Nav: Home

HKU marine ecologists discover and name the first endemic tree-climbing crab

April 10, 2017

The Mangrove Ecology and Evolution Lab, led by Dr Stefano Cannicci at the Swire Institute of Marine Sciences (SWIMS) and School of Biological Sciences, the University of Hong Kong (HKU), has recently discovered, described and named a new species of mangrove-climbing micro-crab from Hong Kong, Haberma tingkok, and published the description in ZooKeys, a peer-reviewed and open access international journal dedicated to animal taxonomy.

The new species has been given the scientific name of Haberma tingkok, since all the specimens found at present were spotted at a height of approximately 1.5 to 1.8 metres above chart datum, walking along the branches of the mangroves of the Ting Kok area. The crabs are small, less than a centimetre long, predominantly dark brown, with a squarish carapace, very long legs and orange claws. It represents the second endemic mangrove crab species described in Hong Kong. The previous one, Pseudosesarma patshuni, was described in 1975.

Discovery of a new endemic mangrove crab in over 40 years

This endemic tree-crab was previously unknown to science and it is only known, at present, to have come from Tolo Harbour, Hong Kong. It is Hong Kong's first truly arboreal crab, i.e. living on the branches and canopies of mangroves and breathing air. Its closest relatives, i.e. crabs of the same genus, are only known to be found in the mangroves of Singapore and Indonesian New Guinea, but they are all normal crabs that live in the mud - they do not climb trees.

The first known individual of Haberma tingkok was found in the mangroves of Ting Kok at the end of last summer, during one of the routine biodiversity samplings carried out by a group of HKU undergraduate students majoring in Ecology & Biodiversity and research assistants. At the time, they were conducting a multi-institutional project funded by the Hong Kong Environment and Conservation Fund (ECF) "Assessing the Marine Biodiversity and Ecology of Tolo Harbour and Channel, with particular Reference to Coastal Marine Environments of Ting Kok and Shuen Wan Hoi - Phase I." The Project is coordinated by the Director of SWIMS, Professor Gray A Williams, and managed by Dr Kevin Ho King-yan.

During the sampling, Mr Steven Wong Ho-tin, a year four undergraduate student majoring in Ecology and Biodiversity at HKU, found a mature, female crab of unusually small dimensions on the mangrove branches and showed it to Dr Cannicci, Associate Professor at HKU School of Biological Sciences, who immediately realised that the crab was not a common one in Hong Kong as it had some much-specialised features. Although the vast majority of crabs are marine and freshwater species, there are some groups that, along their evolutionary history, developed the uncommon ability to climb trees, especially in a mangrove habitat. This crab had the characteristics of a tree climber, extremely elongated legs, with respect to the body, which is very flattened, and she was carrying eggs, a clear indication that it had extreme confidence in living up in the branches of tress.

Since the identification of this group of crabs, i.e. the common mangrove crabs known as the Sesarmidae, can only be finalised by studying males, a large scale crab-hunt started, involving the whole group of students and researchers from HKU. It was Miss Cherry Cheung Cheuk-yiu, a research assistant at HKU, who finally spotted the first known male of this species. Under the microscope, in Dr Cannicci's laboratory, it was clear that the crab was the first record of the crab genus Haberma in Hong Kong, since in this group the males have a peculiar locking-system on the second and third walking, probably for grasping females while mating. This new identification was confirmed by Dr Cannicci during a visit to the Lee Kong Chian Natural History Museum of the National University of Singapore and published by Dr Cannicci and Professor Peter Ng Kee-lin, Director of the Museum.

The discovery of this new crab species shows how little is known about the diversity of crabs in Hong Kong. On the basis of the number of known species from Japan and Taiwan, marine biologists from all over the world estimate that we only know up to 50-60% of the real diversity of coastal and littoral crabs in Hong Kong, which is far less than the ratio known for many other marine species. That is why the above-mentioned project on marine biodiversity in the Tolo Harbour area led by HKU and involving five other universities in Hong Kong is of paramount importance, and echoed the development of the Biodiversity Strategy Action Plan (BSAP) initiated by the Government of the Hong Kong Special Adminsitrative Region under the United Nations' Convention of Biological Diversity.
The journal article on Haberma tingkok is available at

Information on the project 'Assessing the Marine Biodiversity and Ecology of Tolo Harbour and Channel, with particular Reference to Coastal Marine Environments of Ting Kok and Shuen Wan Hoi - Phase I' is available at

