Johora+singaporensis


 *  Singapore freshwater crab ** **//Johora singaporensis// Ng, 1986 **



=Introduction= toc The crabs of the genus //Johora// can be found in areas of higher elevation (more than 100 m above sea level) of Peninsular Malaysia and its surrounding islands (1). They are usually found under rocks or in leaf litter around clean and clear waters of higher velocity (2).

//Johora singaporensis// is endemic to Singapore (i.e. can only be found in Singapore) and its distribution on the island is highly restricted (refer to **Distribution**). In fact, it was regarded as critically endangered by the International Union for the Conservation of Nature (IUCN) (3). During the IUCN’s world Conservation Congress, it was included in the list of the top 100 most threatened species in the world (4). Like other freshwater decapods, they are scavengers and detritivores which play an important role in the recycling of nutrients in the freshwater ecosystem (5).

=Name = **Etymology** (how it got its name): The species is named after its locality, Singapore, where it is endemic to.

**Binomial name** (scientific name): //Johora singaporensis// Ng, 1986

**Vernacular name** (common name): Singapore freshwater crab or Singapore stream crab

**Synonyms** (scientific names that were previously used): //Potamon (Potamon) johorense// Roux 1936 //Potamon johorense// Ong 1965 //Potamiscus (Johora) johorensis johorensis// Bott 1966 //Stoliczia (Johora) johorensis johorensis// Bott 1970

=Distribution= //Johora singaporensis// can only be found in Singapore. It only inhabits certain streams near Bukit Timah, Bukit Batok and Bukit Gombak (Figure 1)





=Biology =

Diet
<span style="font-family: Arial,Helvetica,sans-serif;">In general, freshwater decapods are nocturnal and regarded as scavengers and omnivores (6, 7, 8). As efficient shredders of leaf litter, freshwater crabs are mainly detritivores (7). Due to the bank vegetation of their natural habitat, plant material can be readily found and hence make up a large part of their diet (1,6).

<span style="font-family: Arial,Helvetica,sans-serif;">//Johora singaporensis// has been recorded to predate on oligochaetes found in soft mud to supplement its diet of mainly detritus (9, 10). Recently, //J. singaporensis// was observed to scavenge on a dead mole cricket out of water (Figure 2). This behaviour was reported to be unusual as the behaviour of feeding on terrestrial insects out of water have never been recorded (11). As compared to sympatric species like //Irmengardia johnsoni// and //Parathelphusa maculata//, //J. singaporensis// is observed to prefer animal matter (12).

The video below shows close up of how a freshwater crab eats. The crab featured is //Geosesarma peraccae,// a freshwater crab that can be found in Singapore too. Unlike //J. singaporensis//, it is not endemic to Singapore and is semi-terrestrial. media type="custom" key="24369628" align="center"

<span style="font-family: Arial,Helvetica,sans-serif;">Lifecycle
<span style="font-family: Arial,Helvetica,sans-serif;">As a primary freshwater crab, //Johora singaporensis// spend their entire life in freshwater. Their mating behaviour is not very well studied (13). Mating occurs during the moist and humid wet season (October – December) as most gravid females are found then, occurring mostly on stream banks under rocks (9,12,13)

<span style="font-family: Arial,Helvetica,sans-serif;">The eggs of //J. singaporensis//, like all primary freshwater crabs, are large and yolky. Female crabs carry and brood the eggs in her abdomen where will hatch into tiny fully-formed crabs (Figure 3). The direct development of eggs is an important adaptation to life in freshwater streams. This avoids the free swimming larvae stage that is usually present for marine crabs.Free swimming larvae would most likely be washed downstream to the sea where they will most likely not survive. For the first couple of weeks, the mother will carry the newly hatched young in her abdomen until they are able to lead independent lives (12).

