Recently here there was a thread about giant turtles. One poster linked to this article: Can Turtles Live Forever?
So what’s the deal? Can these guys live forever, assuming they don’t get run over, eaten, starve or succumb to infection?
Um, no, no animal can live forever. Turtles just have really long lifespans.
So do elephants, for that matter, but elephants don’t live forever, either.
Sexually reproducing life forms die. Eventually. Asexual life forms, such as amoeba keep dividing and the “original” keeps splitting into indistinguishable halves over and over, and are theoretically capable of “immortality”. Turtles are sexual (now there’s a boring porn tape) and die eventually. It should be noted, however, that some American snapping turtles have been killed (for soup) and musket balls and bullets from ancient wars have been found to indicate that they were shot when adults during the civil war. There are tortises in zoos more than 150 years old, but how much older, we don’t know.
Big snappers will walk around for a while after you cut the head off. You have to just hang em up and wait for the blood to all drain out. It’s been said that the head will still bite after it’s been removed, but I’ve never seen that happen.
You bet your sweet ass I am.
Oh, never mind.
It should be noted that, per the linked article, the implication of immortality comes from the fact that certain turtle species don’t senesce (physically deteriorate as a result of age). It should also be noted that even if a turtle does not age (or at least, doesn’t show its age), odds are pretty darned low of it living to see the end of the world. “Nature red in tooth and claw”, and all that (and even though many turtles don’t have much in the way of enemies, death through accident is still a very real possibility). And even for the ones in zoos, some illness or another is still likely to occur sooner or later.
The biggest obstacle to determining lifespan in turtles is the simple fact that not many studies have been conducted in this area. If you do a simple Google search on “turtle lifespan”, you’ll get lots of hits for various species wherein the lifespan is “estimated” or “unknown”.
I seem to remember from high school biology that there were certain animals, some type of shellfish was used as an example I think, that don’t experience natural death, but that die out all the same due to accident or disease or whatever. Do I remember correctly, and is this along the same line?
I think life span is determined by the tellureme (sp?) a sort of cap on the end of the dna strand that loses a portion of its length each time the dna is disassembled and recombined–i.e. each time the cell divides or replicates itself. the shorter your tellureme, the less tightly bound your dna is and the more likely parts of it will fall into disrepair. your average dna is set up to replicate about seven times after a cell life of around seven years, which is why people over 50 appear to be falling apart at the seams, why cancer is an old-folks disease generally, why heart disease and cancer have taken over for childhood illnesses as the major causes of death in the last century. Reptiles appear to be set up differently. We were descended from dinosaurs. reptiles preceded the dinosaurs and have much more primitive workings. Most reptiles will grow in size forever until killed by starvation or defeat in battle (or being hunted to death by us upstart mammals). I don’t believe there is a set life span for any reptile. They take on the temperature of their surrounding environment, so their metabolism is very slow. A meal will last a croc or a turtle or a snake for months. Anacondas have been found as long as 50 feet long. At that stage, it probably becomes more difficult to find small prey, so they will begin to snack on human babies, chickens, livestock, and whatnot, which makes them a pest. Humans who might have ignored them will then hunt them down and kill them, which limits the anaconda’s size and age. I don’t know if the reptile’s natural longevity extends to their predecessors–the amphibians–but I’ve read reports of live frogs being found in sedimentary rock that is very old. Life span seems to be a mammalian innovation.
It’s “telomere”. You can read more about turtle telomeres here (pdf article).
Not really. See linked article.
I was (in my finch guise, anyway). Everyone else, no: mammals are a completely separate lineage from dinosaurs or even reptiles in general.
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See article.
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Amphibians are a separate lineage form reptiles.
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Nope. It’s an innovation commonly associated with sexual reproduction in general.
I think that certain bacteria have turtles beat for longevity.
The Discover article discusses this problem, suggesting that the very thing that’s so interesting is itself the biggest obstacle to studying it. In other words, if you’ve got an animal that could (theoretically) live for hundreds of years, how does a human with a 70-year lifespan (only 50 of which could reasonably be spent doing legitimate research) study it? (Quite ironic, no? And I mean “ironic” in the actual sense of the word.)
The guy in the article is getting pretty close to his pull date, and is fretting that nobody seems willing to step in and carry his research torch for another 50 years, which is what it would take in this field. Scientists are only human, so it’s understandable why people wouldn’t want to work their whole lives on something they’d just have to hand off to somebody else, even if the ultimate repercussions could potentially be that important. Better to study mice or fruit flies, where you can can dozens of generations in a single year.
umm…actually one of the derived characteristics of reptiles is Determinate Growth…so…there you have it…
Are you sure about this? AFAIK mammals are descended from reptiles. I seem to remember reading that mammals are descended from a reptile that was closely related to and simlair to dinosaurs. The picture with the article was one of those dinosaur-like creatures with a big bony protusion on it’s back that looked a bit like the pipes of a church organ.
PSstt! Shows what you know.
I have it on good authority that the pope declared himself immortal!
Fuck, I thought the title was “are turtles immoral or what?” Cruisy terrapin action???
Yes, I am sure about this (well, as sure as one can be given the evidence available). Mammals and reptiles share a common amniote (egg-laying) ancestor; however, amniotes diverged into two main lineages: the Synapsids (which eventually led to mammals) and the Sauropsids (which eventually led to reptiles, and much later, birds).
The “dinosaur-like creatures” to which you refer were Therapsids (aka, “mammal-like reptiles”), which were advanced Synapsids. The church-organ-pipe-sporting fellows were critters like Dimetrodon, a Sphenacodontid (a group which shares a common ancestor with Therapsids).
I see where my confusion arise now, so the mammals ancestors where simlair to reptiles, but they weren’t reptiles.
To clarify a little bit, traditionally the ancestors of mammals were classified as ‘reptiles.’ However, under present classification schemes they are not. (And under present classification the term ‘reptile’ doesn’t have any real scientific meaning, since crocodiles are more closely related to birds than they are to turtles.)
The scientific definition of a ‘reptile’ is “the most recent common ancestor of extant turtles and saurians, and all of its descendants”. Using this definition, birds are reptiles. Here’s a great webpage on this stuff: http://tolweb.org/tree/eukaryotes/animals/chordata/amniote_lichen/Amniote_phylogeny.html