Haddon's sea anemone

Stichodactyla haddoni, widely known as Haddon's sea anemone or Carpet Anemone, is a distinctive species of sea anemone in the family Stichodactylidae, primarily found across the tropical and subtropical waters of the Indo-Pacific region, stretching from 🇲🇺 Mauritius to 🇫🇯 Fiji and the Ryukyu Islands (🇯🇵 Japan) of southern 🇯🇵 Japan to 🇦🇺 Australia.

With its striking appearance, Stichodactyla haddoni features a folded oral disc that spans between 50 and 80 centimeters (20 to 31 inches) in diameter, and a tentacle-free central area measuring 1 to 2 centimeters (0.4 to 0.8 inches) across. Its tentacles, which have rounded tips and varying colors such as green, yellow, gray, and occasionally blue or pink, exhibit a pattern of alternating short and long lengths around the disc. The column, the part of the anemone visible when it is contracted, is covered with small non-sticky bumps called verrucae, usually matching the column's color and blending seamlessly with it. The overall tentacle hue tends to be yellowish or tan.

Stichodactyla haddoni thrives on sandy ocean floors, and while it is a passive organism, it obtains nourishment primarily through two methods. It engages in a symbiotic relationship with zooxanthellae, microscopic algae that perform photosynthesis in its tissues. Additionally, it captures prey such as small invertebrates and juvenile fish using its tentacles, which deliver immobilizing toxins like SHTX.

Haddon's sea anemone is also known for its mutualistic relationships with several species of clownfish, including Amphiprion akindynos, Amphiprion chrysogaster, Amphiprion chrysopterus, Amphiprion clarkii, Amphiprion polymnus, and Amphiprion sebae. Juvenile Dascyllus trimaculatus are also known to associate with the anemone. Other marine creatures, like the porcelain crab Neopetrolisthes maculatus and shrimp from the genus Periclimenes as well as Thor amboinensis, often interact with Stichodactyla haddoni, although these relationships are usually commensal rather than beneficial to the anemone.

In 🇹🇭 Thailand, Stichodactyla haddoni is intriguingly nicknamed "Hed lub," translating to "bob up and down mushroom," due to its resemblance to a mushroom. On islands like Ko Samui and Ko Pha-ngan, the anemone is occasionally used in a local dish called Kaeng kua, despite being a protected species in the country.