A FASTER-PACED WORLD - CONTRASTS IN BIOVOLUME AND LIFE-PROCESS RATES IN CYCLOSTOME (CLASS STENOLAEMATA) AND CHEILOSTOME (CLASS GYMNOLAEMATA) BRYOZOANS

Zooids of cheilostome bryozoans are on average substantially more robu st than are zooids of cyclostome bryozoans. The differences include gr eater number, length, and cross-sectional area of tentacles, plus a mo re extensively developed funiculus. Median values for mouth size and c ilia-generated feeding current velocity are greater for cheilostomes t han for cyclostomes so that cheilostomes have the potential for greate r intake of nutrient energy per unit time, which may explain their app arently higher growth rates. For unit area of substrate occupied, the Cheilostomata (Class Gymnolaemata; members of the post-Paleozoic fauna ) contain greater biomass and apparently generate greater energy flow than do the Cyclostomata, which are the only extant order of the Class Stenolaemata (characteristic of the Paleozoic fauna).