Syllids are most frequent in shallow water associated with hard substrata
and are especially abundant on coral reefs (Kohn & Lloyd, 1973) . Members
of the subfamily Exogoninae are also well represented in bathyal and abyssal
areas . All syllids have eversible, cylindrical, often armed pharynges, followed
by strongly muscular pumping structures called proventricles . The pharyngeal
armature is most commonly in the form of a single, dagger-shaped tooth, but
a series of large or small teeth encircling the pharyngeal opening may also
be present (e .g ., Trypanosyllis, Eusyllis) .
Syllids generally are considered non-tubicolous . Forms associated with
hydroids, however, often build mucous tubes along the colonies (Hughes,
1975 ; Fauchald and Jumars, pers . obs .).
Members of the subfamily Autolytinae feed largely on hydroids (Okada,
1928 ; Hamond, 1969 ; Hughes, 1975) each species is more or less a specialist
on a single kind of hydroid or on a few related kinds . Other syllids feed on