Insects like bees have long been known to help plants reproduce by spreading pollen from one plant to another. Now, however, a similar ‘fix’ has been discovered in the underwater world, involving red algae and small crustaceans . The research was led by doctoral student Emma Lavaut, from France’s Sorbonne University, and population geneticist Myriam Valero from the CNRS (Centre National de la Recherche Scientifique).
small but useful
A tiny mealybug-like crustacean appears to help fertilize red algae in rock pools, much like a bee pollinates flowers. This suggests that such behavior is more common in the oceans than we thought, and animal-mediated pollination may even have evolved there.
This discovery is the first known example of animal-driven “pollination” in algae. Both red algae and crustaceans belong to groups much older than land plants, raising the possibility that a form of pollination first evolved in the ocean, hundreds of millions earlier than originally thought.
During the life cycle of algae, there may be individuals that are male or female. It was already known that water currents can transport spermatia, the seaweed version of sperm, from males to the reproductive organs of nearby female algae. Each fertilization event generates a bulb-shaped structure that is visible to the naked eye, called a cystocarp, in the female algae.
In the new study, Myriam Valero, a population geneticist at Sorbonne University in Paris, and her colleagues were studying the genetics and mating of G. gracilis. After collecting seaweed samples and storing them in laboratory tanks, the team continued to notice hundreds of small, oblong crustaceans in the tanks. This discovery and the algal sperm’s similarity to pollen led the team to wonder if the crustaceans help “pollinate” the algae.
What percentage of gamete dispersal is done by crustaceans has yet to be determined , as underwater currents definitely play a role. But this finding suggests that insect-style plant pollination may have evolved from a process that began in the sea.
Referencia: E. Lavaut et al. Pollinators of the sea: A discovery of animal-mediated fertilization in seaweed. Science. Vol. 377, July 29, 2022, p. 528. doi: 10.1126/science.abo6661.