‘The Lynx Nudibranch’
Phidiana lynceus (Lynx Nudibranch) on Spondylus americanus oyster
Music, Video, and Aquarium
2010 Coral Morphologic

Last week we spent a moment making eyes with the oyster (Spondylus americanus). This week we’ll spend a moment with a diverse community of animals and plants that have colonized the upper shell of the very same oyster. Towards the left of the frame is a small colony of flower-like animals known as hydroids. Hydroids are most closely related to jellyfish, but instead remain attached to the reef their whole lives (unlike a jellyfish). But, like the jellyfish, hydroids can pack a powerful stinging punch. The brown, daisy-like creatures seen growing here on the oysters’s back are one such type of hydroid, Myrionema amboinense. This hydroid species derives its brown coloration from the symbiotic zooxanthellae (dinoflagellate ‘algae’) stored in its tissues. The ability to gain nutrition from both prey capture and photosynthesis, allows these hydroids to grow and colonize quickly. The sting from these hydroids is considerably more powerful than that of most corals. The gray, lumpy knobs on the back of the oyster shell are zoanthid polyps, close cousins of the sea anemones. However, these zoanthids are no match against the powerful sting of the hydroids. The zoanthids have all but acknowledged defeat by the encroaching stingers by simply closing up; effectively handing over control of the oyster shell to the hydroids.

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