On land, turtles are legendary slowpokes but over time, they're living proof that, as the saying goes, slow and steady wins the race. For more than 200 million years, these amazing creatures have plodded along in much the same form we know them today. In fact, turtles existed before dinosaurs ruled the Earth and endured after those prehistoric beasts went extinct. Differences between guys and girls often aren't apparent until they reach maturity and vary among species. But among the five most popular North American pet species, sometimes you have to look closely.
The top shell, or carapace, of an adult red-eared slider, so named for the distinguishing stripe behind each eye, ranges between 5 and 8 inches in length, with females slightly larger than males. According to the Gulf Coast Turtle and Tortoise Society of Houston, Texas, the tails of mature males are noticeably longer and thicker than those of females. Other distinguishing characteristics: When you turn over red sliders and other turtles over, you'll see a gap between the carapace and the lower shell, or plastron, where the animal's limbs extend from. The position of the anal opening, or cloaca, differs between the sexes. In males, it extends beyond the rear edge of the carapace, but in females, it's typically at or just under the carapace. Males also have longer front toenails, which they vibrate against the faces of females during courtship rituals, according to the Gulf Coast Turtle and Tortoise Society.
Western Painted Turtles
Differences between male and female Western painted turtles are similar to those of red-eared sliders. The tails of males are longer and wider at the base than those of females. On males, cloacal openings typically extend past the end of the carapace while in females, they're closer to the base of the tail. And like red-eared sliders, male painted turtles have much longer front claws than females, which they also use in courtship.
Eastern Box Turtles
All six subspecies of box turtle native to North America share similar characteristics, although Eastern box turtles are the most common pets. Box turtles have higher-domed carapaces than other species and when feeling threatened, they can retract their head, limbs and tails into their shells and slam both layers closed, like a locked box, thereby thwarting predators. One way to distinguish males from females at a glance is to look at their eyes, says the Smithsonian National Zoological Park. In males, the irises are red and in females, they're yellowish brown. Males also have longer, thicker tails. These turtles range in length from about 4 to 8 inches, with males slightly larger than females, and can live more than 100 years.
Common Map Turtles
One way to recognize the stripe-skinned common map turtle, found from southern Canada to central Alabama and west to Oklahoma, is by the small yellow spot behind each eye. When trying to determine the gender of this species, look to the head and overall size, says Georgia Wildlife. Males reach a carapace length of only about 6 inches while females attain almost twice that size. Females' heads are also much broader than those of males. Juvenile and adult male map turtles also have spines on the posterior part of their carapace, which females lack.
North American Wood Turtles
Wood turtles, found mainly in the northeastern United States and adjoining regions of Canada, are a protected species almost everywhere, so any in pet stores will be captive-bred. Males are about 8 1/2 to 9 1/2 inches long and females about a third smaller. The plastrons of males are slightly concave compared to those of females, which are more flat; the tails of males are also longer and thicker. One extraordinary hunting strategy practiced by some wood turtle populations is known as "worm-stomping," notes West Virginia's Department of Natural Resources. After seeking out areas likely to support healthy populations of earthworms, the turtles beat rhythmically on the ground with their front feet, luring worms to the surface -- whereupon the turtles promptly make a meal of them.