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How do earthworms reproduce using the clitellum?

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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.*

Earthworms are hermaphroditic invertebrates that utilize the clitellum—a swollen, girdle-like organ—to facilitate reproduction.12

During mating, two earthworms exchange sperm, which is stored in specialized sacs. Following this exchange, the clitellum secretes a mucous tube that slides along the worm's body. As the tube moves, it collects the worm's own eggs and the stored sperm received from its partner.12

As the worm continues to move forward, it eventually slips out of this mucous tube, which then closes to form a lemon-shaped cocoon. Fertilization occurs within this cocoon, which acts as a protective, nest-like environment where the young earthworms develop before hatching.12