Many organisms have complicated and bizarre life cycles. Which one is the longest (most stages) in terms of metamorphosis with each individual step resulting in a visibly different organism, and which one is the most bizarre.
Are there many more yet to be discovered?
Donald Trump? (Hey c’mon, y’all were thinking it too…)
I’ve always been fascinated with periodical cicadas, which spend their first 17 years of life as tiny grubs underground drinking tree sap, then suddenly emerge en masse in locust form for a few weeks, just long enough to have sex and die.
Liver flukes have multi stage, multi host (sheep, snail etc) life stages. Its quite impressive and beats the cicadas hands down.
Any more?
Eels have an incomplete life cycle. What they do in the Saragasso sea is still unknown.
Moderator Note
Political potshots are not allowed in GQ. No warning issued, but don’t do this again.
Colibri
General Questions Moderator
Fungi have some of the most bizarre life cycles you’ll ever see. So you see the mushroom, pushing above ground when conditions are right. That’s actually the spore producing and dispersing organ of an underground organism, which mostly lives as a mass of undifferentiated, filament known as hyphae.
But wait, there’s more! The mushroom (botanically known as a basidium) is actually the sexual reproductive organ. Fungi can also produce spores asexually, and the spore-producing structures for asexual reproduction can be radically different.
But wait, there’s more! Fungal hyphae, when they encounter compatible hyphae may fuse to form what’s known as a dikaryon. That’s a fungal body that nuclei with two different genetic background. The dikaryon can exist independently for some time, years even. It’s this dikaryon that may undergo sexual reproduction, forming the basidium, the nuclei fusing and undergoing meiosis and producing spores. Or maybe not. Some species have never been observed to undergo sexual reproduction.
But wait, there’s more! Some parasitic fungi need to infect two different hosts to complete their life cycle. They also have up to five different types of spores.
A diakryon that stays a diakryon: isn’t that called a chimera?
[I’ll be good]
Most plants go through alternation of generations. Like, suppose you’ve got a tree in your back yard, and a seed falls off of it and blows or rolls into the front yard, and grows into a new tree there. The back tree is the front tree’s parent, right? No, it’s actually its grandparent. The intermediate generation was microscopic, living entirely in the (grand)parent plant.
Monarch butterflies are pretty far out there. The majority of them overwinter at a very specific spot in rural Mexico northwest of Mexico City. No one knows why they need to go to that specific area or how they find it because it takes four generations to make the round-trip from the U.S. and parts of Canada to Mexico and back. Combine that with their caterpillar metamorphosis and that is some complex strangeness.
There’s the Turritopsis dohrnii, also known as the “immortal jellyfish” because its adult form can, in some situations, revert back to the polyp stage and start over.
On monarch butterflies, there’s also the fact that the generations aren’t all the same. It takes three generations to go from Mexico to Canada, but the generation hatched in Canada is larger and stronger than the others, and flies all the way back down to Mexico.
A chimera results when you’ve got two different genetic lines in the same individual, but the cells containing the different genetic lines remain distinct. Fungi - filamentous fungi, that is, like I was talking about previously - are coenocytic. The fungal filament actually contains continuous cytoplasm with multiple nuclei not separated by cell wall nor cell membranes. The dikaryon (note spelling) will therefore have multiple nuclei of two different types, all floating together in the same filament, in contrast to the monokaryon, in which all the nuclei are the same type.
Fungi are weird.
One of my favorite quotes:
“The juvenile sea squirt wanders through the sea searching for a suitable rock or hunk of coral to cling to and make its home for life. For this task it has a rudimentary nervous system. When it finds its spot and takes root, it doesn’t need its brain anymore, so it eats it. (It’s rather like getting tenure.)”
And that’s not even counting the fungi that have a form that zombifies an insect and remote-controls it to get to where it wants to set up the stationary form.
There’s a clear winner, a dinoflagellate called Pfiesteria piscicida with 22 different distinct stages and multiple pathways which it can travel through those stages.
Look at the diagram that accompanies the Wikipedia entry
The jury is out on this one. Scientists not agreeing.
Decapodians, maybe?
Just had to get that in, didn’t you, John?
It’s OK, even by post #7 there were already some good replies.
Replying to myself here as I finally got the time to find a good video of this. The life cycle of wheat stem rust, Puccinia graminis: https://www.youtube.com/watch?v=AeuP5IYP5HA
Summary:
The fungus infects wheat and produces urediniospores, spreading disease throughout the field, and beyond.
As the growing season ends, the fungus switches to producing teliospores.
The teliospores overwinter in the wheat stubble, then germinate in the spring to produce basidiospores.
The basidiospores are released and infect a completely unrelated plant, the barberry. After the fungus has established itself it then produces pycniospores, which actually fertilize neighboring fungal lesions. Incidentally, this is where the dikaryon is produced.
The now dikaryotic fungus produces aeciospores, which infect wheat and the cycle begins anew.
Yeah, edited my other post after buddha_dave got noted, but in the end couldn’t resist… 
