# Do reptiles keep growing throughout their entire lives? What about birds? **URL:** \ **Category:** Factual Questions\ **Created:** [December 18, 2006, 11:37pm UTC](https://boards.straightdope.com/t/do-reptiles-keep-growing-throughout-their-entire-lives-what-about-birds/384709 "2006-12-18T23:37:24Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [December 18, 2006, 11:37pm UTC](https://boards.straightdope.com/t/do-reptiles-keep-growing-throughout-their-entire-lives-what-about-birds/384709/1 "2006-12-18T23:37:24Z")
I’ve heard from several different sources (some of them terribly unreliable) that reptiles don’t ever actually stop growing throughout their entire lives - not that they grow as rapidly as when juvenile, but just that it never actually stops. Is this true? If it is true, what about birds? Do they continue growing as well? (I’m asking because my budgerigar, which is now over a year old, appears still to be actively growing - not fast, but he’s measurably larger than he was a couple of months ago. ---
**Author:** ![Sapo](https://avatars.discourse-cdn.com/v4/letter/s/ec9cab/32.png) [@Sapo](https://boards.straightdope.com/u/Sapo)\ **Post date:** [December 19, 2006, 12:47am UTC](https://boards.straightdope.com/t/do-reptiles-keep-growing-throughout-their-entire-lives-what-about-birds/384709/2 "2006-12-19T00:47:50Z")
birds, no reptiles, most of them, yes. It also means they never “get old”; there is no theoretical limit to their life span until they get somehow killed. ---
**Author:** ![Mahaloth](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mahaloth/32/1079_2.png) [@Mahaloth](https://boards.straightdope.com/u/Mahaloth)\ **Post date:** [December 19, 2006, 1:26am UTC](https://boards.straightdope.com/t/do-reptiles-keep-growing-throughout-their-entire-lives-what-about-birds/384709/3 "2006-12-19T01:26:11Z")
[QUOTE=Sapo] birds, no reptiles, most of them, yes. It also means they never “get old”; there is no theoretical limit to their life span until they get somehow killed. [/QUOTE] Cite? It’s not enough to answer. You must also provide evidence. ---
**Author:** ![lynne-42](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lynne-42/32/3138_2.png) [@lynne-42](https://boards.straightdope.com/u/lynne-42)\ **Post date:** [December 19, 2006, 1:48am UTC](https://boards.straightdope.com/t/do-reptiles-keep-growing-throughout-their-entire-lives-what-about-birds/384709/4 "2006-12-19T01:48:05Z")
[QUOTE=Sapo] reptiles, most of them, yes. It also means they never “get old”; there is no theoretical limit to their life span until they get somehow killed. [/QUOTE] I know little about birds, except that there are certainly maximum sizes and identification is often linked to size, so these maximums are consistent for adult of a species. Reptiles, I know more about and cannot agree with **Sapo**. My cite is my own book, _Crocodile: evolution’s greatest survivor_, and therefore the long list of references in the back. So I am only talking crocodilians (crocs, alligators, caimans and the gharial). Their growth rate is dependent on food and they can technically grow their entire lives, but the _rate of growth_ diminishes greatly as they get older. So a big croc is an old croc. A small croc may also be an old croc. So technically, the OP is right, but the grown may be negligible in a big old guy. As for there being no theoretical limit to their life span - I have never heard that one before. Despite mythical old animals of more than 100 years and mythical huge ones, the research into America’s most famous old, huge alligator, ‘Old Monsurat’ shows that he was probably only about 50 years old and about 5.6m - despite rumours of much more. Reptilians lose their teeth regularly, with them being replaced by smaller teeth which grow within the tooth cavity. With alligators, these stop regrowing at about 50 years or so (this all depends on their living conditions), and hence they can no longer feed. Crocs most certainly die natural deaths of old age, and I have no doubt the same is true for other reptiles. Lynne ---
