PLEASE HELP This lizard species is one of the few social lizards that have family groups and will defend their babies and territory against members of another group.

Tutara

Explanation:

The social structure of tuatara is similar to that of iguanian lizards (iguanas, anoles, agamas, chameleons, and others) in that territorial defense and courtship behaviours are established through body display and colour changes. They also are defensive of their eggs, along with being defensive.

the sphincter muscles at the end of the digestive tract is the anus.

i'm thinking (a) to keep sand in place; ////////////

explanation: a sand fence or sandbreak, like a snow fence, is used to force windblown, drifting sand to accumulate in a desired place. sand fences are employed to control erosion, sand dune stabilization, keep sand off roadways, and to recruit new material in desert areas.