Syllidae

Syllidae, commonly known as the necklace worms, is a family of small to medium-sized polychaete worms. Syllids are distinguished from other polychaetes by the presence of a muscular region of the anterior digestive tract known as the proventricle.
Syllid worms range in size from to. Most syllids are benthic organisms that transition to a pelagic epitoke for reproduction. They are found in all regions of the ocean, from the intertidal zone to the deep sea, and are especially abundant in shallow water.
They are found in a range of habitats, moving actively on rock and sandy substrates, hiding in crevices and among seaweeds, and climbing on sponges, corals, hydrozoans, seagrasses and mangroves. They are generalist feeders. A young Syllid was one of the first worms to be found with pollen from seagrass in its stomach, making it a possible pollinator.
The proventricle, Syllid worm's most distinctive anatomical feature, allows the worm to feed by sucking due to its pumping action. It also plays a role in hormone production, and thus the worm's sexual development. The proventricle is composed of strirated muscle cells with the longest known sacromeres among animals. The proventricle is usually visible through the body wall.
Syllis ramosa was the first polychaete discovered to have a branching body plan. Later, two species of Ramisyllis were discovered to have a branching body plan.

Subfamilies

Anoplosyllinae
* Streptosyllis
** Streptosyllis bidentata
** Streptosyllis websteri
*Syllides
**Syllides benedicti
** Syllides longocirrata
Eusyllinae
* Clavisyllis
** Clavisyllis alternata Knox, 1957
** Clavisyllis tenjini Cejp, Jimi & Aguado, 2023
** Clavisyllis yongei Watson, 2009
* Eusyllis
** Eusyllis assimilis
** Eusyllis blomstrandi
** Eusyllis lamelligera
* Nudisyllis
** Nudisyllis divaricata
** Nudisyllis pulligera
* Odontosyllis
** Odontosyllis ctenostoma
** Odontosyllis enopla
** Odontosyllis fulgurans
** Odontosyllis gibba
** Odontosyllis phosphorea
* Opisthodonta
** Opisthodonta longocirrata
* Pionosyllis
** Pionosyllis compacta
** Pionosyllis serratisetosa
* Synmerosyllis
** Synmerosyllis lamelligera
Autolytinae
* Epigamia
** Epigamia alexandri
* Myrianida
** Myrianida brachycephala
** Myrianida edwarsi
** Myrianida inermis
** Myrianida langerhansi
** Myrianida pinnigera
** Myrianida prolifera
** Myrianida quinquedecimdentata
** Myrianida rubropunctata
* Proceraea
** Proceraea aurantiaca
** Proceraea cornuta
** Proceraea picta
** Proceraea prismatica
** Procerastea halleziana
** Procerastea nematodes
Exogoninae
* Brania
** Brania pusilla
* Erinaceusyllis
** Erinaceusyllis cirripapillata
** Erinaceusyllis erinaceus
** Erinaceusyllis ettiennei
** Erinaceusyllis hartmannschroederae
** Erinaceusyllis kathrynae
* Exogone
** Exogone dispar
** Exogone naidina
** Exogone verugera
* Exogonita Hartman & Fauchald, 1971
* Parapionosyllis Fauvel, 1923
* Parexogone
** Parexogone longicirris
** Parexogone hebes
* Prosphaerosyllis
** Prosphaerosyllis tetralix
* Salvatoria McIntosh, 1885
** Salvatoria clavata
** Salvatoria limbata
** Salvatoria swedmarki
* Sphaerosyllis
** Sphaerosyllis bardukaciculata
** Sphaerosyllis bulbosa
** Sphaerosyllis goorabantennata
** Sphaerosyllis georgeharrisoni
** Sphaerosyllis hystrix
** Sphaerosyllis levantina
** Sphaerosyllis pirifera
** Sphaerosyllis taylori
** Sphaerosyllis voluntariorum
Syllinae
* Syllis
**Syllis aciculigrossa
** Syllis adamantea
** Syllis albae
** Syllis albanyensis
** Syllis alosae
** Syllis alternata
** Syllis amica
** Syllis amicarmillaris
** Syllis anoculata
** Syllis antoniae
** Syllis armillaris
** Syllis augeneri
** Syllis barbata
** Syllis bella
** Syllis beneliahuae
** Syllis benguellana
** Syllis boggemanni
** Syllis botosaneanui
** Syllis brasiliensis
** Syllis breviarticulata
** Syllis brevicirrata
** Syllis brevicirris
** Syllis broomensis
** Syllis caeca
** Syllis castroviejoi
** Syllis cerina
** Syllis cirrita
** Syllis columbretensis
** Syllis compacta
** Syllis corallicola
** Syllis cornuta
** Syllis crassicirrata
** Syllis cruzi
** Syllis curticirris
** Syllis danieli
** Syllis deleoni
** Syllis edensis
** Syllis elongata
** Syllis ergeni
** Syllis erikae
** Syllis fasciata
** Syllis ferrani
** Syllis filidentata
** Syllis garciai
** Syllis gerlachi
** Syllis gerundensis
** Syllis glandulata
** Syllis glarearia
** Syllis golfonovensis
** Syllis gracilis
** Syllis guidae
** Syllis heterochaeta
** Syllis hyalina
** Syllis hyllebergi
** Syllis joaoi
** Syllis jorgei
** Syllis kabilica
** Syllis karlae
** Syllis kas
** Syllis komodoensis
** Syllis krohnii
** Syllis lagunae
** Syllis latifrons
** Syllis licheri
** Syllis limbata
** Syllis longesegmentata
** Syllis lunaris
** Syllis lutea
** Syllis luteoides
** Syllis macroceras
** Syllis macrodentata
** Syllis magdalena
** Syllis magnapalpa
** Syllis marceloi
** Syllis marugani
** Syllis maryae
** Syllis mauretanica
** Syllis mayeri
** Syllis mercedesae
** Syllis mexicana
** Syllis microoculata
** Syllis monilaris
** Syllis mytilorum
** Syllis nigra
** Syllis nigrescens
** Syllis nigricirris
** Syllis nigriscens
** Syllis nigropunctata
** Syllis notocera
** Syllis nuchalis
** Syllis obscura
** Syllis onkylochaeta
** Syllis ortizi
** Syllis parapari
** Syllis parturiens
** Syllis pectinans
** Syllis picta
** Syllis pigmentata
** Syllis pilosa
** Syllis pontxioi
** Syllis profunda
** Syllis prolifera
** Syllis prolixa
** Syllis pseudoarmillaris
** Syllis pulvinata
** Syllis quadrifasciata
** Syllis quaternaria
** Syllis ramosa
** Syllis riojai
** Syllis robertianae
** Syllis rosea
** Syllis rubicunda
** Syllis rudolphi
** Syllis schulzi
** Syllis sclerolaema
** Syllis setoensis
** Syllis sol
** Syllis stenura
** Syllis tamarae
** Syllis tiedemanni
** Syllis torquata
** Syllis tripantu
** Syllis truncata
** Syllis tyrrhena
** Syllis umbricolor
** Syllis unzima
** Syllis valida
** Syllis variegata
** Syllis villenai
** Syllis violacea
** Syllis vittata
** Syllis vivipara
** Syllis warrnamboolensis
** Syllis westheidei
** Syllis yallingupensis
** Syllis ypsiloides
* Ramisyllis
** Ramisyllis multicaudata
** ''Ramisyllis kingghidorahi''