**Author:** ![Sapo](https://avatars.discourse-cdn.com/v4/letter/s/ec9cab/32.png) [@Sapo](https://boards.straightdope.com/u/Sapo)\ **Post date:** [December 19, 2006, 1:48am UTC](https://boards.straightdope.com/t/do-reptiles-keep-growing-throughout-their-entire-lives-what-about-birds/384709/5 "2006-12-19T01:48:29Z")
[http://www.nytimes.com/2006/12/12/science/12turt.html?\_r=1&ref=science&oref=slogin](http://www.nytimes.com/2006/12/12/science/12turt.html?_r=1&ref=science&oref=slogin) sorry for the unformatted link. The article is just about to pass into “paid subscription only” mode so be quick to check it out. Here is a quote of the relevant part with the names of the researchers if someone wants to find a better link to their work. > [@](#): > > Behind such biblical longevity is the turtle’s stubborn refusal to senesce — to grow old. Don’t be fooled by the wrinkles, the halting gait and the rheumy gaze. Researchers lately have been astonished to discover that in contrast to nearly every other animal studied, a turtle’s organs do not gradually break down or become less efficient over time. > > Dr. Christopher J. Raxworthy, the associate curator of herpetology at the American Museum of Natural History, says the liver, lungs and kidneys of a centenarian turtle are virtually indistinguishable from those of its teenage counterpart, a Ponce de Leonic quality that has inspired investigators to begin examining the turtle genome for novel longevity genes. > > “Turtles don’t really die of old age,” Dr. Raxworthy said. In fact, if turtles didn’t get eaten, crushed by an automobile or fall prey to a disease, he said, they might just live indefinitely ---
**Author:** ![lynne-42](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lynne-42/32/3138_2.png) [@lynne-42](https://boards.straightdope.com/u/lynne-42)\ **Post date:** [December 19, 2006, 2:50am UTC](https://boards.straightdope.com/t/do-reptiles-keep-growing-throughout-their-entire-lives-what-about-birds/384709/6 "2006-12-19T02:50:37Z")
Thank you for that, **Sapo**. Fascinating article. They certainly live to extraordinary ages, but they do die at 250 years or so. The cases quoted were not run over or killed. I don’t think he literally meant indefinitely - as if - for ever and ever. I think he meant for extraordinarily long lifespans. I don’t think that can be extrapolated to all reptiles. Lynne ---
**Author:** ![BrassyPhrase](https://avatars.discourse-cdn.com/v4/letter/b/ea666f/32.png) [@BrassyPhrase](https://boards.straightdope.com/u/BrassyPhrase)\ **Post date:** [December 19, 2006, 7:22am UTC](https://boards.straightdope.com/t/do-reptiles-keep-growing-throughout-their-entire-lives-what-about-birds/384709/7 "2006-12-19T07:22:24Z")
[QUOTE=lynne-42] As for there being no theoretical limit to their life span - I have never heard that one before. Despite mythical old animals of more than 100 years and mythical huge ones, the research into America’s most famous old, huge alligator, ‘Old Monsurat’ shows that he was probably only about 50 years old and about 5.6m - despite rumours of much more. Lynne [/QUOTE] Where can I get more info on this? Damn, Google has spoiled me–if I don’t get a hit in the first five, then NO INFORMATION EXISTS! (heh!) I tried the alternate spellings it suggested as well, just in case. And I was beaten to the NYT turtle article reference–which _was_ pretty dang interesting. Made me want to be a turtle nerd! ---
**Author:** ![Sapo](https://avatars.discourse-cdn.com/v4/letter/s/ec9cab/32.png) [@Sapo](https://boards.straightdope.com/u/Sapo)\ **Post date:** [December 19, 2006, 12:26pm UTC](https://boards.straightdope.com/t/do-reptiles-keep-growing-throughout-their-entire-lives-what-about-birds/384709/8 "2006-12-19T12:26:15Z")
if you get a pet turtle, be mean to them. That way they won’t miss you so much when you die before they do. ---
**Author:** ![Sage\_Rat](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/sage_rat/32/399_2.png) [@Sage\_Rat](https://boards.straightdope.com/u/Sage_Rat)\ **Post date:** [December 19, 2006, 2:06pm UTC](https://boards.straightdope.com/t/do-reptiles-keep-growing-throughout-their-entire-lives-what-about-birds/384709/9 "2006-12-19T14:06:35Z")
[QUOTE=lynne-42] I know little about birds, except that there are certainly maximum sizes and identification is often linked to size, so these maximums are consistent for adult of a species. [/QUOTE] Humans shrink though, after we reach our maximum size. Assuming that you need to “grow” just to maintain the same size, or that the growth may be so insignificant, it seems entirely plausible that a bird could _technically_ be considered to still be growing, without it being very obvious, or even particularly measurable. ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [December 19, 2006, 2:33pm UTC](https://boards.straightdope.com/t/do-reptiles-keep-growing-throughout-their-entire-lives-what-about-birds/384709/10 "2006-12-19T14:33:31Z")
