Worm Eggs Really Do Look Like Tiny Lemons
I mentioned in our earthworm dissection video that earthworm eggs look like tiny lemons. And they do! Check out the picture above of some earthworm eggs and see for yourself. There’s plenty of other fascinating things to know about earthworm reproduction, though.
Earthworms are hermaphrodites, meaning they have both male and female reproductive organs. As you might have seen in our earthworm dissection video, this means they have both a spermatic vesicle to produce sperm and spermatic receptacle to receive it. When worms reproduce, two worms line up against one another facing opposite directions. Then both worms excrete a slime tube around their bodies, formed from mucus. Then each worm receives sperm from the other worm, and both worms are fertilized.
Next, the clitellum comes into play. The clitellum is that wide band that earthworms have near their head. The clitellum produces another tube of mucus, which is then passed forward toward the anterior end of the worm. On its way, this mucus passes over the sacs containing the worm's eggs, which catch a ride by sticking to the slime. This slime tube then passes over the seminal receptacle, where the other worm's sperm is kept. The eggs thus become fertilized in the slime tube.
The worms then back out of the slime tube, which then forms a cocoon in the shape of - yes here it is - a lemon! This cocoon may have anywhere from four to twenty eggs. Earthworms reproduce quickly and increase their population exponentially; one breeding earthworm can produce 96 new baby worms in six months.