animal tails

[kabuto]

just wondering about this.

why does animals have tails?

what is it for? and why dont we have tail?

[mith]

It can be prehensile(used as a hand).
It can be for balance.
It can be for fighting...

[Khaiy]

We don't have them because our ancestors lost them for some reason; it could be chance, it could be that there was some disadvantage to a tail for an upright walking animal, or many other reasons. We can't be 100% sure what caused the evolutionary event that got rid of our ancestor's tails though, since we weren't around to see it.

We do still have the tail bone, which still has the shape that would support a tail, our species just doesn't have the actual tail anymore!

[kabuto]

It can be for fighting...

[kiekyon]

It can be for fighting...

think crocodile...

[Darby]

In terms of humans, the tails were long-gone by the time we came along (the apes don't have them).

Perhaps a tail helps climbing balance only up to a certain-sized animal. That would make it tough to explain big cats, though... It's possible that the ancestral ape was a ground-dweller (the fossil record is pretty spotty on that lineage).

Keep in mind, too, that only vertebrates officially have tails (postanal tails, at least), and these were originally for swimming.

[rach]

i wish i had a tail...

[madnewt]

We lost our tails when our ancestors descended from the trees as there was no need for them. Monkeys use their tails for gripping and balance but for life on the ground, they became redundant. With the evolution of the thumb, our hands became better designed for gripping and making things than a tail could ever be and they could used for fighting as well. Man can not move fast enough under our own propulsion for a tail to be anything other than a liability.

All cats can move fast enough to warrant a tail for balance and it also helps express the temperament and status of the animal like in dogs.

[AstusAleator]

If you go back to chordate ancestry, where postanal tails were derived, they evolved to help in swimming. Then in amphibians they served to help swim and balance. With reptiles, again it helped balance (and in some helped swim and fight).
Think about that big T-Rex, what would happen if it didn't have a tail and wanted to lean over and catch something.