Though their serpentine locomotion might be off-putting to some, when roundworms do the deed, they're surprisingly graceful. A simple animal with only about neurons, C. But its reproductive system is quite complex. While the worm's mating behavior could be described as a reflex, "this is not a blind machine," Emmons said. The worm comes in two sexual forms: male and female-hermaphrodite. The hermaphrodite form has two X chromosomes, and it bears most of the organs of a typical female: ovaries, a uterus and a vulva. During her larval stage, she develops sperm first and then eggs, which are fertilized by the sperm in a structure called the spermatheca before making their way to the uterus.

They also live in herds and perform feats of engineering that have baffled scientists for decades. This week, an earthworm called Dave has been exciting the British public. That is because Dave has been measured at 16in 40cm long, making him and her we'll explain that later the longest earthworm recorded in the UK.

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