<span style="font-family: Arial,Helvetica,sans-serif;">Osmoregulation and respiration
<span style="font-family: Arial,Helvetica,sans-serif;">Living in freshwater conditions will result in the loss of body salts. Hence, //Johora singaporensis// is capable of reabsorbing salt from their urine for osmoregulation (5).

<span style="font-family: Arial,Helvetica,sans-serif;">Similar to all freshwater crabs, //J. singaporensis// spends quite some time in the terrestrial environment too (Figure 4). Hence, they possess “pseudo-lungs” in their gill chambers to allow them to breathe in atmospheric oxygen (5).

<span style="font-family: Arial,Helvetica,sans-serif;">These adaptations allow //J. singaporensis// to survive in the short term without water. However, water is still essential for their survival due to the need to excrete ammonia (5).

<span style="font-family: Arial,Helvetica,sans-serif;">Moulting
<span style="font-family: Arial,Helvetica,sans-serif;"> <span style="font-family: Arial,Helvetica,sans-serif;">Crabs need to moult in order to grow. The crab will pump in water to swell its body resulting in the old exoskeleton to split at specific lines. During moulting, the crab is most vulnerable as any stress or disturbance may result in its death. The moulted crab is very soft and the hardening of the new exoskeleton via the incorporation of calcium salts from its reserves or the water will take a few days.

<span style="font-family: Arial,Helvetica,sans-serif;">After the moult, the crab will eat more to grow into its larger exoskeleton (14). As forested freshwater streams has very little calcium salts, the old shell can be eaten by the crab after its mouthparts harden to conserve valuable calcium salts (Ng, 1988, 1990) (Figure 5).

=**Ecology**=

<span style="font-family: Arial,Helvetica,sans-serif;">Habitat
<span style="font-family: Arial,Helvetica,sans-serif;">//Johora singaporensis// is mainly an aquatic crab, but it can also survive out of water if the surroundings are humid and cool (13). They prefer streams in hilly areas, where waters in the main stream are clean, fast flowing and of pH 7 (14) (Figure 6). They can be found hiding under leaf litter or under rocks, where they make simple chambers to reside in (13, 14). Hence, the pristine conditions needed by //J. singaporensis// to thrive severely restricts its habitat range resulting in conservation issues (see **Conservation** below).

<span style="font-family: Arial,Helvetica,sans-serif;">Ecological services
<span style="font-family: Arial,Helvetica,sans-serif;">Freshwater decapods play an important role in the nutrient cycling of the freshwater stream ecosystem (10, 15). Being equipped with pincer-like appendages for efficient shredding, //Johora singaporensis// and other freshwater decapods speeds up the decomposition process by tearing plant matter and rotting animal carcasses into smaller pieces.

=Conservation=

<span style="font-family: Arial,Helvetica,sans-serif;">//Johora singaporensis// is “uniquely Singaporean” as crab expert Professor Peter Ng mentioned in an article in The Straits Times (12 June 2013). 99% of the crabs in Singapore can be found in other parts of the world. //Johora singaporensis// evolved on the island in isolation and can only be found here.
 * <span style="font-family: Arial,Helvetica,sans-serif;">Why conserve? **

<span style="font-family: Arial,Helvetica,sans-serif;">Singapore, being a small island, severely lacks areas with hilly streams. The distribution of //Johora singaporensis// is has been restricted to a few forest streams in Bukit Batok, Bukit Gombak and Bukit Timah. Only Bukit Timah has a designated protected reserve. In the past, the small 39 ha primary forest area was able to sustain a thriving population despite the deterioration of the rest of Bukit Timah Nature Reserve into a secondary forest and an abandoned farmland. Recently, it was found that the population in Bukit Timah has been drastically reduced and close to local extinction (2, 17It was postulated to be caused by the acidification of stream waters due to acid rain (2). Urban pollution resulting in the silting of waters may also degrade the pristine waters that //J. singaporensis// inhabits (16). Now, the crabs inhabit a 10 ha area that that is subjected to development (17). Populations that are remaining lie within unprotected areas, and hence may face habitat degradation.

