Well I don't know if one would say they're worms as such...
The
cestoda class(a.k.a tapeworms) seem to be the only ones that justify its name. Maybe the
trematoda class too...
But even then they're not your conventional annelidas... which are a phylum in their self.
But the platyhelminthes phylum is very vast...
And as you said primitive. They lack a respiratory system, a conventional digestive system(they do have a digestive system[well, some don't, like the Acoela genus[I think it's a genus], which consumes algae and they live inside it], but it's one way[no anus, just a pharyx] and there's no body cavity/are acoelmates), are triploblastic, are hermaphroditic, the nervous system is extremely primitive, for the most part it's just a nerve cord and then a concentrated cluster of nerves for a basic brain etc.
They're very unique though and I think they teach us a lot about evolution, and such.
They're not exactly good pets or w.e considering they're microscopic for the most part and 3 out of the 4 classes are obligate parasites... But one of them isn't a parasite on mammals except the hippopotamus(monogena) and afaik trematoda don't have human hosts a lot. I've not done much research into treamatoda though.
EMZ=]
EDIT; Just read the thing about my avatar.
I always like neon colours tbh. I have a few other pictures where I've made my face neon coloured.
I like the definition in it really. Hard to explain.
Is :rofl: good?
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