Acorn Worms are a class of marine worms that were long thought to be members of the phylum Chordata, alongside all the vertebrates and such oddities as sea squirts and salps.
They’ve since been placed within a phylum of their own called Hemichordata, and the evidence now suggests they’re actually more closely related to echinoderms.
For the longest time all known Acorn Worms lived in burrows in shallow water, where they consumed detritus and went largely unnoticed.
That all changed when we acquired the technology to take a really good look at the bottom of deep sea environments. In turns there’s entire family of Acorn Worms down there! They’re much more colourful and conspicuous than their shallow-water kin, and spend their time crawling around eating the ooze beneath them.
They don’t burrow, but they do use a bubble of mucus to rise up from the seabed and drift on the currents to find new feeding grounds.
That’s why I love the deep sea. It’s a place where worms can fly!
…Images: Moorea Biocode/R. Lutz/David Shale