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Octocoral Guaiagorgia

Octocoral assemblages have a fundamental ecological role as a habitat that provides a complex three-dimensional structure to support high biodiversity. The octocoral Guaiagorgia sp. is found abundantly in Hong Kong's western waters but not elsewhere in other parts of the Hong Kong marine environment. What is Guaiagorgia? What is so special about it? Let’s hop on and explore with us. Follow Coral Academy and stay tuned!

Funded by: Marine Ecology Enhancement Fund

柳珊瑚小分隊 Guaiagorgia team

大家好！我哋係來自中文大學珊瑚學院嘅FYP學生，Alice同Anna今年我哋研究室收到改善海洋生態基金嘅資助，研究一種香港搵到但世界少見嘅柳珊瑚 — Guaiagorgia 。Alice會研究佢哋嘅繁殖，而Anna就會研究佢哋承受壓力嘅能力。

Hi everyone! This is Alice and Anna and we are the final year project students in Coral Academy Lab, The Chinese University of Hong Kong. This year our lab received funding support from the Marine Ecology Enhancement Fund (MEEF) to look into a gorgonian coral, Guaiagorgia, which can be commonly found in some sites in Hong Kong but rarely in the world. Alice will investigate their reproductive biology, while Anna will study their environmental tolerance.

咩係八放珊瑚？What is Octocoral？

你應該有聽過珊瑚，咁你又知唔知珊瑚可按觸手數目分為兩大類？珊瑚蟲的觸手數目為六或其倍數的分類為「六放珊瑚亞網」(Hexacorallia)；有八隻觸手則為「八放珊瑚亞網」(Octocorallia)。六放珊瑚嘅成員包括石珊瑚同黑珊瑚，八放珊瑚嘅成員就包括軟珊瑚、柳珊瑚同海筆。而我哋研究嘅𝘎𝘶𝘢𝘪𝘢𝘨𝘰𝘳𝘨𝘪𝘢就係柳珊瑚嘅其中一個屬(Genus)。

Do you know that corals are divided into two groups? Corals with 6 or multiples of 6 tentacles in each polyp belongs to subclass Hexacorallia, and corals with 8 tentacles in each polyp belongs to subclass Octocorallia. Hard corals and black corals are hexacorals, while soft corals, gorgonian and sea fans are all octocorals. The coral we are studying, Guaiagorgia, is a genus of gorgonians.

咩係八放珊瑚？（續）What is Octocoral (Con't)

八放珊瑚係濾食性動物，會捉水入面嘅浮游生物嚟食同石珊瑚唔同，八放珊瑚無外在嘅碳酸鈣骨骼，亦都唔會組成珊瑚礁。

Many octocorals are filter feeders and feed on plankton. Unlike hard corals, octocorals do not possess external calcium carbonate skeleton, nor form coral reefs.

Guaiagorgia 係邊度搵到？Where to find them?

根據目前文獻所記，𝘎𝘶𝘢𝘪𝘢𝘨𝘰𝘳𝘨𝘪𝘢可以係香港西面同大嶼山北面一帶嘅海域搵到。過往調查發現，𝘎𝘶𝘢𝘪𝘢𝘨𝘰𝘳𝘨𝘪𝘢係機場附近、大磨刀洲、馬灣同青衣一帶生長。佢地比起其他珊瑚更加適應香港西面嘅水文環境同鹽度變化，因而成為咗主要嘅物種。希望日後會有更多嘅生態調查，俾我哋知多啲𝘎𝘶𝘢𝘪𝘢𝘨𝘰𝘳𝘨𝘪𝘢係香港嘅分佈啦。

According to the present literature review, 𝘎𝘶𝘢𝘪𝘢𝘨𝘰𝘳𝘨𝘪𝘢 is abundant in western Hong Kong water and Northern Lantau Island. Previous surveys show that Guaiagorgia sp. colonies can also be found near Hong Kong International Airport, Tai Mo To, Ma Wan, and Tsing Yi. They adapt to Hong Kong western water and salinity change better than other corals and become dominant. Hopefully, we will learn more about their distribution as there is more ecological survey on the species.

𝘎𝘶𝘢𝘪𝘢𝘨𝘰𝘳𝘨𝘪𝘢 喜歡吃什麼？What does 𝘎𝘶𝘢𝘪𝘢𝘨𝘰𝘳𝘨𝘪𝘢 like to eat？

𝘎𝘶𝘢𝘪𝘢𝘨𝘰𝘳𝘨𝘪𝘢係濾食者，唔似得石珊瑚，𝘎𝘶𝘢𝘪𝘢𝘨𝘰𝘳𝘨𝘪𝘢同大多數軟珊瑚一樣，佢哋冇共生嘅蟲黃藻去提供養份，會主要用觸手捉以海洋裏面嘅浮游生物同埋微生物為食。

𝘎𝘶𝘢𝘪𝘢𝘨𝘰𝘳𝘨𝘪𝘢 is a filter-feeder. Unlike hard corals, 𝘎𝘶𝘢𝘪𝘢𝘨𝘰𝘳𝘨𝘪𝘢 and many other octocorals do not obtain nutrients from photosynthetic symbionts. Instead, they mainly filter water and capture plankton and tiny particles as food with their tentacles.

𝘎𝘶𝘢𝘪𝘢𝘨𝘰𝘳𝘨𝘪𝘢 喜歡吃什麼？（續）What does 𝘎𝘶𝘢𝘪𝘢𝘨𝘰𝘳𝘨𝘪𝘢 like to eat？(Con't)

喺實驗室入邊，我哋會餵佢哋食啱啱孵化嘅豐年蝦BB同埋粉狀嘅珊瑚食物。按下連結，喺條片度睇吓佢哋點樣捉嘢食啦！

In the laboratory, they are fed with newly-hatched brine shrimp and powdered marine plankton. Click to see how they catch food with their tentacles!