Sleeping with the enemy: unravelling the symbiotic relationships between the scale wormNeopolynoe chondrocladiae(Annelida: Polynoidae) and its carnivorous sponge hosts

Abstract

The North Atlantic deep-water polynoid worm Neopolynoe chondrocladiae is involved in an exceptional symbiotic relationship with two hosts: the carnivorous sponges Chondrocladia robertballardi and Chondrocladia virgata. While this is an obligate symbiotic relationship, its real nature is unclear. We used a multidisciplinary approach to narrow down the type of symbiotic relationship between symbiont and hosts. Molecular connectivity analyses using COI and 16S suggest that N. chondrocladiae has high potential for dispersal, connecting sites hundreds of kilometres apart, likely aided by oceanographic currents. Microbial analyses on different anatomical parts of five Chondrocladia species suggest that the presence of the worm in C. robertballardi does not affect the microbiome of the sponge. MicroCT analysis on N. chondrocladiae show that it has dorsally oriented parapodia, which might prevent the worm from getting trapped in the sponge. A faecal pellet recovered from the worm suggests that the polynoid feeds on the crustacean prey captured by the sponge, something corroborated by our stable isotope analysis. Light and confocal microscopy images suggest that N. chondrocladiae elytra produce bioluminescence. We propose that the worm might use bioluminescence as a lure for prey (increasing the food available for both the sponge and the polynoid) and thus fuelling a mutualistic relationship.

Ramisyllis kingghidorahi n. sp., a new branching annelid from Japan

“…Aguado and et al (2015a) did not find any trace of the sponge contamination in the genome data of R. multicaudata, which together with no visual evidence of sponge tissue in the digestive tube of Ramisyllis may indicate that branching species do not feed on their host sponges. However, further studies involving more specific techniques, e.g., stable isotope and fatty acids analyses (Taboada et al, 2021) and sponge and worm microbiomes characterization (Turon et al, 2019), would be necessary for more conclusive results. The finding of highly ciliated digestive tubes, especially at the posterior ends and ani, might indicate the use of posterior ends for incorporating fluids into the digestive system.…”

On the Diversity of Phyllodocida (Annelida: Errantia), with a Focus on Glyceridae, Goniadidae, Nephtyidae, Polynoidae, Sphaerodoridae, Syllidae, and the Holoplanktonic Families

“…However, like their shallow-water relatives, most of them are benthic, many likely correspond to undescribed species, and quite a lot seem to be symbionts. Among them, new discoveries include species associated with carnivorous sponges [416,417], black corals [418], cold-water corals [419,420], holothurians [395,421], and acorn worms (https://www.youtube.com/watch?v=yrlSmxG5yZY, accessed on on 18 November 2020).…”

Investigating the diversity of bioluminescent marine worm Polycirrus (Annelida), with description of three new species from the Western Pacific

“…Despite its occurrence, there is still much that is unknown about bioluminescence in polychaetes, including how it evolved and what it means ecologically. More research is needed to better understand this phenomenon, and to do this, we need to accumulate more examples of bioluminescent polychaetes [3,5,[7][8][9][10][11][12].…”