Saturday, 13 January 2018

zoology - Can a lizard shed a regrown tail again?



Some lizards are famous for their ability to voluntarily shed their tail to elude predators (Autotomy). After a while, the tail will be regenerated, though with slightly different qualities, as visible in this photograph:


(source)


My question: Can this regrown tail be discarded again voluntarily, or is it a one-time feat?



Answer



Short answer: many species can drop a regrown tail again and again again, however a few can only drop it once, while some lizards cannot drop their tails at all. It all depends on the species.


Background information:


According to this site the tail will only be able to be shed above the site it originally broke off. Although according to UCSB there are a few species of lizard that only have their tail grow back once.


Every site I've visited has said that the tail is nearly a completely different structure than the one it originally had. The original tail has "score marks" (fracture planes) which were studied by Sanggaard et al. (there are a few figures that you can see in their paper).


However, according to W. N. F. Woodland, D.Sc. (Lond.), there is no apparent limit to the amount of times a Gecko can drop its tail, "save the longevity of the animal". His paper goes into great detail, and has a lot of information about autotomy (limb dropping) of the gecko. I highly recommend going through it if you're interested.


So tail re-dropping looks like it primarily depends on the lizard that you're studying.



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