<span style="font-family: Arial,Helvetica,sans-serif;">In the book “Priceless or Worthless”, where the top 100 most threatened species of the world was nominated by members of the IUCN Species Survival Commission Specialist Groups and Red List Authorities, //Johora singaporensis// was unfortunately one of the candidates (4).
 * <span style="font-family: Arial,Helvetica,sans-serif;">No laughing matter **

<span style="font-family: Arial,Helvetica,sans-serif;">In Singapore, newspaper articles on the plight of //Johora singaporensis// have been published to create public awareness. <span style="font-family: Arial,Helvetica,sans-serif;"> <span style="font-family: Arial,Helvetica,sans-serif;">More research can be done to understand more about Johora singaporensis – its breeding habits and the level of tolerance of its habitat parameters. A two-year project by Raffles Museum of Biodiversity Research (RMBR) and National Parks Board (NParks) was initiated to study the status of //Johora singaporensis//, in attempt to strike its name off the 100 most threatened species list of the IUCN.
 * <span style="font-family: Arial,Helvetica,sans-serif;">Is it possible to prevent the extinction of our unique crab? **

<span style="font-family: Arial,Helvetica,sans-serif;">Preservation of its natural habitats is also crucial. Conservation of large patches of forest is needed to maintain the pristine water quality to allow //J. singaporensis// to thrive (17). When exploring nature reserves and other natural areas, we can also do our part by not littering or damaging vegetation. Take nothing but photographs and leave nothing but footprints behind.

=Morphology=

General body parts of a freshwater crab
Only the body parts used in the description will be labelled for reference.


 * 1. Dorsal View (Figure 7)**

**2. Frontal view (Figure 8)**

**3. Third maxiliped (Figure 9)** Crabs have a pair of third maxilipeds that cover their mouth.
 * <span style="font-family: Arial,Helvetica,sans-serif;">4. Ventral View (Figure 10) **

**5. Gonopod 1 (G1) (Figure 11)** A pair of gonopods is found in the abdominal cavity (under the abdominal flap) of male crabs. They serve a copulatory function. Being tubular, they assist the transfer of spermatophores to the females. In freshwater crab taxonomy, these structures are extremely important as they are usually used for species identification.

Description of //Johora singaporensis//
<span style="font-family: Arial,Helvetica,sans-serif;">Do note that colour is generally not used for species identification in freshwater crabs. Firstly, colour is perceived differently for different people. Secondly, in preserved specimens, the colours are usually faded.

