A small crustacean acts as the sea's bees

Date:
July 28, 2022
Source:
CNRS

The crucial role of insects in the pollination of flowering plants is well known, but algal fertilization assisted by marine animals was hitherto deemed non-existent. A team led by a CNRS researcher from the Franco-Chilean Evolutionary Biology and Ecology of Algae research unit at Roscoff Marine Station (CNRS / Sorbonne University / Pontificia Universidad Católica de Chile / Universidad Austral de Chile) has discovered that small crustaceans known as idoteas contribute to the reproductive cycle of the red alga Gracilaria gracilis. The scientists' findings are published in Science (29 July 2022). They suggest that animal-mediated fertilization is much older than once thought.

Are sea animals involved in the reproductive cycle of algae, like pollinating insects on dry land? Dispersal of the male gametes, or spermatia, of red algae generally relies on water movement, and up until now, scientists did not recognize the role played by animals.

Yet an international team led by Myriam Valero, a CNRS scientist affiliated with the Evolutionary Biology and Ecology of Algae research unit (CNRS / Pontificia Universidad Católica de Chile / Sorbonne University / Universidad Austral de Chile) and Roscoff Marine Station (CNRS / Sorbonne University)1, has revealed that tiny marine creatures called idoteas act as 'sea bees' for the red alga Gracilaria gracilis.

Idoteas contribute to the fertilization of G. gracilis as they swim amid these algae. The surfaces of the male algae are dotted with reproductive structures that produce spermatia coated with mucilage, a sticky substance. As an idotea passes by, the spermatia adhere to its cuticle and are then deposited on the thalli of any female alga the crustacean comes into contact, thus helping G. gracilis reproduction.

More:
https://www.sciencedaily.com/releases/2022/07/220728142957.htm

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Is this pillbug-like organism a pollinator of the sea?
Small crustacean could be a rare example of animal-aided pollination in the ocean
28 JUL 20222:45 PMBYERIK STOKSTAD



The crustacean Idotea balthica can fertilize female red algae by transporting spermlike cells.
WILFRIED THOMAS/BIOLOGICAL STATION OF ROSCOFF/CNRS/SU/ROSCOFF, FRANCE

The birds and the bees are expert pollinators on land, but how does this vital task happen in the sea? A decade ago, scientists discovered small marine worms and crustaceans transport pollen between flowering seagrass, and now another research team has found a possible new pollinator: a slender crustacean called an isopod that swims between red algae with its sperm cells stuck to its body, fertilizing the plant as it grazes.

“It’s a really exciting piece of work,” says Susan Kalisz, a plant evolutionary ecologist at the University of Tennessee, Knoxville, who was not involved with the research. That’s because most plant fertilization in the ocean takes place without animal help, with eggs and sperm brought together by the sloshing of seawater. But with more sleuthing, Kalisz says, researchers might turn up further examples of animal-assisted pollination.

Myriam Valero, a population geneticist at CNRS, the French national research agency, has been studying the genetics of the red alga Gracilaria gracilis for many years in the tidepools of Europe. The reproduction of the plant is unusual. In many marine organisms, males and females release their sperm and egg cells to mix in the water. In the case of Gracilaria, however, things are more complicated: The female alga doesn’t release its egg cells, but keeps them inside funnel-shaped filaments. The male’s sperm must somehow reach them—even though the cells lack tails to help them swim.

Valero noticed the algae were often covered with crawling isopods, 4-centimeter-long crustaceans that look a bit like slender pillbugs. She wondered whether the particular species, Idotea balthica, might be transporting the sperm from male to female algae. Under the microscope, it was clear that tiny sperm stick to the isopod. “We began to think maybe it can have the same role as a pollinator,” she says.

More:
https://www.science.org/content/article/pillbug-like-organism-pollinator-sea