The body plan of the cyphonautes larva
of bryozoans prevents high clearance rates: comparison with the pluteus and a growth model.
First, morphological and behavioral studies show that a cyphonautes larva bears a pyriform organ that secretes a thin mucous sheet that aids the larva in locomotion and attaches the larva temporarily to the substratum (Stricker 1988).
Therefore, flow direction - rather than the velocity gradient or boundary shear stress - appears to be more important in directing the cyphonautes larva's exploratory locomotion.
Membranipora membranacea (Superfamily Membraniporoidea): Feeding Cyphonautes Larva
Versatile ciliary behaviour in capture of particles by the bryozoan cyphonautes larva
. Acta Zool.
An analogous situation has been described for the cyphonautes larva
of bryozoans, in which ciliated band length does not increase proportionately to body volume during growth and development (McEdward and Strathmann, 1987).
A second hypothesis is that particles are halted by a sieve formed by stationary laterofrontal cilia, as observed for the cyphonautes larva
of bryozoans (Strathmann and McEdward, 1986).