<span style="font-family: Arial,Helvetica,sans-serif;">However, in the field, preliminary species identification can be done using colour before more detailed studies. Hence, colour is included in the description below (9,14,18).
 * **View** ||= **Part** || **Characteristic** ||  ||
 * ~  ||= Carapace || * Shape: Squarish
 * H-groove: Prominent
 * Cristae: P ost-orbital cristae distinct but low, anterior to epigastric cristae, and separated by narrow furrow
 * Frontal margin: Sinuous
 * Epibranchial tooth: One low and indistinct tooth
 * Anterolateral margin: C <span style="color: #000000; font-family: Arial,Helvetica,sans-serif; vertical-align: baseline;">onvex, slightly serrated and crested, adjacent areas with many small tubercles
 * Posterolateral margin: Almost straight, converging
 * Colouration: Dirty brown in larger specimens, mottled brown and orange in smaller specimens || [[image:_A140056.jpg width="248" height="202" caption="Carapace (Photo: Kenny Chua)"]] ||
 * ~ Dorsal ||= Cheliped || * Size: Asymmetrical
 * Proportion: Fingers (responsible for pinching) longer than palm
 * Margins:
 * Dorsal proximal margins of both dactyli with two rows of forward pointing granules
 * Inner angle of carpus with one sharp spine
 * Colouration:
 * B<span style="font-family: Arial,Helvetica,sans-serif;">rown with lower oblique two-thirds of palm and pollex orange
 * <span style="font-family: Arial,Helvetica,sans-serif;">Tips of fingers all orange
 * <span style="font-family: Arial,Helvetica,sans-serif;">Inner surface of merus purplish-red (pale or absent in smaller specimens) || [[image:Cheliped(Description).png width="230" height="93" align="center" caption="Right chela (Photo: Kenny Chua)"]] ||
 * ~  ||= Ambulatory Legs || * Margins:
 * Smooth, unarmed (no spine on merus)
 * Distal part of dorsal margin of meri of second and third leg serrated
 * Colouration<span style="font-family: Arial,Helvetica,sans-serif;">:
 * <span style="font-family: Arial,Helvetica,sans-serif;">Brown with narrow proximal lateral light orange strip
 * <span style="font-family: Arial,Helvetica,sans-serif;">Dactyli more orange || [[image:Ambulatry legs.png width="141" height="183" align="center" caption="Left ambulatory legs (Photo: Kenny Chua)"]] ||
 * ~ Frontal ||= Third Maxiliped || * Texture: <span style="font-family: Arial,Helvetica,sans-serif;">Outer surface hirsutous, with small granules
 * <span style="font-family: Arial,Helvetica,sans-serif;">Merus: Centrally depressed
 * <span style="font-family: Arial,Helvetica,sans-serif;">Ischium: Deep median sulcus
 * <span style="font-family: Arial,Helvetica,sans-serif;">Exopod: Long flagellum, length more than half of merus width
 * <span style="font-family: Arial,Helvetica,sans-serif;">Mandibular palp: Simple terminal segment
 * <span style="font-family: Arial,Helvetica,sans-serif;">Epistome: Anterior margin smooth
 * <span style="font-family: Arial,Helvetica,sans-serif;">Colouration:
 * <span style="font-family: Arial,Helvetica,sans-serif;">Ischium purplish-red
 * M<span style="font-family: Arial,Helvetica,sans-serif;">erus brownish
 * <span style="font-family: Arial,Helvetica,sans-serif;">Central parts pale orange
 * <span style="font-family: Arial,Helvetica,sans-serif;"> In smaller specimens, purple patches pale or absent || [[image:3rd maxiliped.png width="230" height="189" align="center" caption="Third maxilipeds (Photo: Kenny Chua)"]] ||
 * ~ Ventral ||= Abdomen || * Shape: Triangular
 * Abdominal segments:
 * Seven segments
 * Telson longer than segment 6, tip rounded, margins straight
 * Colouration: Pale orange (white in smaller specimens) || [[image:Abdomen.png width="217" height="202" align="center" caption="Abdomen (Photo: Daniel Ng)"]] ||
 * ~ Internal ||= G1 || * Terminal segment: Long, rod-like
 * Subterminal segment: distal portion slender, neck-like || [[image:Johora G1.jpg width="200" height="188" align="center" caption="Ventral and dorsal view of left G1 (re illustrated from Ng,1988)"]] ||

=Diagnosis= <span style="font-family: Arial,Helvetica,sans-serif;">In Singapore, there are two other species of freshwater crabs that are mainly aquatic, //Parathelphusa maculata// and //Irmengardia johnsoni.//

<span style="font-family: Arial,Helvetica,sans-serif;">//Parathelphusa maculata// also known as the lowland freshwater crab, is one of the most common crabs not only in Singapore, but also Malaysia (13). As it can be seen from their vernacular name, they prefer lowland streams. These hardy crabs have a high tolerance for low oxygen conditions and can be found in muddy waters and stagnant pools. <span style="font-family: Arial,Helvetica,sans-serif;">//Irmengardia johnsoni// or Johnson’s freshwater crab like //Johora singaporensis//, is endemic to Singapore. Although it is recorded to have a less restricted distribution than //J. singaporensis//, it is still considered vunerable by the IUCN. Unlike //J. singaporensis// which are found in highland streams, //I. johnsoni// can be found in secondary lowland streams too, where they inhabit leaf litter of muddy areas (14).


