In my heart, I want this to be true

But in my brain, I know it’s not.

Molluscs are no more closely related to arachnids than they are to us.

Which means…we’re all a big happy wet monkey spider family together?


  1. hemidactylus says

    So have you kicked zebrafish to the curb for the webweaving backboneless crunchies? And have you totally abandoned the book?

    Book ‘em Danio! Ok that was a bad pun. And a not so good set up.

  2. hemidactylus says

    And on a more serious note: it may be Whiggish of me to say, but though Lamarck is best known unfairly for the theory he inherited socially on how adjustments to the environs are transmitted to progeny, he actually came up with the privative label “invertebrate” which people may tend to treat as an actual grouping. Perhaps gaining a backbone is the important thing, along with gill clefts etc. at least from our biased perspective. Octopods and spiders are quite different ways of not having been in a grouping that gained a backbone. So Lisa’s lumping perhaps due to both groups lacking a backbone is unwarranted. Thank you Lamarck.

  3. chrislawson says


    Lamarck does get a bad rap. He was as you say a very highly respected taxonomist, especially of molluscs, and it is a bit odd that “Lamarckism” has become the standard term fior inheritance of acquired characteristics given that he didn’t invent the idea, wasn’t the only contemporary who proposed it, didn’t make it a central plank of his views on evolution, came up with a proto-Darwinism (complexification and adaptation were his two main forces driving evolution), insisted on a materialistic view of biology, and was vitriolically attacked by creationists of his era like George Cuvier.

  4. chrislawson says

    Also, “Lamarckian” evolution didn’t have any serious evidence against it until Weissman’s work in the 1880s — some 50 years after Lamarck’s death.

  5. John Morales says

    “Molluscs are no more closely related to arachnids than they are to us.”

    which, logically, is equivalent to

    “Molluscs are no less closely related to arachnids than they are to us.”

    Which means…we’re all a big happy wet monkey spider family together?

    Possibly. Or, no less possibly, that we’re all mutually unalike.

    There is a series known as “Galactic Center Saga” which features a post-human far future where machines take up their rightful hegemony, where one of the few remaining post-humans meets another living thing (a spider, I think) and it’s a powerful moment where they are emotionally overwhelmed by the familiarship between related living things — in contrast to the Kardashev II machine “ecology” that is the norm.

    Incidentally, I recall that (umm, in 1974) my biology textbook was “The Web of Life”.

    (Very arachnid analogy, no?)

  6. monad says

    Molluscs are a little closer to arachnids than us! Maybe at heart all protostomes are spiders, and all deuterostomes are monkeys. Earthworms are just long spiders without legs. Sea urchins are just spiny monkeys with no head or limbs. And so on.

  7. says

    I agree with monad. The most recent phylogenies show that of the three groups: the deuterosomes (which includes us), lophotrichozoa (which includes octopuses), and ecdysozoa (which includes spiders), it is the latter two that more recently share common ancestry. The Wikipedia page for Spiralia has some alternative phylogenies, all showing octopuses a little closer to spiders than either is to us. (I have said “octopuses” even though Greek friends tell me that the correct plural is “octopodes”).

  8. blf says

    Octopiders? Spidpus? Hum… Well, there’s sea spiders (who are not actually arachnids) and caddisflies (some larvae spin silk underwater) — easily enough raw material for a suitably mad perfesser to breed a few monsters…