![IMG_0894 A red-fingered marsh crab with eyes on short stalks and orange-red front claws](/content/dam/doe/sws/schools/f/fieldofmar-e/images/IMG_0894.png.thumb.1280.1280.png)
![IMG_0896 An aerial view of a red-fingered marsh crab with 8 legs and 2 front claws](/content/dam/doe/sws/schools/f/fieldofmar-e/images/IMG_0896.png.thumb.1280.1280.png)
![IMG_0895 Front pincer-like claws of red-fingered marsh crab](/content/dam/doe/sws/schools/f/fieldofmar-e/images/IMG_0895.png.thumb.1280.1280.png)
![F45FE915-1C2A-41C5-B2FB-0E23FB4EC620 Short eye stalks widely spaced at each side of the head of a red-fingered marsh crab](/content/dam/doe/sws/schools/f/fieldofmar-e/image/F45FE915-1C2A-41C5-B2FB-0E23FB4EC620.png.thumb.1280.1280.png)
![IMG_0899 A red-fingered marsh crab on wet mud](/content/dam/doe/sws/schools/f/fieldofmar-e/images/IMG_0899.png.thumb.1280.1280.png)
![562576F5-C9A5-4835-AA01-CB59DD5A5877 Mangrove forest with muddy ground, protruding pencil roots, small seedlings and twisted trees](/content/dam/doe/sws/schools/f/fieldofmar-e/image/562576F5-C9A5-4835-AA01-CB59DD5A5877.jpeg.thumb.1280.1280.jpg)
![IMG_0898 Red-fingered marsh crab close to a fallen mangrove seed](/content/dam/doe/sws/schools/f/fieldofmar-e/images/IMG_0898.jpeg.thumb.1280.1280.jpg)
![9034CD01-2B0B-4ECB-B898-5838CDE9ED3E Pincer-like claws and hard shell of a red-fingered marsh crab](/content/dam/doe/sws/schools/f/fieldofmar-e/image/9034CD01-2B0B-4ECB-B898-5838CDE9ED3E.jpeg.thumb.1280.1280.jpg)
![IMG_0897 Red-fingered marsh crab on the edge in round burrow in the mud](/content/dam/doe/sws/schools/f/fieldofmar-e/images/IMG_0897.png.thumb.1280.1280.png)
![IMG_0900 Red-fingered marsh crab in narrow horizontal crevice](/content/dam/doe/sws/schools/f/fieldofmar-e/images/IMG_0900.png.thumb.1280.1280.png)
The red-fingered marsh crab is an invertebrate that lives in the intertidal zone of the mangrove forest, often in great numbers. The intertidal zone is the area between high and low tides.
Red-fingered marsh crabs get their name from the bright red-orange tips on the claws of the adult crabs. They are from the order Decapoda which means they have 10 legs. The two legs at the front of the crab have been modified into the claws that display the red tips.
Their scientific name is Parasesarma erthrodactyla.
The body of a red-fingered marsh crabs is around three centimetres wide when fully grown. The males have bright green shells and their characteristic red tipped pincer-like claws. The red-fingered marsh crab has short eye stalks meaning that the eyes sit just above the shell. Length of eye stalks helps scientists to distinguish the red-fingered marsh crab from another common species found in the mangroves, the semaphore crab.
Red-fingered marsh crabs live on the mangrove forest floor. They construct burrows in the muddy intertidal zone. The burrows provide safety from predators during low tide. Crabs will often be seen scurrying sideways into the nearest burrow when threatened.
Red-fingered marsh crabs play a vital role in the recycling of nutrients in the mangrove ecosystem, much in the same way as worms do in terrestrial – land – environments.
They are omnivorous meaning they eat both plant and animal material such as mangrove leaves, insects, small fish and other crabs. They use their big claws to help break down the food prior to eating.
Red-fingered marsh crabs are an important part of the food web in the mangrove ecosystem. Common predators include fish during high tide and shore birds during low tide.
Red-fingered marsh crabs use their large claws for feeding and defence.
Red-fingered marsh crabs are well adapted to living on land during low tide. Their hard exoskeleton helps store water which is flushed over their gills allowing them to breathe when they are out of the water. The exoskeleton also prevents the crabs from drying out and provides protection from any predators.
The bright green colour of the exoskeleton may be a camouflage as it resembles the seeds from nearby mangroves.
Their ability to move quickly sideways and retreat down a burrow is an effective behaviour for escaping predators. Their flat bodies allow them to hide in small crevices.
Museums Victoria. n.d. Parasesarama erythodactyla (Hess, 1865). [online] Available at: <https://collections.museumsvictoria.com.au/species/8673>
The Maroochy Wetlands Sanctuary. n.d. Crabs of Maroochy Wetlands. [online] Available at: <https://www.maroochywetlandssupport.org.au/wp-content/uploads/2013/04/Crabs-of-Maroochy-Wetlands.pdf>
A red-fingered marsh crab - “Photo 155768647” by tmyknckr. CC BY-NC 4.0 DEED (cropped)
Count the number of legs on the crab. Don't forget to include their front claws! - “Photo 155768655” by tommyknocker. CC BY-NC 4.0 DEED (cropped)
Red-fingered marsh crabs live in the mud of mangrove forests. - “Photo 108265304” by cgraf. CC BY-NC 4.0 DEED (cropped)
The claws of red-fingered marsh crabs have bright red tips. - “Photo 107487735” by craiginnature. CC BY-NC 4.0 DEED (cropped)
Red-fingered marsh crabs have short eye stalks. - “Photo 155765830” by tmyknckr. CC BY-NC 4.0 DEED (cropped)
They eat mangrove leaves and insects. - “Red-fingered Marsh Crab” by Gary Williams. CC BY-NC 4.0 DEED (edited)
Red-fingered marsh crabs have numerous adaptations that allow them to survive out of water. - “Photo 281200773” - by John Eichler. CC BY-NC 4.0 DEED
Claws and an exoskeleton provide protection for red-fingered marsh crabs. - “Photo 267539730” by arachon. CC BY-NC 4.0 DEED
Red-fingered marsh crabs retreat to burrows when threatened. - “Photo 62504441” by pratyeka. CC BY-NC 4.0 DEED (cropped)
Flat bodies allow red-fingered marsh crabs to hide in crevices. - “Photo 255375191” by ravencon. CC BY-NC 4.0 DEED (cropped)
address
Field of Mars Reserve
Pittwater Road
East Ryde NSW 2112
telephone 02 9816 1298
We’d like to acknowledge the Wallumedegal Peoples of the Darug Nation, the Traditional Custodians of the land on which we stand and pay our respects to Elders past and present.
Copyright for this website is owned by the State of New South Wales through the Department of Education. For more information go to http://www.dec.nsw.gov.au/footer/copyright.