EPOW - Ecology Picture of the Week

Explanation:  In parts of Zambia they are called "flat dogs" for their resemblance to unfortunate dogs caught sleeping in the road.  But pet them not.  At extremes, Nile crocodiles can reach nearly 6 m (20 feet) and 1000 kg (2200 lbs).  

Nile crocs have tails with two raised dorsal shields, as shown in the above photo. Adults eat fish, mammals, and birds, and only rarely the occasional careless tourist.  

One of only 23 species of order Crocodylia, Nile crocs are vestiges of the archosaurs that once dominated for over 150 million years.  They continue to dominate local rivers and pools when not persecuted by humans.  They are an integral part of the ecosystem, forming and maintaining waterholes that attract many aquatic and riparian plants, birds, mammals, and many other forms of life.  In The Gambia, crocodile pools are sacred sites as well as tourist attractions.  

Nile croc hiding among Ipomoea, an aquatic Morning Glory, in a pond kept filled by the croc's digging.  The croc also plays a role in dispersing the plant among pools.

If you can get close enough, you can recognize Nile crocodiles also by their fourth mandibular tooth, visible when the jaw is closed (this tooth is hidden in a socket in alligators), as shown in the photo to the left.

The eyes and valved nostrils are located on the top of the head (as shown at right), facilitating its ambush behavior from murky waters.