以 + Food + 为 + 食
食 (shí) means "to eat" or "to feed on" and is a classical or literary verb for consuming food. In modern Chinese, it often appears in set phrases like 以…为食 (to feed on) rather than being used alone.
大熊猫以竹子为食。
dà xióngmāo yǐ zhúzi wéi shí.
Giant pandas feed on bamboo.
这种鸟主要以昆虫为食。
zhè zhǒng niǎo zhǔyào yǐ kūnchóng wéi shí.
This type of bird mainly feeds on insects.
鲸鱼以小鱼和浮游生物为食。
jīngyú yǐ xiǎo yú hé fúyóu shēngwù wéi shí.
Whales feed on small fish and plankton.