About the HKU Mangrove Ecology and Evolution Laboratory

The recently established Mangrove Ecology and Evolution Laboratory (the Laboratory), based at SWIMS, HKU, is interested in various aspects of mangrove ecology and crab biology. The group aims to study the patterns of diversity of crabs and molluscs in Hong Kong, East African and South East Asian mangroves and their role in ecosystem functioning. There is a steady and alarming trend in decrease of mangrove forests all over the world and the SWIMS Mangrove Lab is deeply involved in their conservation, as members of the International Union for Conservation of Nature Mangrove Specialist Group. In particular, the group is involved in studying the impact of pollution and land reclamation on Hong Kong mangroves, and it will lead the two-year project "Hong Kong mangroves: where are they now?", funded by the Hong Kong Environment and Conservation Fund and aiming at assessing the biodiversity and health of mangrove forests, for conservation and management purposes.

For more information and activities about the Laboratory, please visit

The University of Hong Kong

Related Biodiversity Articles:

About the distribution of biodiversity on our planet
Large open-water fish predators such as tunas or sharks hunt for prey more intensively in the temperate zone than near the equator.
Bargain-hunting for biodiversity
The best bargains for conserving some of the world's most vulnerable salamanders and other vertebrate species can be found in Central Texas and the Appalachians, according to new conservation tools developed at the National Institute for Mathematical and Biological Synthesis (NIMBioS) at the University of Tennessee, Knoxville.
Researchers solve old biodiversity mystery
The underlying cause for why some regions are home to an extremely large number of animal species may be found in the evolutionary adaptations of species, and how they limit their dispersion to specific natural habitats.
Biodiversity offsetting is contentious -- here's an alternative
A new approach to compensate for the impact of development may be an effective alternative to biodiversity offsetting -- and help nations achieve international biodiversity targets.
Biodiversity yields financial returns
Farmers could increase their revenues by increasing biodiversity on their land.
Biodiversity and wind energy
The location and operation of wind energy plants are often in direct conflict with the legal protection of endangered species.
Mapping global biodiversity change
A new study, published in Science, which focuses on mapping biodiversity change in marine and land ecosystems shows that loss of biodiversity is most prevalent in the tropic, with changes in marine ecosystems outpacing those on land.
What if we paid countries to protect biodiversity?
Researchers from Sweden, Germany, Brazil and the USA have developed a financial mechanism to support the protection of the world's natural heritage.
Grassland biodiversity is blowing in the wind
Temperate grasslands are the most endangered but least protected ecosystems on Earth.
The loss of biodiversity comes at a price
A University of Cordoba research team ran the numbers on the impact of forest fires on emblematic species using the fires in Spain's Doñana National Park and Segura mountains in 2017 as examples
More Biodiversity News and Biodiversity Current Events

Trending Science News

Current Coronavirus (COVID-19) News

Top Science Podcasts

We have hand picked the top science podcasts of 2020.
Now Playing: TED Radio Hour

Listen Again: Meditations on Loneliness
Original broadcast date: April 24, 2020. We're a social species now living in isolation. But loneliness was a problem well before this era of social distancing. This hour, TED speakers explore how we can live and make peace with loneliness. Guests on the show include author and illustrator Jonny Sun, psychologist Susan Pinker, architect Grace Kim, and writer Suleika Jaouad.
Now Playing: Science for the People

#565 The Great Wide Indoors
We're all spending a bit more time indoors this summer than we probably figured. But did you ever stop to think about why the places we live and work as designed the way they are? And how they could be designed better? We're talking with Emily Anthes about her new book "The Great Indoors: The Surprising Science of how Buildings Shape our Behavior, Health and Happiness".
Now Playing: Radiolab

The Third. A TED Talk.
Jad gives a TED talk about his life as a journalist and how Radiolab has evolved over the years. Here's how TED described it:How do you end a story? Host of Radiolab Jad Abumrad tells how his search for an answer led him home to the mountains of Tennessee, where he met an unexpected teacher: Dolly Parton.Jad Nicholas Abumrad is a Lebanese-American radio host, composer and producer. He is the founder of the syndicated public radio program Radiolab, which is broadcast on over 600 radio stations nationwide and is downloaded more than 120 million times a year as a podcast. He also created More Perfect, a podcast that tells the stories behind the Supreme Court's most famous decisions. And most recently, Dolly Parton's America, a nine-episode podcast exploring the life and times of the iconic country music star. Abumrad has received three Peabody Awards and was named a MacArthur Fellow in 2011.