In my personal opinion, the greatest coming-of-age story on Earth does not take place in a Dickens novel or a Disney movie, but rather in a white fish at the bottom of the Pacific Ocean.

Whether you like it or not, parasites are everywhere, lurking seen and unseen in almost every ecosystem on Earth. Nearly every free-living organism on the planet, including me and you, can host one or more species of parasite. Yet parasites are often overlooked, or studied only for the threats they pose to human health, says Armand Kuris, a parasite ecologist at the University of California at Santa Barbara. For half a century, Kuris has been studying how parasites affect the ecosystems they occupy and how much influence they can hold over their environment. As an example, Kuris describes an estuary near the town of Carpinteria, a short drive from his office. “There’s a few elephants’ worth of trematode tissue in that salt marsh,” Kuris says, and I imagine a Miyazaki-esque elephant formed by millions of writhing worms. “You could see them from the freeway if they weren’t all in the snails.”

Of course, a Santa Barbara beach is more or less heaven on Earth for any living thing, human or parasitic worm. Life in the abyssal deep sea is generally less halcyon, dominated by vast slopes and plains where your chances of encountering anything living are slim. But hydrothermal vents are like the Santa Barbaras of the abyss, peaceful respites where life can be abundant and flourishing. In other words, it’s a great place to be a parasitic worm.