Their flattened body resists the relentless pull of the current. Black larvae. Their specialized mouthparts filter out the tiny particles of food, as they race by them.

How to analyze this sentence. Especially, " as they race by them". I cannot understand it. Does it mean the black larvae run so fast when they filter out the food? But in the film, the black larvae did not move at all, the current is powerful.

Question

Their flattened body resists the relentless pull of the current. Black larvae. Their specialized mouthparts filter out the tiny particles of food, as they race by them.

How to analyze this sentence. Especially, " as they race by them". I cannot understand it. Does it mean the black larvae run so fast when they filter out the food? But in the film, the black larvae did not move at all, the current is powerful.

Answer

Hi, the phrase " as they race by them" is referring to the many particles of food (they) moving through the mouth part quickly (race by them).

You can think of it literally as in " The girl raced by on her bicycle." or in this context where something is rapidly moving through something else.

Another example sentence can be as follow, "The strong magnet catches falling aluminum shavings as they quickly race through the vacuum."