It's the one thing every creature with a long, thin tail wants...
A longer, thinner tail!
And once you've done that, well... let's go ahead and make it just a little bit longer... little more... more... how about a lot longer... bit more... Too much? Nah... bit more...
Video: Charles Lam
Basically, Antenna Rays have completely cornered the "long tail" market.
There's actually not a whole lot known about them. Their alternative name, Long-tailed River Stingray, gives you a lot of the basics. They belong to the genus Plesiotrygon and are found in the Amazon and other South American rivers where they go about munching on worms and crustaceans.
Only two species are currently known and you can aptly call them the big one and the little one. Not that the big one is all that big.
P. nana is the smaller and it's thought to reach about 25 cm (10 in) across at most. The better known P. iwamae can get to 65 cm (26 in) across and, such is the way with stingrays, about the same length. Oh! Unless you include the mysteriously extravagant and delicate tail, of course. Then it's more like 2 metres (6.5 ft) long!
Antenna Rays seem to mate during the rainy season and it takes a gestation period of as much as 8 months before females give birth to a maximum of just 4 pups, usually less. I guess those incredible tails take a lot of work!