For a long time it was thought that underwater pollination occurs through water streams. But new research has found that an isopod circulates under the sea, such as a tiny bee, that helps pollinate plants.
These idotheas – the name given to the bees of the seas – add to a small and recent body of research showing that animal-mediated pollination is not unique to terrestrial plants as previously thought.
“The long-held belief that there is no animal-mediated pollination in the sea contradicts recent findings in seagrass and motivates research of other marine phyla,” the authors of a new paper published in the journal Science wrote. The researchers realized that red algae could be good candidates for pollination, as the male gametes cannot move on their own.
Until now, it was thought that seagrasses and seaweeds were fertilized with the help of water currents that could sweep male gametes and deliver them to the female reproductive organs of plants.
A group of experiments involving red algae showed that the isopod species Idotea balhica is common among red algae (Gracilaria gracilis) and their presence significantly increases fertilization. By closely examining the isopods, they were able to confirm the link, finding that their bodies sometimes collect spermatium from seaweed, such as pollen that clings to a bee, and that the Idoteas can then travel over the female plants and transmit them to the necessary reproductive parts.
It seems that the isopod-seaweed duo may represent a reciprocal relationship. Algae benefit from pollination aid, while Idoteas enjoy shelter and a rich diatom food choice.
In addition to adding another invertebrate to the pollinator list, the research offers interesting implications for the evolution of animal-mediated pollination. The form of pollination appears to have evolved independently in both terrestrial and marine environments, but research is still ongoing as to whether it began in the sea before moving onto land.
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