What Deep-Sea Corals Eat: Marine Snow, Plankton, and Symbiosis

Unlike shallow-water corals that rely on photosynthetic symbionts, deep-sea corals (below 200 m, often 500–2,000+ m) live in perpetual darkness and employ diverse feeding strategies:

1. Marine Snow Capture

Organic detritus (dead plankton, fecal pellets, mucus) sinks from surface waters. Corals use mucus nets, ciliated tentacles, or sticky polyps to trap this "snow."

2. Active Predation on Zooplankton

Many extend tentacles armed with nematocysts (stinging cells) to capture copepods, amphipods, and other drifting crustaceans.

3. Detritus and Sediment Ingestion

Some ingest organic-rich sediment directly or via symbiotic bacteria that break down refractory compounds.

4. Chemosynthetic Symbioses

At cold seeps and hydrothermal vents, certain corals host bacteria that oxidize methane or hydrogen sulfide, providing organic carbon to the host.

5. Dissolved Organic Matter (DOM) Uptake

Emerging evidence suggests some corals absorb dissolved organics directly across their tissue.

Feeding mode varies by species, depth, and local food supply. This versatility allows corals to thrive in food-poor abyssal environments, forming complex reefs that support diverse communities.