The Study of Placozoa through the Ages: From Morphology to Functional Genomics

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Abstract

Placozoa (Trichoplax) — highly simplified free-living metazoans originating during the peak of marine biodiversity diversification. Placozoans are morphologically and functionally asymmetric organisms lacking muscles, a nervous system, and clear body symmetry. Despite their structural simplicity, they exhibit complex behaviors, including social interactions. Research on Placozoa and the establishment of this phylum has a long history, whichwe present here as a chronological timeline spanning from early studies of their biology and morphology to modern genomic and transcriptomic analyses. This review synthesizes recent advances in Placozoan biology and critically evaluates accumulated data. Based on this analysis, weidentify the most promising future research directions for this enigmatic group.

About the authors

D. Y. Romanova

Laboratory of Cellular Neurobiology of Learning, Institute of Higher Nervous Activity and Neurophysiology, RAS

Email: darjaromanova@gmail.com
Butlerova 5a, 117485 Moscow, Russian Federation

V. S. Kololeeva

Laboratory of Cellular Neurobiology of Learning, Institute of Higher Nervous Activity and Neurophysiology, RAS

Email: darjaromanova@gmail.com
Butlerova 5a, 117485 Moscow, Russian Federation

M. A. Nikitin

Laboratory of Cellular Neurobiology of Learning, Institute of Higher Nervous Activity and Neurophysiology, RAS; Belozersky Institute of Physicochemical Biology, Lomonosov Moscow State University

Email: darjaromanova@gmail.com
Butlerova 5a, 117485 Moscow, Russian Federation; Leninskie Gory 1/40, 119992 Moscow, Russian Federation

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