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I am curious why there aren’t any endoparasitic mammals, reptiles or birds

Endoparasite being a parasite that live In the host whereas ectoparasite lives On the host

I hope this clears up confusion

Danielle Wilson
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  • Can you please define "parasite"? Aren't humans parasites of wolves and elephants? Aren't cuckoo parasites? How about vampire bats, vampire finch, cookie cutter shark, hood mockingbird, cowbird, oxpeckers or hyena? We can largely qualify them all as parasite. Note that you might want to define reptile too (see here) – Remi.b May 21 '18 at 15:57
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    I'm voting to close this question as off-topic because it is based on a false claim that there are no mammal / bird / reptile parasites. – Remi.b May 21 '18 at 15:57
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    I mean endoparasites that are mammals birds or reptiles. I know there are endoparasites worms, protozoan sect. But I don’t think there are any mammals birds or reptiles that are endoparasites. Sorry for the confusing wording of the question – Danielle Wilson May 21 '18 at 19:07
  • If there are any, can you give examples? I don’t know of any – Danielle Wilson May 21 '18 at 19:08
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    Oh... you should definitely edit your post to say "endoparasite" then (and make sure to define the term). For the moment the post still says "parasite". No, I can't think of any example of endoparasitic mammal / bird / reptile except if you would consider a woodpecker a tree endoparasite, would you? Humans could be considered parasite of earth if you consider earth as a living organism (see Gaia by Lovelock) but that's a bit of a stretch. Intuitively I would think a big part of the answer is going to be "because they're big!" – Remi.b May 21 '18 at 19:23
  • I edited the question now to make it clearer. Thank you Remi.b – Danielle Wilson May 24 '18 at 20:42
  • @Remi.b I'm not really aware of any commonly-used definitions of parasite that would classify humans as parasites of wolves or elephants (endo- or ecto-). – arboviral May 25 '18 at 12:53
  • I would honestly suggest "parasite" is fine here, but that the question is revised to "are there any X parasites - and if not, why?" – arboviral May 25 '18 at 13:11
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    In the most clearly defined concept of parasite, a parasite and a predator are confounded. If species A have a beneficial impact on species B and species B have a negative impact on species A, then A is a prey/host and A is a predator/parasite. In such terms, yes, humans are parasite of elephants. My point was to highlight that whether or not there are mammals parasite depends upon the definition once want to use. IMO, the question now makes much more sense with the prefix endo. It still bothers me a little that the woodpecker examples is not resolved. – Remi.b May 25 '18 at 14:45
  • @remi since woodpeckers are digging into the trees to pull out and eat insects that burrow into the tree the net impact on the tree is arguable. – John May 25 '18 at 17:43
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    If I had to guess, I would say that it's a matter of basal metabolic rate. Birds and mammals are warm-blooded, and so have to breathe regularly (and eat a lot of food) to maintain body temperature. It's pretty hard to do this if you're an endoparasite, and there doesn't seem to be an obvious evolutionary route to get to a lower rate. – jamesqf May 25 '18 at 18:08
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    These sorts of "why didn't this evolve" questions are not answerable without profound speculation. – kmm May 25 '18 at 20:48

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Short answer size.

endo/ectoparasites need to be small to go unnoticed, and be hard to eliminate. The smallest mammals and birds are still much larger than a flea, fluke or other endoparasite. That's why larger parasites leave after feeding, if a vampire bat hung on the cow indefinitely the cow would eventually notice and do something, something as simple as rolling over could kill them quite effectively. While an animals infested with fleas can not do much to get rid of the fleas. The few large endoparasites either evolved from much smaller parasites (tapeworms) or exploit some strange insensitivity in the host(cymothoa) This means there is no path to ectoparasite which could lead to endoparasite.

Why there are endoparasites evolved by other means in vertebrates what exactly would they evolve from, there are no birds or mammals that would survive being cut off from outside oxygen or passing through a digestive system. It is like asking why no flying trees have evolved there just is no path to get there or from where they are now, or if there is a path it is so unlikely that it has not occured.

John
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