Growth and space

[marginatawhisperer]

Many years ago I had turtles besides tortoises.
A redeared terrapin stopped growth at 19 centimeters in about 100 liters of water.
Then after a while I put her in 500 liters of water. Same food and temperature. Growth then came back, and she reached 22 centimeters. I have heard similar stories.
I have never heard an explanation for this mechanism, but I accept it as a fact.
Now my question is: Has this subtle effect of space also been noticed for tortoises?
When I see the biggest Sulcatas on this forum at 500 pounds+, they seem to have a LOT of room, (and a good keeper).
It would be very interesting to know if someone has given more space to his tortoises and seen more growth.

 

[ALDABRAMAN]

Many years ago I had turtles besides tortoises.
A redeared terrapin stopped growth at 19 centimeters in about 100 liters of water.
Then after a while I put her in 500 liters of water. Same food and temperature. Growth then came back, and she reached 22 centimeters. I have heard similar stories.
I have never heard an explanation for this mechanism, but I accept it as a fact.
Now my question is: Has this subtle effect of space also been noticed for tortoises?
When I see the biggest Sulcatas on this forum at 500 pounds+, they seem to have a LOT of room, (and a good keeper).
It would be very interesting to know if someone has given more space to his tortoises and seen more growth.

* I do not think that a tortoises growth is hindered by being in a confined space, unless the small space is the main food source and lack of food contributes to inadequate or less growth. I also think that if a tortoise is kept in a small or confined space and as a result has inadequate or insufficient exercise can lead and contribute to many internal health and growth issues.

* I feel strongly that a tortoise with ample space, proper diet, and exposure to natural sunshine is a happy tortoise and has a greater chance of being at its optimal health in captivity !

 

[Madkins007]

Most of the studies done on space vs. growth show that inadequate space can stunt growth or cause deformities, and that when conditions are good, the growth resumes.

There is an upper limit to this, though. If you give the animal more space then it needs, it does not automatically grow forever, otherwise Earth would be overrun with giant reptiles!

However, tortoises practice what is called 'negligible senescence'- that means they don't really show signs of aging- including that they pretty much grow as long as they are alive. Some species, such as red-footed tortoises, sometimes produce 'giants' that are MUCH bigger than the normal population. One well-respected theory is that these are just really old examples that have just kept growing.

 

[marginatawhisperer]

This is a very fuzzy subject, but very interesting. I was perhaps under optimum tank size with my redeared 40 years ago. With fish they say growth is also limited by the cleanliness of the water. I have heard about the occasional giants. This of course could be explained by lucky old age specimens.
But the genes, or their expression, can be a possibility. More than a hundred thousand years ago in turkey a stone age settlement was found with a lot of T. graeca bones, allowing statistics, (Science dec 99, as I recall). There was over some thousands of years a size diminution in humerus diameter of about 20%.
This was not climate related. This size reduction was not assumed to be directly linear comparable to body mass, but if it is to some degree, it is substantial.
I agree with the author that this is caused by selection by man.
This happens all the time, with deer we try to counteract the effect by allowing the best to survive in modern hunting, not always succesful. The african elephant might lose its tusks, now heavy selection against that.
Tortoises in my opinion have suffered heavily from human predation over the years, favouring smaller individuals. The big ones we see on occasion might therefore have more of the original genes, worth our attention.

 

[lovelyrosepetal]

I did not know Sulcatas got to be 500 pounds! Wild.

 

[wellington]

I have no scientific studies to quote. However, if in too small of an area, then the conditions can't be correct. Fish do not grow only to the size tank they are in. However, too small of a tank will produce bad quality/enviroment, which in turn will slow the growth. I think it is the same in most species. Inadaquate space does equal poor or inadaquate conditions, which then will slow growth. Kinda like a survival mechanism. When conditions improve, so will the growth.

 

[marginatawhisperer]

Sorry about the 500 pound mistake, it is 250 pounds, I usually calculate in Kilos, intead of halving the 250 I doubled it.
The owner in this forum cannot weigh them anymore. How about a measuring tape? They are supposed to be in their late twenties.
Talking size, Pritchard 1979 in "Encyclopedia of Turtles" quotes Villiers quoting arab early medieval armchair traveller El Bekri (Al Bakri) speaking
of tortoise burrows large enough for a man to walk into. Perhaps exagerrated, and who says eventually they made them for themselves,
but I would expect sulcatas to have diminished in size over the years due to human predation.
Perhaps the present owner of the 250 Pounders will show the potential if this gene has survived, I would at least expect 300 pounds from
him in the future. Official world record I found was 107 Kilos, about 235 Pounds, so he already has that.
Reflecting over the input over the resumed growth of my old redeared, I suddenly remember that at the time she also got company in the tank,
making her more active. Good to know.

 

[Tom]

The size of the enclosure has nothing to do with how large animal is genetically programmed to get. This is a persistent myth. In fish, the large size in a small volume of poorly filtered water can lead to horrible water conditions than can stunt growth, but I have personally seen 12" oscars that were malformed and living in a 10x20" ten gallon tank. The person changes the water with bottled water two or three times a week.

I have also seen both caimans and sulcatas that grew so big in their glass enclosure that they literally could not turn around. Despicable.

The large sulcatas you speak of here on the forum are a location specific phenomenon. For whatever reason, natural selection has made the sulcatas from that region of the Sudan grow larger than sulcatas from other regions within the range. I have seen the same sort of geographical variation with green iguanas and water monitors. Probably the same phenomenon with redfoots and other reptiles.