The hybrid is a giant spider with a human-like closed circulatory system, calcified bones, a complete muscular system attached only to the bones, growing skin, kidneys, efficient lungs where the tracheae should be, and a womb. They also have a legless human part which sits on top of the prosoma, which has no large intestine, with the small intestine connecting to the foremost portion of the spider intestine. The end of the spinal cord also bends forwards to the spider brain

The development starts with a spider egg that has a chorion. The cumulus extends out of the spider and forms a human inner cell mass there, which develops in the egg like a human embryo, except that the hypoblast stays attached to the spider part, and the mesoderm doesn't spread beyond the umbilical cord or the skin of the spider. The egg implants into the womb and has a placenta like a human embryo. The cloaca does not form, and the yolk stalk becomes an extension of the small intestine and connects to the spider's intestine, with the portion of the gut beyond the yolk stalk forming a structure like the urachus. The neural tube also extends with the yolk sac down into the spider part, and connects to a ganglion, which becomes the spider brain. The outer portion of the yolk stalk decreases as it folds with the intestine, so that the end of the human embryo is on the top of the spider embryo's prosoma. The skeletal systems grow together, and then they continue developing until they are born. At birth, the human part can support itself, and the spider part can do most things that a spider could

Could this embryogenesis work?

  • $\begingroup$ Google "Anatomically correct Arachne" $\endgroup$
    – user75689
    Commented May 23, 2020 at 20:27
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    $\begingroup$ This question asks specifically about the embryogenesis of a hybrid, whereas that question asks about the evolutionary history of a realistically evolved creature $\endgroup$ Commented May 23, 2020 at 20:46
  • $\begingroup$ I wonder why the downvotes here. This is an excellent question, and even if it were a duplicate from the anatomically correct arachne one (which it isn't), that still wouldn't be reason for a downvote. $\endgroup$ Commented Jun 29, 2020 at 19:44

2 Answers 2


No, they are much too different animals for it to work, and even if it did, the two animals' bodies work so differently that it would not survive long at all. The best you can do is modify a human's genome to make it so that parts of its body resemble a spider.

  • $\begingroup$ But what if we assume that it can survive as an adult? $\endgroup$ Commented May 23, 2020 at 18:37
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    $\begingroup$ @IchthysKing It can't $\endgroup$ Commented May 23, 2020 at 18:48
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    $\begingroup$ the embryology is also completely different, down to at least the blastula stage, humans are deutrostomes and spiders are protostomes. $\endgroup$
    – John
    Commented May 24, 2020 at 2:02
  • $\begingroup$ @John, like I said, they are too different for it to be remotely plausible. $\endgroup$ Commented May 24, 2020 at 3:44
  • $\begingroup$ @John That isn't a good distinction, as humans seem to have no blastopore, and in spiders the blastopore forms the back $\endgroup$ Commented Jun 29, 2020 at 15:39

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No, but you can make cell implants.

Develop an egg which can hold both a spider and a human and they will probably be able to grow in the same egg. Giving you a person and a spider born from the same egg, twins of different species.

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    $\begingroup$ Welcome to Worldbuilding. It would be great if you could explain the connection between the picture you posted and your answer in more detail. $\endgroup$
    – David258
    Commented Jul 16, 2020 at 11:10
  • $\begingroup$ This wouldn't work because the eggs of spiders and humans are too different to be compatible. $\endgroup$ Commented Jul 16, 2020 at 14:38

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