The Jellyfish Problem

41 points by gruseom 5 years ago | 11 comments

ncmncm 5 years ago |

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.

pvaldes 5 years ago | |

> 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.

ncmncm 5 years ago | | |

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

disqard 5 years ago | |

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

frabbit 5 years ago |

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...

divbzero 5 years ago |

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.

frabbit 5 years ago | |

Use "cnidaria" as your keyword?

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

perl4ever 5 years ago |

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

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

cortesoft 5 years ago |

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...

huffmsa 5 years ago | |

> 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.

naringas 5 years ago |

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