Scientific American introduces us to the bees of the sea, newly observed tiny crustaceans that pollinate seaweed like bees do flowers on land:
For the red seaweed Gracilaria gracilis, which grows in scraggly clumps, this is a particular problem. Its male gametes, or spermatia, lack flexible flagella to propel them through the water. “Without the ability to swim, the sperm needs to navigate its way to the female plants in some other way,” says Myriam Valero, an ecologist at the French National Center for Scientific Research.
Scientists have long thought that the seaweed’s spermatia simply drift wherever the current takes them, with only a slim chance of landing on a female seaweed’s reproductive organ. But in a study published on Thursday in Science, Valero and her colleagues discovered that this seaweed takes a page out of the flowering plant playbook by using a “pollinator”—in this case, the species Idotea balthica, a type of buglike crustacean called an isopod—to do the fertilization for them. This is the first recorded example of an alga practicing an aquatic equivalent to pollination.
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As isopods scuttle along a male seaweed stalk, they are bombarded by spermatia, which are coated in a tacky, mucuslike substance. Like a powder-coated bee spreading pollen from plant to plant, isopods spread spermatia throughout a tide pool as they travel between seaweed clumps. In exchange for their role as fertility nurses, the isopods use the seaweed for shelter and feast on a buffet of smaller algae stuck to the stalks.
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You can read more of Valero’s research here, in Science.