[QUOTE=Sage Rat] it seems entirely plausible that a bird could _technically_ be considered to still be growing, without it being very obvious, or even particularly measurable. [/QUOTE] Indeed in the wild, where things seem to die or get eaten before they reach any kind of ripe age, it seems possible that the standard size is just a statistical effect. Of course birds aren’t indefinitely scalable (if they want to retain the power of flight) - the amount of growth I’m talking about here is maybe a 5 % increase in body size over the last six months. It might not sound as though that would be noticeable, but in the case of my pet bird, he can no longer fit through a gap that was merely a tight fit a few months ago. ---
**Author:** ![astro](https://avatars.discourse-cdn.com/v4/letter/a/9dc877/32.png) [@astro](https://boards.straightdope.com/u/astro)\ **Post date:** [December 19, 2006, 2:39pm UTC](https://boards.straightdope.com/t/do-reptiles-keep-growing-throughout-their-entire-lives-what-about-birds/384709/11 "2006-12-19T14:39:52Z")
[This herpetologist’s MB post](http://dml.cmnh.org/1997Jan/msg00242.html) seems to say “no” to the notion of immortal reptiles and would explain why even turtles (granted really, really old turtles) eventually die of old age. I really have no clue what “Hayflick limit” or “SV40 transformation” means. > [@](#): > > — Begin Message — > To: [GSP1954@aol.com](mailto:GSP1954@aol.com) > Subject: Re: Size and longevity > From: Joe Daniel \ > Date: Thu, 16 Jan 1997 17:15:21 -0600 > References: \<199701161838.NAA11326@juliet.ucs.indiana.edu\> > [GSP1954@aol.com](mailto:GSP1954@aol.com) wrote: > > \> It appears that animals that grow through life - reptiles, some crustaceans, > \> etc - literally do not age physiologically. They are perpetual juveniles with > \> immortal cells, strong immune systems, good nerves and vigorous muscle > \> contractions. In other words, because they never stop growing, they never get > \> around to aging! Animals that cease growth - such as we poor humans - have > \> cells that are literally programmed to die after about 100 cell divisions (as > \> it happens you can read about this in my new book BEYOND HUMANITY, in the > \> section that discusses why human immortality probably is possible with the > \> right genetic engineering maybe with a little nanotech thrown in - and why it > \> is not the best idea). So we keel over no matter what. Reptiles, however, > \> always die from something bad happening to them. You know, starvation, > \> disease, accident, predation. Example, the oldest known animal was a captive > \> tortoise that died at age 152+ (twas a baby when caught) from an accident. It > \> appears statistically extremely improbable that any given reptile will live > \> beyond 100-150 years, maybe less in the dangerous wild. Which is a good > \> thing, because if the old folks stay around they will compete with their own > \> young too much. > > This isn’t really true. Reptile cells do age. Admittedly, they do last about > as long as ours but senesce they do. How do I know? Besides the papers published by Sam Goldstein and Elena Moerman, I’ve grown tortoise fibroblasts myself. They obey their own Hayflick limit just like every other nonimmortalized fibroblast. Perhaps you could give me some references, but I’ve never seen immortal reptile cells that weren’t artificially made that way by SV40 tansformation. > > Joe Daniel ---
**Author:** ![Sal\_Ammoniac](https://avatars.discourse-cdn.com/v4/letter/s/8dc957/32.png) [@Sal\_Ammoniac](https://boards.straightdope.com/u/Sal_Ammoniac)\ **Post date:** [December 19, 2006, 3:38pm UTC](https://boards.straightdope.com/t/do-reptiles-keep-growing-throughout-their-entire-lives-what-about-birds/384709/12 "2006-12-19T15:38:48Z")
The thing about budgies (and parrots) is that they live to be quite old. If your budgie continued to grow even a little bit (your 5% in six months, say), it could end up the size of a turkey. ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [December 19, 2006, 3:58pm UTC](https://boards.straightdope.com/t/do-reptiles-keep-growing-throughout-their-entire-lives-what-about-birds/384709/13 "2006-12-19T15:58:56Z")
