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ILLUSTRATES: Alexandre de Souza
QUESTION: Tarsila Santos Rodrigues, Recife, PE
These annelid animals are hermaphrodites, that is, they have both sexes – therefore, they are capable of fertilizing and being fertilized at the same time. Even so, the earthworm cannot fertilize itself: it needs a partner. The process lasts about three hours, generates between three and 20 “chicks” and can happen several times a year. As each worm lives, on average, four years, it is easy to understand why these animals multiply so quickly in your backyard.
1. The worms position themselves in the opposite direction: the “head” of one is at the height of the “tail” of the other. The clitellum, a discolored ring in the anterior region of the body, releases a mucus that helps to fix them in this position. There, each injects sperm into a specific organ of the other: a pouch called spermatheca.
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two. After they separate, the clitellum begins to create a type of shell, similar to the cocoon of butterflies. The worm begins to walk backwards, dragging its clitellum along the ground to move the cocoon along its body until it reaches its head. On this “path”, he passes through the female opening, where he collects the eggs, and takes them to the spermathecae.
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earthworms – eggs
3. When the eggs (female gametes) meet the sperm (male gametes), the magic moment happens: fertilization! The worm keeps moving until it takes the cocoon out of its body. It is left in the soil and will protect the fertilized eggs as they develop, without any supervision from the “parents”. The development of the young in the cocoon can last from two weeks to three months, depending on the species. When they leave there, the young already have an adult body.
CONSULTANCY Paulo César de Paiva, specialist in annelids at the Department of Zoology at UFRJ