My Google searches seemed to avail no results. My question is: What is the largest living species in the class Polychaeta?

That's about it. I understand that there will be few accessible weights for these worms so length will suffice.


According to the Smithsonian:

The longest of all known polychaetes was found in Port Jackson, Australia. It was a member of the family Eunicidae, consisted of approximately 1,500 segments and was nearly 6 meters long when alive.

The Eunicidae consist of numerous species (including the super cool bobbit worm), many of which get fairly large.

enter image description here

Though, typically 3 m in considered quite large for worms in this group (e.g., see Uchida et al. 2009 for a description of a 3 m long Eunice aphroditois).

Polychaetes & Allies: The Southern Synthesis also suggests that members of Eucinidae can reach 6 m in length. From p. 94 of this report from the Australian Biological Resources Study:

Eunicids have many segments and may attain a length of up to 6m...

...Eunicids range from less than 10cm to 6m in length, and consists of up to 1500 segments (Fauchald 1992a).

Supposedly, according to Schulze 2011:

The Australian museum even holds a specimen that reportedly was nearly 6 m long when collected (Fauchald 1992 and pers. comm.)

Salazar-Vallejo et al. (2011) also cite evidence of 3+ m long polychaetes in the genus Eunice as evidence that the genus is "the largest polychaete species and placing them among the longest benthic invertebrates."

None of these worms compare to a species of ribbon worm (phylum Nemertea) called Lineus longissimus that can reach 55 m in length! [Sources: 1, 2].


Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.