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No. 71472
File 135974128385.jpg - (64.60KB , 640x360 , bilateral gynandromorph.jpg )
>>71462 right. live birth and parental investment allows us to skip the larval form. egg-laying animals can also get around it by having larger eggs with tougher shells and more nutrients, which gives more time for the young to develop inside. larvae are basically free-living fetuses, and they are that way because there is not enough to sustain growth inside their eggs and a squishy egg with no guardian is a free meal for predators; they need to move and eat even though most of their body is still extremely underdeveloped. then they pupate when they have stored up enough energy to finally be "born" into the adult form, if they are arthropods, or in the case of other invertebrates, amphibians and fish they gradually stack on adult traits until they become adults. some animals also have a larval stage capable of moving so they can disperse themselves because they are sedentary as adults, but that kind isn't relevant to this discussion.
whenever something present in a larva is no longer needed as an adult it atrophies and is reabsorbed into the body and used to construct things that aren't useless. it's extremely inefficient to keep a structure that does nothing on as a "scar" in the adult form, especially when it is something like a whole fucking limb. if it stays, there is a reason it stays. for example, the gills of the axolotl and mudpuppy are fully functional holdovers from larval forms because they are fully aquatic salamanders. i don't care if people keep the extra pair of limbs but for god's sake don't say they do nothing.
re: nipples, the reason why male mammals have nipples even though they will never be used for rearing young is because they develop simultaneously with the rest of the skin, which occurs before sex differentiation of the fetus. some animals are designated male or female from the very beginning (leading to stuff like this butterfly), but we aren't. the mammary glands and nipples are the same in males and females all the way up to puberty too, and there isn't any selection pressure for men to lose nipples when they start developing secondary sex characteristics, if that is even possible for us, which i don't think it is. it's not the same as larval structures either because they don't actually have any use until the animal is an adult.
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