Hints： barren the Namib wedge-snouted lizard propulsion monopolise sap-sucking

In this barren sea of sand,it's harder for larger animals to find enough to eat.You've got to be a real specialist,like the Namib sand snake.By sidewinding,it can swim its way up the dunes.But in such an open arena,ambush is tricky,it's speed that counts.The wedge-snouted lizard can afford to be blase.It has a secret weapon,rocket propulsion.Then it's under the sand as fast as you can,the best place to escape predators and the sun. Here in the Namib,shelter is sparse.What little there is,is fiercely protected.Colonies of dune ants monopolise the tough Namib grasses.Though aggressive to most invaders,the ants do tolerate the presence of small sap-sucking bugs which they get to milk for precious sugary water.

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