"How early the role of pou-iv in mechanoreceptor differentiation emerged in animal evolution remains unresolved, and requires comparative data from placozoans and sponges, which are wanting." "Our results indicate that the role for pou-iv in mechanoreceptor development is broadly conserved across Cnidaria and Bilateria," the researchers wrote in their paper. To trace the gene back even further, however, will require data from other phyla with earlier divergence points. Together, the researchers said, the results suggest that pou-iv played a role in the development of mechanosensory cells in the common ancestor between Cnidaria and Bilateria. Sea anemones may not have kidneys, but sensing fluid flow would be a useful ability for marine animals. In addition, knocking out pou-iv in the anemones significantly suppressed a gene very similar to the one which makes polycystin 1 that is found in vertebrates, where it is required for the sensing of fluid flow in kidneys. In mammals, pou-iv is required for the development of hair cells we know this because mice that have had pou-iv knocked out are deaf. These cells have bundles of finger-like organelles called stereocilia that sense mechanical stimuli namely, the vibrations we hear as sound. In humans and other vertebrates, the sensory receptors of the auditory system are called hair cells. The outer surface of the column has a loose covering of mucus. There is a fairly distinct division between the scapus, the main part of the column, and the capitulum, the part just below the crown of tentacles. but it also informs us that the building blocks of our sense of hearing have ancient evolutionary roots dating back hundreds of millions of years into the Precambrian," said biologist Nagayasu Nakanishi of the University of Arkansas. The starlet sea anemone has a bulbous basal end and a contracting column that ranges in length from less than 2 to 6 cm (0.8 to 2.4 in). The starlet sea anemone Nematostella vectensis is emerging as a model for animal development and evolution because the phylum Cnidaria is one of the earliest. "This study is exciting because it not only opened a new field of research into how mechanosensation develops and functions in a sea anemone. The discovery of the gene's role in the starlet sea anemone suggests that it was present in their common ancestor and likely played a role in sensory development then, too. Cnidaria, the phylum to which sea anemones belong, is the closest relative to Bilateria, animals with bilateral symmetry such as humans, diverging from their last common ancestor that lived around 748 to 604 million years ago.
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