People accept the idea of echinoderm predation on shallow reef building corals. The voracious Crown of Thorns seastar Acanthaster planci is a familiar coral antagonist on the Great Barrier Reef, part of a natural process that may or may not be amplified by anthropogenic disturbance. Asteroid predation on deep-sea corals is more difficult to demonstrate.
Hippasteria sp. has been caught in the act feeding on deep-sea Primnoa (Krieger & Wing 2002) and Isidella octocorals (Etnoyer 2008), but brittle stars and echinoids are typically considered commensal associates. Some ophiuroids (brittlestars) are obligate commensals, “partners for life” on deep-sea Metallogorgia corals (Mosher & Watling 2009).
Something in the image above tells me this sea urchin is up to no good, but I’m having a hard time convincing others that a culprit is present. The party line is that associates brisingids (sea star, bottom image) and ophiuroids are suspension feeders. Chris Mah was non-plussed when I sent these. My fortune cookie said “one observation is not data, Grasshopper, it’s datum“. Still, you’ve got to wonder, can echinoderms have their deep-sea coral habitat and eat it, too?
Etnoyer, P. (2008). A new species of Isidella bamboo coral (Octocorallia: Alcyonacea: Isididae) from northeast Pacific Seamounts Proceedings of the Biological Society of Washington, 121 (4), 541-553 DOI: 10.2988/08-16.1
Krieger, K., & Wing, B. (2002). Megafauna associations with deepwater corals (Primnoa spp.) in the Gulf of Alaska Hydrobiologia, 471 (1/3), 83-90 DOI: 10.1023/A:1016597119297
Mosher, C., & Watling, L. (2009). Partners for life: a brittle star and its octocoral host Marine Ecology Progress Series DOI: 10.3354/meps08113