New mouthless, gutless bone-eating worm species discovered in Gulf of Cádiz

The organism, named Osedax martini, lacks a mouth, gut, or anus, relying entirely on root-like vascular structures and symbiotic bacteria to extract nutrition from vertebrate bones deposited on the ocean floor.

Published in the Zoological Journal of the Linnean Society, the discovery was led by researchers from the National Museum of Natural Sciences (MNCN) and the Spanish Institute of Oceanography (IEO). The team identified Osedax martini at two specific locations off Cadiz: the Anastasya mud volcano at a depth of 449 metres, and the Cadiz Channel at 715 metres.

Specimens were also recorded off Girona and Murcia, confirming its range spans both Atlantic and Mediterranean waters.

To study these elusive organisms, CSIC researchers deployed specialised underwater lander platforms equipped with cow and pig bone bait at nine strategic points around the Iberian peninsula.

Once recovered, the landers revealed thriving colonies of Osedax.

Despite lacking a digestive tract, Osedax worms play a vital ecological role in deep-sea ecosystems by breaking down organic matter from fallen marine carcasses and recycling nutrients back into the food chain.

Researchers noted that Osedax martini exhibited two distinct external morphotypes, a physical variation that surprised the scientific team.

Alongside Osedax martini, the CSIC investigation identified two other previously unknown species within Spanish waters:

• Osedax emmae: Discovered at a depth of 542 metres in the El Cachucho Marine Protected Area off the Cantabrian coast.

• Osedax teoi: Located off Mazarrón in the province of Murcia at depths exceeding 1,200 metres.

The findings highlight the significant volume of hidden biodiversity that remains undiscovered across the Iberian seabed.