Hormonally active phytochemicals from macroalgae: A largely untapped source of ligands to deorphanize nuclear receptors in emerging marine animal models

•Hormonally active phytochemicals are mainly investigated in terrestrial ecosystems.•Animal interactions with photosynthetic organisms started in the marine environment.•Marine macroalgae are phylogenetically distant from land plants.•Hormonally active phytochemicals are present in brown and red macroalgae.•Their ecological relevance for animal nuclear receptors is still elusive.