Using your links and jumping around a bit from link to link, I think I found it:Looks very much like a wild gourd.
Echinocystis lobata (wild cucumber) is probably edible. Here's the wikipedia:
Echinocystis - Wikipedia
en.wikipedia.org
Some Cucurbitaceae are toxic:
Marah (plant) - Wikipedia
en.wikipedia.org
Using your links and jumping around a bit from link to link, I think I found it:
Marah fabacea - Wikipedia
en.wikipedia.org
Not sure if I should feed it to the tortoises or not. The tuber was used by Indians to immobilize fish, but it says the leaves have been used as a vegetable. I have so many other known food items to offer them, but its a shame to let this one go to waste if its okay to feed them.