unless you had it from the time he was born, you can't tell. counting the rings on it's shell DOES NOT work.
A general age guess can be gained by simply looking at the size of the turtle. Yellow bellied and red ear sliders will reach approximately the size of a dinner plate when full grown.
A yellow back turtle or yellow-bellied slider is an aquatic terrapin which has evolved to live in warm waters. There is no definitive way in determining how old it is and the rings on its shell are not conclusive in gauging its years of age.
The upper shell is brown and black, often with yellow stripes. The skin is an olive green color with patches of yellow down the neck and legs. The bottom shell is mostly yellow with green spots along the edges. Adult males grow darker as they age. Yellow-bellied sliders are sometimes confused with Easter River Cooters, who also have yellow stripes on the neck and yellow under the sides, but they lack the olive green color of their skin.
Both names refer to the same animal. In America terrapins, tortoises and turtles are all referred to as turtles. This has caused some confusion in the hobby and some pet/reptile shops here in the UK also call terrapins turtles. The peninsular cooter (also a terrapin) looks almost identical to the yellow bellied terrapin. Hope this helps.
by ya face
Turtles begin to get restless and try to escape their tank when they are almost ready to lay eggs. They also may begin to make digging motions with their back legs.
Masculine turtles usually:have (slightly) concave plastronhave a bigger tailhave much longer nailsare smaller in comparison - 5 - 8 inches shell full size, compared to 8 - 13 inches for females
Use a thermometer ! You, as a keeper, should know the temperature ranges suitable for a RES.
A yellow bellied sap sucker!
For Red Eared Turtles a female has short nails and a male as long sharp nails.
Male or Female Turtle???if you need to know a boy or a girl you look at the belly...a male is flat and a girl is kinda sacky...you know to keep the eggs in. BY THE WAY i got this from a library book!!! no liein. well look at the nails,if girl the claws are short,if boy the nails are long,also the male popps his head out more then girls,and girls tails are usasuly more tucked and the boys have more thicker tails too!!!!
to see if a red eared slider is a boy or girl, look at the claws and tail. if they r long it is a girl. if they r short it is a boy. I know because I have two of them