to eat, or to sing, or to vomit into the mouths of their children
It prompts the parent bird to feed them.
They open their mouths on land, and led birds eat the food on their teeth. Hope this helps.
Innate.
they get birds to clean there teeth and skin
Crocodile and Hippos because when they open their mouths the birds will peck all off the bacteria and leftovers.
They normally lie with their mouths partly open, and the local birds pick off any bits of flesh from the teeth.
Crocodiles are often seen on the beach, looking like they are asleep, with their mouths open. What they are doing is basking, they keep their mouths open to regulate their body temperature. People sweat, dogs and cats pant, and crocodiles open their mouths :)
eels must open and cloth their mouths constantly in order to circulate water over their gills
Birds use their tongues to taste, they use their beaks/ mouths to drink.
for food
No.
they open their mouths and eat.