Colonial sea squirt & blue-green algae

Didemnum molle (colonial sea squirt) & Procloron (blue-green algae)

This colonial sea squirt is clustered on branches of dead coral and contains a minute blue-green algae (Procloron) living in its body cavity in a symbiotic partnership, each of which cannot survive apart. The algae, which can be seen in the large openings, uses sunlight to photosynthesise, providing the sea squirt with an extra energy source and greatly benefiting its capacity to grow rapidly. In return, the algae receives the nutrients from the waste products of the sea squirt to help it thrive inside its tissues. Interesting chemicals have been discovered from the algae, but because it cannot live outside its sea squirt host in an artificial culture it is likely that these unique chemicals are made by both partners in symbiosis, and not by any single partner.

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