What is a darker contor line usaly every fifth line?

Index contour.

Explanation: Index contours are those elevation line which are represented by a thick or darker line. It is because if we draw every elevation with a simple line, its not so reliable. So making every fifth contour line dark helps us in reading the map elevation clearly without any difficulties.

   This is very commonly used in the maps and are separated at equal heights.

A camel can be found in the desert and also a gila monster. 
A camel has 11 toes (On each foot), long legs for travel,  long eyelashes for sand,and humps that store water. All of these features help Camels go long ways for travel. 
A gila mosters are venoumous lizards have a verey painful bite. Gila monsters latch on to their victims and eject their venom. Gila monster's diet mainly includes unborn eggs, newborn mammals (animals), and nests.