Well… there’s the strange thing - he’s a small bird anyway; most of the birds in the aviary he came from are twice his size - which made me wonder if they’re just _bigger because they’re older_. It may not be that at all - it might be that they are show standard breeding stock and the offspring being sold as pets are the ‘culls’ - i.e. the ones that are never going to make good show birds. ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [December 19, 2006, 4:00pm UTC](https://boards.straightdope.com/t/do-reptiles-keep-growing-throughout-their-entire-lives-what-about-birds/384709/14 "2006-12-19T16:00:09Z")
Also… turkey-size may never happen if the growth were to continue, but at an ever-decreasing rate. ---
**Author:** ![Sal\_Ammoniac](https://avatars.discourse-cdn.com/v4/letter/s/8dc957/32.png) [@Sal\_Ammoniac](https://boards.straightdope.com/u/Sal_Ammoniac)\ **Post date:** [December 19, 2006, 4:23pm UTC](https://boards.straightdope.com/t/do-reptiles-keep-growing-throughout-their-entire-lives-what-about-birds/384709/15 "2006-12-19T16:23:52Z")
Well, unusually for me, I did a bit of math. I reckoned that if in the first six months, your five-inch bird grew 5%, in the second six months grew 4.75%, etc., carrying the calculation forward with the growth rate steadily diminishing to zero, then after 11 years, your parakeet would be over eight inches tall. It seems unlikely to me. Parakeets have been kept as pets for a long time, and if this growth had been observed before now, we’d know about it. ---
**Author:** ![Darwins\_Finch](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/darwins_finch/32/20304_2.png) [@Darwins\_Finch](https://boards.straightdope.com/u/Darwins_Finch)\ **Post date:** [December 19, 2006, 6:10pm UTC](https://boards.straightdope.com/t/do-reptiles-keep-growing-throughout-their-entire-lives-what-about-birds/384709/16 "2006-12-19T18:10:21Z")
From [here](http://www.senescence.info/nature.html), regarding reptile growth and senescence: > [@](#): > > Like amphibians, reptiles not show “big bang” reproduction (Patnaik, 1994), and tend to show a lower incidence and intensity of aging than most mammals (Finch, 1990, pp. 219-221; de Magalhaes and Toussaint, 2002). Some reptilian species show signs of aging comparable to that seen in mammals (Majhi et al., 2000; Jena et al., 2002; Olsson and Shine, 2002). While some species show signs of reproductive senescence, oogenesis in adulthood has been reported for others. Unlike some animals, like many fishes, that grow continuously throughout their lives, reptiles tend to grow slower at older ages, in both short- and long-lived species. Like amphibians, most reptiles feature polyphyodonty (Patnaik, 1994). Several species of reptiles, particularly turtles, appear to feature negligible senescence and very long lifespans. Blanding’s turtle (Emydoidea blandingii) has been shown to increase survival and reproductive output over a 75-year period (Congdon et al., 2001), and similar results have been reported for the eastern box turtle (Terrapene carolina; Fig. 5A; Miller, 2001). Alligators showed some reproductive senescence but the results are inconclusive (Finch, 1990, pp. 144-145). Marion’s tortoise (Geochelone gigantia) is claimed to have lifespans over 150 years, which is uncertain but possible since some captive turtles live up to 70 years. An increase in mortality was found in wild Geochelone but extrinsic factors might be involved. The Galapagos tortoise (Geochelone nigra) also appears to be long-lived with a possible record longevity of 177 years (Fig. 5B). Despite some species having a sexual peak, reproductive senescence has not been convincingly reported for reptilians, though further studies are necessary. Some snakes might also escape senescence; many species actually lay more eggs as they increase in size with age; for instance, Natrix maura ceases to grow but animals can live beyond that point with no detectable increases in mortality. Although conclusive opinions can hardly be formed, it appears that reptilians and amphibians show a less intense aging phenotype with many species failing to show a characteristic maximum lifespan. And, regarding birds, from the same site: > [@](#): > > Like amphibians and reptiles, birds are not known to exhibit rapid senescence or semelparity. Certain species show a definitive trend of accelerating mortality with age, being galliforms the most extreme example (Ottinger, 2001). Other species, however, show