Rare Purple Acorn Worms in the Deep-Sea of the Marianas!
During our first official ROV Hercules dive of the 2026 season, we traveled over 3,700 meters (12,000+ feet) beneath the waves to explore an unknown seamount east of the Mariana Trench. While exploring the slopes - some of the oldest seafloor on the planet - we spotted not one but TWO striking purple acorn worms (class Enteropneusta, Family Torquaratoridae). These benthic invertebrates are the only known hermaphrodites of the phylum Hemichordata.
Unlike other wormy members of the phylum, they rely less on their proboscises for sucking up sediment. Instead, the acorn worm uses bilateral lateral lips to collect and filter biological particulate matter from the sediment. Looking a bit like ears, these lips inspired the genus name Yoda, from the much-loved pop culture character. The trails of acorn worms are frequently spotted on the seafloor as the worms continuously expel spiral casts of digested material in the sediment. What a thrilling sighting of these lesser-known deep-sea dwellers in an area no humans have ever seen before!
Ocean Exploration Trust's NA179 and NA180 Exploration of Deep-Sea Habitats in the Mariana Islands expeditions are supported by NOAA Ocean Exploration via the Ocean Exploration Cooperative Institute, with additional support from the Bureau of Ocean Energy Management for AUV Sentry’s participation.
Deep-Sea Habitats in the Mariana Islands I
This expedition will focus on exploring the Mariana region- one of the ocean's most tectonically and volcanically dynamic locations, marked by the Earth’s deepest oceanic trench, some of the most active submarine volcanoes, and some of the oldest seafloor on the planet.
