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What is the typhlosole in an earthworm intestine used for?

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annelid *The structure of polychaetes.* (Left) Free-moving polychaetes. (A) *Neanthes,* (B) *Nereis.* (Right) Tube-dwelling (sedentary) polychaetes. (C) *Amphitrite,* (D) *Sabella.*

In earthworms, the typhlosole is a longitudinal fold of the intestinal wall that projects into the digestive cavity. Its primary function is to increase the surface area of the intestine, which enhances the efficiency of nutrient absorption.12

The absorptive surfaces of the typhlosole, along with the anterior intestine, may feature a brush border to further facilitate this process. Notably, this region is specifically involved in the absorption of fats.2