第 1129 號，共 1 402 號

Christmas tree hydroid

Pennaria disticha

只是會痛會痛，但不會對你造成嚴重傷害。

螫吃：肉

The Christmas tree hydroid is a small, branching sea creature that grows in colonies on rocks and hard surfaces in shallow water. It is found in warm seas around the world, and it is common in the Mediterranean Sea. Scientists have used it to study how animals catch their prey.1

分布在

Warm waters worldwide; probably began in the western Atlantic Ocean, and is common in the Mediterranean Sea1

大西洋, 太平洋, 印度洋, 加勒比海, 地中海, 墨西哥灣, 帝汶海與阿拉弗拉海, 孟加拉灣, 加利福尼亞灣

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It grows in shallow water, attached to hard surfaces such as rocks and man-made structures, in places with some water movement. On reefs it is usually found in less-exposed spots and in crevices. It has also spread on ropes and other structures placed in the sea.1

長度

30 cm (1 ft)1

最高速度

大約 0,01 km/h（0,01 mph）

游泳, 粗略估計

牠吃什麼？

The polyps spread their tentacles to catch small zooplankton that drift past. Stinging cells on the tentacles immobilise the prey, then the crown bends over and the prey is killed and pushed into the mouth.1

Christmas tree hydroid 的照片 — Christmas tree hydroid。照片：Stephen Thorpe。 CC BY 4.0, iNaturalist.

怎麼認出牠

Colonies have many branching stems, up to 30 cm high, arranged in a tree-like shape1
The stalks are dark brown or blackish, but are often coated with algae and diatoms, giving them a muddy look1
The tiny whitish polyps are tinged with red1
Each polyp has many slender tentacles at its base and up to twelve tentacles with knobbed tips around its mouth1

毒液力量

螫

毒液從螫針出來。

牠的毒液有什麼作用？

Contact with a rope on which this hydroid was growing caused an acute, painful skin inflammation (dermatitis) in several people. Contact with the stinging cells on its tentacles is the cause.1

牠對人有多危險？

對人的危險: 疼痛可能會非常痛，但幾乎從來不會很嚴重。

Several people who touched a rope covered in this hydroid got an acute, painful dermatitis. No deaths are known.1

如果牠螫人

離開水裡，把觸手拿掉（戴手套或用布）。
熱帶箱形水母：在螫傷處倒醋至少 30 秒，求救，並準備好做心肺復甦術（CPR）。藍瓶水母和大多數其他水母：用海水沖洗，再用熱水止痛。

一定要先打緊急電話（112、000、911）。這是一般急救指引，不是醫療建議。急救基本知識

注意安全

絕對不要碰、抓或捉弄野生動物，就算是很小的動物，就算牠看起來在睡覺或已經死了也一樣。
給牠空間。如果遇到了，保持冷靜，慢慢往後退，讓牠自己離開。
如果被牠螫了：保持冷靜，保持不動，打緊急電話（112、000、911）或趕快去醫院。記住牠的樣子，有照片會很有幫助。

牠不是想來抓你。牠用毒液來捕捉食物或保護自己，而且牠更想躲起來。更多安全知識

在世界上的哪裡？

非洲亞洲歐洲北美洲南美洲澳洲與大洋洲太平洋大西洋印度洋地中海加勒比海墨西哥灣帝汶海與阿拉弗拉海孟加拉灣加利福尼亞灣

牠有多大？

牠有多長？

跟 9 塊玩具積木排成一排一樣長比花園蝸牛還慢

Christmas tree hydroid 跟「你」比起來有多大？

只是在你的瀏覽器裡做算術。什麼都不會儲存，也不會傳送到任何地方。

牠有多快？

一隻海馬 大約 0,0015 km/h (0 mph)

Christmas tree hydroid 大約 0,01 km/h (0,01 mph)

一隻花園蝸牛 大約 0,05 km/h (0,03 mph)

值得知道

小知識

It has spread around the world largely through people's maritime activities, by attaching to ships and structures.1

It has been used in research into how animals capture their prey.1

Colonies grow by budding, which forms new feeding polyps.1

Its free-swimming larvae drift with the plankton before settling on a hard surface.1

給毒液專家

學名: Pennaria disticha
類群: 水母和會螫人的海洋生物
家人: Pennariidae2
排序: Anthoathecata
各大洲: 大西洋, 太平洋, 印度洋, 加勒比海, 地中海, 墨西哥灣, 帝汶海與阿拉弗拉海, 孟加拉灣, 加利福尼亞灣, 海洋
寶寶: Females release up to six eggs. Each embryo develops within a day or so into a free-swimming larva called a planula, which later settles on a hard surface to start a new colony.1
對人的危險: 2 / 5: 疼痛3