Aprocean-1

my_crobes

Hydra viridissima (The Green Hydra) is a freshwater relative of jellyfish and corals in the phylum Cnidaria. This Hydra is green because it has an obligate symbiotic relationship with an algae called Chlorella strain A99.

This is an obligate symbiosis because the Chlorella can no longer survive on their own. The algae has lost its ability to uptake nitrogen naturally from its environment, and instead receives its nitrogen from the hydra via the amino acid glutamine. Each Chlorella is stored in its own compartment called a “symbiosome” and the algae is directly passed down from each generation of the Hydra.

This is a mutualistic symbiosis because the algae give the Hydra energy and fixed carbon from photosynthesis, and the Hydra gives the algae its source of nitrogen as well as protection from the environment. Having this symbiosis means that the green Hydra can withstand much longer periods of food scarcity than its non-photosynthetic counterparts.

Source:

Mayuko Hamada, Katja Schröder, Jay Bathia, Ulrich Kürn, Sebastian Fraune, Mariia Khalturina, Konstantin Khalturin, Chuya Shinzato, Nori Satoh, Thomas CG Bosch (2018) Metabolic co-dependence drives the evolutionarily ancient Hydra–Chlorella symbiosis eLife 7:e35122

https://doi.org/10.7554/eLife.35122