Doughnuts, Oreo cookies: The colourful sea slugs of Singapore and those racing to record them

Published: Nov 02, 2026, 01:58 PM

Off the busy coast of Pulau Hantu, one of Singapore’s southern islands, exists a tiny marine slug that resembles a cluster of iced doughnuts.

The doughnut doto ( Doto greenamyeri ), as it is known, is one of more than 160 species of sea slugs that have been recorded in Singapore’s waters.

They can be found in a wide range of marine habitats around Singapore’s islands, from coral reefs in the waters south of the country to the mangroves in Kranji.

Not all of them have been formally inducted into Singapore’s halls of science and many are still considered undescribed species.

These sea slugs can be as small as a jelly bean , and the process of searching for and finding these gem-like creatures has fascinated marine enthusiasts.

Their vibrant colours and slow movements also make them a favourite for scuba divers looking for an easy subject to photograph.

The doughnut doto, for instance, is so alluring that divers have travelled the world for a chance to spot it.

The doughnut doto nudibranch (Doto greenamyeri) off Pulau Hantu. PHOTO: TOH CHAY HOON

The doughnut doto nudibranch (Doto greenamyeri) off Pulau Hantu.

PHOTO: TOH CHAY HOON

“Singapore is privileged to be one of the locations where people can see this,” said sea slug enthusiast Toh Chay Hoon. “Before it was found here in the 2010s, divers would fly to Bali just to shoot it.”

While scientists worldwide catalogue sea slugs and study their unique traits for biomedical research, formal studies on Singapore’s native species remain scarce.

But the records of a faithful team of hobbyists who patrol Singapore’s shores and subtidal waters have contributed to a growing body of knowledge about their diversity.

Among them is Toh, who has authored many records documenting their existence for Singapore’s Lee Kong Chian Natural History Museum.

The 49-year-old, who runs the @seaslugsofsg Instagram account, discovered the thrill of finding sea slugs when someone pointed out a dotted nudibranch ( Jorunna funebris ) to her in 2003 . She was then being trained as a guide at Pulau Ubin’s Chek Jawa.

In her pursuit of the slugs over the next decades, she learnt that the secret to spotting them is understanding their diet. “You can find them where their food is,” said Toh, who is a senior executive at the National University of Singapore (NUS).

For instance, the dotted nudibranch, which looks like an Oreo cookie, tends to be found chomping on a blue sponge.

Meanwhile, the sargassum sea slug ( Crosslandia sp. ) blends perfectly with the seaweed that gave it its common name.

A Hypselodoris infucata nudibranch at an intertidal area off Changi Beach. PHOTO: LIU JIANLIN

A Hypselodoris infucata nudibranch at an intertidal area off Changi Beach.

A passion for learning and the opportunity to contribute to marine science have driven fellow hobbyist Liu Jianlin to pen several records. He has purchased more than 10 books about sea slugs, with his costliest vintage purchase setting him back $200.

The 36-year-old researcher at the Institute of Mental Health has surveyed the shores since he was an undergraduate at NUS.

This passion has taken him to even Australia, where he wound up looking for sea slugs at 3am in winter.

In August, Singapore announced plans for a new industrial island, called the western island, which will involve the reclamation of several southern islands.

Toh estimated that Pulau Hantu, which is potentially part of that cluster of isles, has about 100 species of sea slugs. These amount to roughly 60% of sea slugs recorded in Singapore.

She explained that the high species diversity is partly due to the island’s popularity as a dive spot, which makes the slugs much easier to find.

On plans for the redevelopment of the area, Liu said: “Every time I go, I start to have a new sense of appreciation for it .”

Sea slugs v marine flatworms

These ornate creatures are frequently confused with each other. Beyond their flamboyant appearance, they differ in fundamental ways.

These are slimy, soft-bodied, spineless animals. Most lack shells, relying instead on chemical defences to survive. They tend to move slowly.

These are ribbon-like, spineless creatures that have no respiratory systems and body cavities. They tend to move faster than sea slugs.

Most have horn-like sensory organs on their heads called rhinophores, which help them smell and find food. Some use other structures to sense their surroundings.

They have pseudotentacles formed from folds on the fringes of their bodies, which they use to sense their surroundings.

They breathe through gills. Nudibranchs, a type of sea slugs, are distinguished by their exposed gills, among other features.

They lack gills. Instead, they absorb oxygen directly through their outer membranes.

