State Reptile Perhaps the most common of turtles, the painted turtle (Chysemys picta) owes its status to the efforts of a group of southwest Michigan schoolchildren. Michigan's newest state symbol was adopted by Public Act 281 of 1995.
Painted turtles are birghtly marked. They have a smooth shell about 10 to 18 cm long. The turtle has a relatively flat upper shell with red and yellow markings on a black or greenish brown background. The male and female grow at a similar rate to become 85mm long (female) and 130 mm long (male). The growth rate, for both male and female, is rapid during the first several years of the of their lives. These turtles are described as a small to medium sized reptile. At ages 7 years, for the female, and 3 years, for the male, the painted turtles are expected to be at their maturity levels. Their shell acts as protection, but since the ribs are fused to the shell, the turtle cannot expand its chest to breathe but must force air in and out of the lungs by alternately contracting the flank and shoulder muscles.
Painted turtles feed mainly on plants, small animals, and some carrion. They also feed on insects. Lacking teeth, the turtle jaw has tough, horny plates for gripping food.
In the early summer the female lays 4 to 15 oval, soft-shelled eggs, in a flask-shaped hole. The breeding season lasts from late spring to early summer. The sex of the turtle is determined during a critical phase of embryogenesis according to the incubation temperature. These temperature-dependent reptiles lack sex chromosomes. Low temperatures during incubation produce males and high temperatures produce females. Hatchlings have two threshold temperatures, 27 to 32 C and 22C. These thresholds may be important to some northern or woodland populations. Mating begins after hibernation and before feeding begins when the water temperatures are still low. Fall mating may also occur. Temperature is a major environmental cue for the regulation of the seasonal gonadal cycle, but the thermal dependence of the reproductive system differs markedly for the two sexes. The availability of water in the nests is more important than temperature in influencing survival, metabolism, and growth of the embryos.
Painted turtles bask in large groups on logs, fallen trees, and other objects. The sunning helps rid them of parasitic leeches. In many areas the turtles hibernate during the winter months. Their body size is correlated with many danger. The hatchling behavior of these turtles,which consists of movements rather than sounds, is behavior that provides a defense mechinism against predation since they are born in water and are in danger of being eaten by fish when first hatched. Sound perception is poor in turtles. Compensating for poor hearing is a good sense of smell and color vision.
Painted turtles like to live in freshwater that is quiet, shallow, and thickly planted with mud on the bottom.
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