The Jellyfish Problem | Hacker News Reader

The Jellyfish Problem

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41 pointsgruseom11 comments

We still have the problem of the ctenophores. "Comb jellies", they used to be, until it turned out they have practically nothing in common with jellyfish except transparency and radial symmetry. Or with anything else.

They use proteins similar to those used by other animals, but for different things. Some people think they evolved muscles and nerves entirely independently of other animals. Some people think they fell from the sky.

Whatever you think, they are astonishing in every detail. Watch videos of Beroe if you have any doubts.

Fascinating! Thank you for sharing. They really do look like alien creatures.

> Some people think they fell from the sky.

Ctenophores are a nigthmare to study. They self-disintegrate at the slightest touch and aren't well adapted to low pressure environments. Pieces of an animal being dragged from a storm before to fall again does not count as a realistic way to spread.

If you mean that they could have an extraterrestrial origin, is really unprobable IMHO. If there is an animal badly adapted to survive in the space is this.

Nobody really thinks they are storm-borne or extraterrestrial. They are just weird enough to make you wonder.

A good tour of the problems of phenotypic classifications -- which reached their heyday in the funfair of cladism. Always reminds me of Terry Pratchett's jokes about banana classification:

https://www.goodreads.com/quotes/6870748-yes-sir-but-the-lib...

The article didn’t mention phylogenetic analysis of jellyfish genes or genomes, e.g. using 16S rRNA. [1]

[1]: https://en.wikipedia.org/wiki/16S_ribosomal_RNA

A brief search didn’t yield anything on jellyfish phylogeny for me, would be curious if anyone else has information on this.

Use "cnidaria" as your keyword?

https://oceanexplorer.noaa.gov/fsts/media/DNAbarcodingCnidar...

"Since nothing could will itself to move without some sense of where it wanted to go"

https://www.farmersalmanac.com/maple-copters-everywhere-2158...

There is no 'true' category for anything.

The Categories Were Made For Man, Not Man For The Categories

https://slatestarcodex.com/2014/11/21/the-categories-were-ma...

> Thus Abraham Lincoln’s famous riddle: “If you call a tail a leg, how many legs does a dog have?” And the answer: “Four – because a tail isn’t a leg regardless of what you call it.”

Enter the kangaroo.

reminds me of https://meaningness.com/eggplant/definition

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