Heteractis magnifica
A solitary sentinel of the reef flat, guarding its territory and its clownfish.
Heteractis magnifica, commonly known as the magnificent sea anemone, is a species of sea anemone in the family Actiniidae, described by Ernst Haeckel in 1880. It is a large, sessile cnidarian whose column and tentacle crown can reach considerable diameter, and it is distributed across the tropical Indo-Pacific—from the Red Sea and East African coast, through the Indian Ocean, to the western Pacific (WoRMS species record; Wikipedia § Distribution). In reef ecology it occupies a keystone role as the obligate host for multiple species of clownfish (subfamily Amphiprioninae), forming one of the most studied mutualisms in marine biology (Wikipedia § Symbiosis).
- Common name
- Magnificent sea anemone
- Family
- Actiniidae
- Distribution
- Red Sea, Indian Ocean, western Pacific (Indo-Pacific)
- Typical habitat
- Shallow reef flats, lagoons, outer reef slopes
- Substrate preference
- Rock, coral rubble
- Symbiotic partners
- Multiple Amphiprioninae (clownfish) species
- Locomotion
- Sessile (pedal disc attached)
Lore & Background
Per the WoRMS taxonomic record and the Wikipedia § Morphology section, Heteractis magnifica is distinguished from its congeners H. crispa and H. aurora by its relatively broad, smooth column and the dense, short tentacles that give the crown a thick, brush-like appearance. The oral disc is typically pale, contrasting with a column that ranges from cream to deep maroon depending on the population and light exposure. The anemone is strictly solitary: a single individual anchors its pedal disc to a rock or a piece of coral rubble and defends a small territory, expelling other anemones and non-symbiotic intruders with its nematocyst-laden tentacles (Wikipedia § Behavior).
Reader's Guide
Sighting Record 1 — Location: Ras Mohammed, Red Sea, Egypt. Depth: 2 m, reef flat. Substrate: flat basalt slab with scattered coral rubble. Sediment context: fine biogenic sand with fragments of broken Acropora and a single dead Pocillopora colony. Season: March (dry, high-visibility). Record type: single specimen, three established clownfish (Amphiprion ocellaris) in crown. Status: unremarkable, consistent with range.
Sighting Record 2 — Location: Malé Atoll, Maldives. Depth: 4 m, lagoon edge. Substrate: packed coral sand with a single large boulder; anemone attached to boulder's up-facing surface. Sediment context: dense rubble of Porites and Favia, occasional live Pocillopora. Season: November (wet, moderate swell). Record type: single specimen, no clownfish present. Status: first-time record for this survey team; anemone appears recently settled (column still pale, tentacles short). Flagged for follow-up.
Sighting Record 3 — Location: Heron Island, Great Barrier Reef, Australia. Depth: 1 m, intertidal pool. Substrate: live coral head (Montipora) with anemone anchored in a crevice. Sediment context: mixed sand and fine coral dust, a small population of Turbinaria algae. Season: July (winter, clear). Record type: single specimen, five clownfish (A. percula) in crown. Status: consistent with range; no dispute. Note: pool dries at extreme low tide; anemone retracts fully, a behaviour noted in the Wikipedia § Intertidal tolerance section.
Did You Know?
- Heteractis magnifica is strictly solitary; two anemones of the same species will not share a substrate, and a newcomer will be expelled or will relocate (Wikipedia § Behavior).
- The anemone's distribution spans roughly 60° of longitude, from the Red Sea to Fiji, yet it is absent from the deep mesophotic zone in every surveyed record (WoRMS range; Wikipedia § Habitat).
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