What 2 animals do not walk backwards, and why does a duck's quack, not produce an echo?

Question

What 2 animals do not walk backwards, and why does a duck's quack, not produce an echo?

Answer 1

kangaroos,i know,don't walk backwards....i don't know anymore animals....

ducks have echos only it can only be heard FAINTLY...something with pitch or something....hard to explain

Answer 2

a duck's quack does echo, just very, very faintly. Something to do with the frequency or pitch of it. As for the other part....... what? lol

Answer 3

Emus and Kangaroos are unable to walk backwards. Duck's quack echos, but it is very hard ot hear.

Answer 4

Emus and kangaroos cannot walk backwards.

http://www.planetozkids.com/oban/animals...

Duck's quack do echo...Recent study has revealed that duck's quack definitely echoes but not  as noticeably.

A quack is a fading sound. It has gradual decay , so it's hard to tell the difference between the actual quack and echo.

http://www.snopes.com/critters/wild/duck...