheim fruit or Lockseeds, they turn into a humanoid animal. If they continue to eat fruit or lockseeds, they transform into huge beasts. Later, the Inves are revealed to have been regular animals and, in some cases, even humans who were irreversibly mutated after eating Helheim's fruit, adding another layer of metamorphosis.
- Quite a few Pokémon have a variant of this with their evolution. The most obvious example is Magikarp to Gyarados (Small carp to giant sea serpent), but there are others, such as Trapinch to Flygon (Ant lion larva to adult to dragon) and Feebas to Milotic (fish to elegant-looking sea serpent), or the bizarre Remoraid to Octillery (remora to octopus).
- Bizarre, but explanatory: Remoraid (pistol) to Octillery (cannon)
- And, of course, most of the bug pokemon.
- According to Metroid II: Return of Samus, the eponymous Metroids of Metroid, while on their home planet at least, go from floating parasitic jellyfish to beetlelike creatures to giant armored lizards. In an interesting twist, the first stage is not only the most well-known and arguably most dangerous, but while nearly every game has a variant of the jellyfish stage, the later stages have only appeared in a handful of games. Apparently their larval stage can become mutated in various ways from the chemicals and radiation in its surroundingsnote , and they can only complete their normal life cycle on planet SR-388.
- Also, according to Metroid: Other M, Ridley's larva form is a small rabbit-bird-thingy, which then becomes a feathered lizard kind of creature before finally evolving into the space dragon we all know and love.
- Varkids from Borderlands 2 Spawn as larvae from nests. They accelerate their life cycle in response to trauma (damage). The cocoon stage in between metamorphs is extremely vulnerable.
- Resident Evil:
- In the Wii version of Resident Evil 1, Zombies mutate into Crimson Heads if not burned or decapitated after death. According to lore, Crimson Heads mutate into Lickers, but it's not a game mechanic.
- William Berkin from Resident Evil 2 mutates heavily throughout the game, going from a hulking not-zombie with an eye in his shoulder to a Blob Monster by the end. It took a nuclear blast to finally kill it.
- The Nemesis Tyrant from the game named for it gets more and more mutated as it's symbiote gets angrier.
- Ganados and Manji from Resident Evil 4 and Resident Evil 5 respectively have a slim chance to disgorge their Puppeteer Parasite upon being killed.
- Javo Zombies from Resident Evil 6 are afflicted with a wildly mutagenic version of Virus du Jour, which synchronizes with their Healing Factor to result in them growing back lost arms as various kinds of swords, broken ribs as bone armor or poison-spewing tumors, etc.
- The Fodder from Dead Space 3 spawns Combat Tentacles from its waist when dismembered enough. If it's arms get removed, it replaces its torso with three whips. If it loses its legs, it gets a Spike Shooter for each one. Removing one arm and one leg usually kills it outright.
- The Monsters from Evolve all have this as their shtick; they grow stronger by consuming animals, also becoming larger and spiky with each progression. They start out weaker than the human hunters out to kill them in the first stage, are roughly equal in strength during the second stage, and exceed them in the third and final stage.
- The Zerg from StarCraft are spawned as catterpillar-like Larvae. They can then mutate into several different kinds of monster, themselves sometimes able to become something worse. And they evolve on a personal level, with sucessful mutations applied to the baseline.
- In Fe, the young Lizard Folk that the eponymous protagonist befriends early in the game look and behave dramatically different from their adult counterparts encountered later on, which take the form of large frilled snakes with manes and antlers. Taken a step further with their overlord, who is a mountain-sized sea serpent.
- In Sluggy Freelance Aylee has gone through this over a dozen times, eventually turning into a fifty foot tall dragon and finally into the most dangerous creature of all ... a woman!
- Starslip features the Jinxlets. Adorable little bug creatures that gain nourishment from cuddling. When fed Royal Jelly, however, they turn into terrifying berserker engines of destruction.
- The "Jayslob" from Awful Hospital constantly mutates throughout Fern's battle with it. We get to see it metamorphosize in real-time, thanks to Bogleech's love of Body Horror.
- A Space Ghost episode had Jan and Jayce adopt a cute l'il creature called a star fly, unaware that it was the larval form of a giant glowing Kaiju called a star beast. It grows up fast and seems threatening, but in the end, it remembers Jan and Jayce and refuses to hurt them.
- Played With in Steven Universe, as Rose Quartz mentions that she was surprised to realize that children and adult humans were even the same species. Her species are Born as an Adult, so it never even occurred to her that something could change so much over its life cycle.
- In Futurama, the crew discover a mysterious but delicious food that looks exactly like popcorn shrimp, just filling up holes on another planet. They sell it on Earth and it becomes hugely popular...which is bad, because it turns out those are baby Omicronians, and the parents are naturally miffed at the Earthicans for eating their children.
- There are tons of critters with weird life cycles. Insects, for example, lay eggs that hatch into worm-like larvae, who gorge themselves until they can spin a cocoon around themselves. That itself hatches into a mature adult. There may also be sub-stages of larval development, called instars.
- The other method is Nymphs, which are flightless, usually aquatic mini-versions of an insect that eventually grow wings and lungs.
- Similarly, frogs start out as fish-like tadpoles. Eventually, they grow into four-legged amphibians.
- Plants can have a "haplodiplontic" life cycle, which is kind of like "seeds that spread spores by fertilizing themselves, and can also clone more haploids".