Leaf sheep sea slug (”Shaun the Sheep”)

Blue dragon nudibranch

Doughnut doto nudibranch

Sargassum nudibranch

发布时间：2026年11月2日 下午1:58

在新加坡南部岛屿之一的普劳汉图繁忙的海岸附近，生活着一种体型很小的海洋蛞蝓，它看起来像一簇裹着糖霜的甜甜圈。

这种被称为甜甜圈海蛞蝓（Doto greenamyeri）的海蛞蝓，是新加坡水域中记录在案的 160 多种海蛞蝓之一。

从新加坡南部海域的珊瑚礁到克兰芝的红树林，在新加坡岛屿周围的各种海洋栖息地都能找到它们的身影。

并非所有物种都已正式列入新加坡科学名人堂，许多物种仍被认为是未描述的物种。

这些海蛞蝓的体型可以像一颗果冻豆那么小，寻找和发现这些宝石般生物的过程一直令海洋爱好者着迷。

它们鲜艳的色彩和缓慢的动作也使它们成为潜水员寻找易于拍摄对象时的首选。

例如，甜甜圈形状的海龟非常迷人，以至于潜水员们走遍世界各地，只为有机会一睹它的风采。

汉图岛附近的甜甜圈多托裸鳃类动物（Doto greenamyeri）。照片：杜才勋

汉图岛附近的甜甜圈多托裸鳃类动物（Doto greenamyeri）。

照片：杜彩勋

“新加坡很荣幸成为人们可以看到这种海蛞蝓的地方之一，”海蛞蝓爱好者杜才勋说道。“在2010年代新加坡发现这种海蛞蝓之前，潜水员们会飞往巴厘岛只为拍摄它们。”

尽管世界各地的科学家都在对海蛞蝓进行分类，并研究它们的独特特征以进行生物医学研究，但对新加坡本土物种的正式研究仍然很少。

但是，一支忠实的业余爱好者团队在新加坡海岸和潮下带水域巡逻的记录，为人们了解它们的多样性做出了贡献。

其中包括 Toh，他为新加坡李光前自然历史博物馆撰写了许多记录，记载了它们的存在。

这位 49 岁的女子运营着 Instagram 账号 @seaslugsofsg，她在 2003 年发现了寻找海蛞蝓的乐趣。当时有人向她指出了一种斑点裸鳃类动物（Jorunna funebris）。那时她正在乌敏岛的仄爪哇接受导游培训。

在接下来的几十年里，她一直致力于研究蛞蝓，并逐渐了解到发现它们的秘诀在于了解它们的饮食。“哪里有食物，哪里就有它们，”新加坡国立大学（NUS）高级主管杜女士说道。

例如，看起来像奥利奥饼干的斑点海蛞蝓，经常被发现正在啃食蓝色的海绵。

与此同时，马尾藻海蛞蝓（Crosslandia sp.）与赋予它俗名的海藻完美地融合在一起。

一只暗色海蛞蝓（Hypselodoris infucata）在樟宜海滩潮间带活动。摄影：刘建林

在樟宜海滩潮间带发现的一只暗色海蛞蝓（Hypselodoris infucata）。

对学习的热情以及为海洋科学做出贡献的机会，促使业余爱好者刘建林撰写了多项纪录。他购买了十多本关于海蛞蝓的书籍，其中最贵的一本老书花费了他200美元。

这位 36 岁的心理卫生研究所研究员从新加坡国立大学读本科时就开始勘测海岸线。

这种热情甚至让他远赴澳大利亚，在冬天的凌晨 3 点，他竟然在那里寻找海蛞蝓。

8 月，新加坡宣布了建设一座名为“西部岛屿”的新工业岛的计划，该计划将填海造陆，占用南部几个岛屿。

Toh估计，Pulau Hantu（可能是该群岛的一部分）大约有100种海蛞蝓。这约占新加坡记录在案的海蛞蝓总数的60%。

她解释说，物种多样性高的部分原因是该岛作为潜水胜地很受欢迎，这使得人们更容易找到蛞蝓。

谈到该地区的重建计划，刘先生说：“每次我去那里，都会对它产生新的欣赏之情。”

海蛞蝓 vs 海洋扁形虫

这些华丽的生物经常被混淆。除了它们艳丽的外表之外，它们在本质上也存在差异。

这些动物体表黏滑，身体柔软，没有脊椎。它们大多没有壳，而是依靠化学防御机制来生存。它们的行动通常很缓慢。

这些生物呈带状，没有脊椎，也没有呼吸系统和体腔。它们的移动速度通常比海蛞蝓快。

大多数动物头部都有角状的感觉器官，称为嗅角，帮助它们嗅闻和寻找食物。有些动物则利用其他结构来感知周围环境。

它们身体边缘的褶皱形成了假触手，用来感知周围环境。

它们用鳃呼吸。裸鳃类动物是一种海蛞蝓，其特征之一就是裸露的鳃。

它们没有鳃，而是直接通过外膜吸收氧气。

叶子绵羊海蛞蝓（“小羊肖恩”）

蓝龙裸鳃类动物

甜甜圈海蛞蝓

马尾藻裸鳃类动物