Phylogenetic relationships and the timing of evolutionary events are essential for understanding evolution on longer time scales. Cheilostome bryozoans are a group of ubiquitous, species-rich, marine colonial organisms with an excellent fossil record but lack phylogenetic relationships inferred from molecular data. We present genome-skimmed data for 395 cheilostomes and combine these with 315 published sequences to infer relationships and the timing of key events among c. 500 cheilostome species. We find that named cheilostome genera and species are phylogenetically coherent, rendering fossil or contemporary specimens readily delimited using only skeletal morphology. Our phylogeny shows that parental care in the form of brooding evolved several times independently but was never lost in cheilostomes. Our fossil calibration, robust to varied assumptions, indicates that the cheilostome lineage and parental care therein could have Paleozoic origins, much older than the first known fossil record of cheilostomes in the Late Jurassic.

The article is devoted to individual behaviour of autozooids (mainly connected with feeding and cleaning) in 40 species and subspecies of marine bryozoans from the White Sea and the Barents Sea. We present comparative descriptions of the observations and for the first time describe some of autozooidal activities (e.g. cleaning of the colony surface by a reversal of tentacular ciliature beating, variants of testing-position, and particle capture and rejection). Non-contradictory aspects from the main hypotheses on bryozoan feeding have been used to create a model of feeding mechanism. Flicking activity in the absence of previous mechanical contact between tentacle and particle leads to the inference that polypides in some species can detect particles at some distance. The discussion deals with both normal and “spontaneous” reactions, as well as differences and similarities in autozooidal behaviour and their probable causes. Approaches to classification of the diversity of bryozoan behaviour (functional and morphological) are considered. Behavioural reactions recorded are classified using a morphological approach based on the structure (tentacular ciliature, tentacles and entire polypide) performing the reaction. We suggest that polypide protrusion and retraction might be the basis of the origin of some other individual activities. Individual autozooidal behaviour is considered to be a flexible and sensitive system of reactions in which the activities can be performed in different combinations and successions and can be switched depending on the situation.

The phylogenomic approach has largely resolved metazoan phylogeny and improved our knowledge of animal evolution based on morphology, paleontology, and embryology. Nevertheless, the placement of two major lophotrochozoan phyla, Entoprocta (Kamptozoa) and Ectoprocta (Bryozoa), remains highly controversial: Originally considered as a single group named Polyzoa (Bryozoa), they were separated on the basis of morphology. So far, each new study of lophotrochozoan evolution has still consistently proposed different phylogenetic positions for these groups. Here, we reinvestigated the placement of Entoprocta and Ectoprocta using highly complete datasets with rigorous contamination removal. Our results from maximum likelihood, Bayesian, and coalescent analyses strongly support the topology in which Entoprocta and Bryozoa form a distinct clade, placed as a sister group to all other lophotrochozoan clades: Annelida, Mollusca, Brachiopoda, Phoronida, and Nemertea. Our study favors the evolutionary scenario where Entoprocta, Cycliophora, and Bryozoa constitute one of the earliest branches among Lophotrochozoa and thus supports the Polyzoa hypothesis.