Versatile ciliary behaviour in capture of particles by the bryozoan cyphonautes larva

Cyphonautes larvae of a bryozoan, Membranipora membranacea, used several ciliary mechanisms to capture algal cells upstream from the lateral band of cilia that produces a feeding current. (1) Lateral cilia changed beat and a backcurrent occurred at the time and place that particles were retained. (2) Algal cells were sieved and held stationary at the upstream (frontal) side of a row of laterofrontal cilia that were not beating. (3) Localized extension of cilia toward the inhalant chamber, coincident with particle captures, indicated that laterofrontal cilia flick toward the inhalant chamber. These flicks may aid transport of captured particles toward the mouth. Thus my earlier report that larvae only sieve, in contrast to the adults (which have an active ciliary response) was in error. The similar ciliary bands in adult and larval bryozoans and in other lophophorates (brachiopods, and phoronids) suggest that these animals share a core repertoire of ciliary behaviours in the capture and concentration of suspended food particles.     

Redescription of Alcyonidium my till Dalyell, 1848 (Bryozoa: Gtenostomatida)

Reproduction in the ctenostomate bryozoan Alcyonidium mytili Dalyell, 1848, was studied over 2 years, revealing confusion in the literature over the diagnostic characters of the species and incorrect assumptions about the mode of reproduction. The literature is briefly reviewed and an approximate type locality from the Firth of Forth, Scotland, is identified. Alcyonidium mytili is comprehensively redescribed from material collected in the Firth of Forth and from 2 years' collections in the Daugleddau estuary, near Pembroke Dock, South Wales. Zooid and polypide dimensions and modal tentacle number (16) have been determined from large samples. Most importantly A. mytili possesses a conspicuous intertentacular organ when reproductive; is oviparous, with eggs discharged through the intertentacular organ developing into cyphonautes larvae; and has a prolonged winter reproductive period. The contrary indications in the literature are a consequence of confusion with a superficially similar but larviparous species.