very low increases in mortality with age and some long-lived species show an increase in parenting success with age. Species with very long lifespans and little signs of reproductive senescence are common: the Andean condor (Vultur gryphus) appears to be the longest lived bird capable of living up to 75 years; no senescence has been reported but detailed studies are lacking. Other species such as Fulmarus glacialis and Sterna paradisaea also show little signs senescence (Gosden, 1996, pp. 55-56). From mathematical calculations it has been proposed that these long-lived birds must show some mortality increase, apart perhaps from condors. Comparing birds with mammals, some authors suggest that birds age slower than mammals (Holmes and Austad, 1995; Holmes et al., 2001; Holmes and Ottinger, 2003). Nonetheless, there are no verified reports of birds with negligible senescence or animals living over 100 years. **Birds do not have continuous growth.** Bolding mine. As for anecdotal data, I have a cockatiel that I’ve had for nigh on 9 years now, and he is exactly the same size as he was when I first got him. ---
**Author:** ![lynne-42](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lynne-42/32/3138_2.png) [@lynne-42](https://boards.straightdope.com/u/lynne-42)\ **Post date:** [December 20, 2006, 8:20am UTC](https://boards.straightdope.com/t/do-reptiles-keep-growing-throughout-their-entire-lives-what-about-birds/384709/17 "2006-12-20T08:20:05Z")
[QUOTE=BrassyPhrase] Where can I get more info on this? Damn, Google has spoiled me–if I don’t get a hit in the first five, then NO INFORMATION EXISTS! (heh!) I tried the alternate spellings it suggested as well, just in case. [/QUOTE] My book won’t be released in the US until July next year, so I’m not doing a sell! Try Leonard Lee Rue III, "Alligators and Crocodiles’ p. 85. There are many claims of larger ones, and the actual largest is debated, it depends what degree of authenticaton you require. The best site on anything crocodilian is [www.crocodilian.com](http://www.crocodilian.com/) Lynne ---
**Author:** ![FRDE](https://avatars.discourse-cdn.com/v4/letter/f/e68b1a/32.png) [@FRDE](https://boards.straightdope.com/u/FRDE)\ **Post date:** [December 20, 2006, 10:04am UTC](https://boards.straightdope.com/t/do-reptiles-keep-growing-throughout-their-entire-lives-what-about-birds/384709/18 "2006-12-20T10:04:28Z")
Mangetout, maybe your budgie is getting fat :-} I’ve seen stuff fairly recently, that birds live a lot longer than people expected, findings from ringing birds were surprizing. A quick dig just came up with slow sites. ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [December 20, 2006, 10:16am UTC](https://boards.straightdope.com/t/do-reptiles-keep-growing-throughout-their-entire-lives-what-about-birds/384709/19 "2006-12-20T10:16:33Z")
[QUOTE=FRDE] Mangetout, maybe your budgie is getting fat :-} [/QUOTE] It’s possible that it is just a combination of weight gain and a few more feathers, or thicker ones. I thought I had detected an increase in height too though, but this isn’t as easy to accurately measure as is weight and general size. He’s only just over a year old - I’m not even sure whether that means he’s outside the age range for normal juvenile growth. Of course, it’s also possible that there is some kind of disorder such as an overactive gland… ---
**Author:** ![FRDE](https://avatars.discourse-cdn.com/v4/letter/f/e68b1a/32.png) [@FRDE](https://boards.straightdope.com/u/FRDE)\ **Post date:** [December 20, 2006, 10:42am UTC](https://boards.straightdope.com/t/do-reptiles-keep-growing-throughout-their-entire-lives-what-about-birds/384709/20 "2006-12-20T10:42:39Z")
[QUOTE=Mangetout] It’s possible that it is just a combination of weight gain and a few more feathers, or thicker ones. I thought I had detected an increase in height too though, but this isn’t as easy to accurately measure as is weight and general size. He’s only just over a year old - I’m not even sure whether that means he’s outside the age range for normal juvenile growth. Of course, it’s also possible that there is some kind of disorder such as an overactive gland… [/QUOTE] Are you sure he is a ‘he’ ? I gather sexing young chickens is quite a skill, with a budgie one probably needs a microscope. [Next page](https://boards.straightdope.com/t/do-reptiles-keep-growing-throughout-their-entire-lives-what-about-birds/384709.md?page=2)