 * <span style="font-family: Arial,Helvetica,sans-serif;">How can //Johora singaporensis// be differentiated from other mainly aquatic freshwater crabs of Singapore? **

__<span style="font-family: Arial,Helvetica,sans-serif;">In the field: __
<span style="font-family: Arial,Helvetica,sans-serif;">In the field, it is often not possible to differentiate the crabs based on internal structures. Hence, the table below shows other characters that can help the identification of //Johora singaporensis.//

<span style="font-family: Arial,Helvetica,sans-serif;">•Squarish in shape <span style="font-family: Arial,Helvetica,sans-serif;">•Covered with short stiff hairs <span style="font-family: Arial,Helvetica,sans-serif;">•Low and indistinct epibranchial tooth on anterolateral margin <span style="font-family: Arial,Helvetica,sans-serif;">•Colouration: Dirty brown with purplish tinge || •Quadrilateral in shape <span style="font-family: Arial,Helvetica,sans-serif;">•No hairs <span style="font-family: Arial,Helvetica,sans-serif;">•Two epibranchial teeth on anterolateral margin <span style="font-family: Arial,Helvetica,sans-serif;">•Colouration: Olive to dark brown, younger specimens have a light olive brown carapace with spots which gradually fade off as they grow || <span style="font-family: Arial,Helvetica,sans-serif;">•Squarish in shape <span style="font-family: Arial,Helvetica,sans-serif;">•No hairs <span style="font-family: Arial,Helvetica,sans-serif;">•Low and indistinct epibranchial tooth on anterolateral margin <span style="font-family: Arial,Helvetica,sans-serif;">•Colouration: Dirty dark grey or brown || <span style="font-family: Arial,Helvetica,sans-serif;">•Palms not inflated in larger males <span style="font-family: Arial,Helvetica,sans-serif;">•Colouration: Brown, with lower parts orange <span style="font-family: Arial,Helvetica,sans-serif;"> and inner surface of the chelipedmerus purplish red || •Palms not inflated in larger males <span style="font-family: Arial,Helvetica,sans-serif;">•Colouration: Brown, covered with darker brown spots || <span style="font-family: Arial,Helvetica,sans-serif;">•In large males, cheliped palms inflated and blade-like <span style="font-family: Arial,Helvetica,sans-serif;">•Colouration: Bright orange in larger specimens, brown in smaller specimens || <span style="font-family: Arial,Helvetica,sans-serif;">•Subterminal spine on ambulatory legs absent <span style="font-family: Arial,Helvetica,sans-serif;">•Colouration: Brown with narrow proximal <span style="font-family: Arial,Helvetica,sans-serif;"> lateral light orange strip giving it a banded appearance,dactyli more orange || •Subterminal spine on ambulatory legs distinct <span style="font-family: Arial,Helvetica,sans-serif;">•Colouration: Brown || •Subterminal spine on ambulatory legs short and blunt <span style="font-family: Arial,Helvetica,sans-serif;">•Colouration: Dirty dark grey or brown || •In rocky areas which trap plant detritus near the stream || • Under the leaf litter near their burrows in the mud || •Under leaf litter beds and detritus near the stream ||
 * =  ||= //**Johora singaporensis**// ||= **//Parathelphusa maculata//** ||= **//Irmengardia johnsoni//** ||
 * = <span style="font-family: Arial,Helvetica,sans-serif;">Carapace || [[image:taxo4254/_A140056.jpg width="272" height="219" align="center" caption="(Photo: Kenny Chua)"]]
 * <span style="font-family: Arial,Helvetica,sans-serif;">Chelipeds || [[image:johora cheliped.png width="277" height="187" align="center" caption="(Photo: Kenny Chua)"]]
 * <span style="font-family: Arial,Helvetica,sans-serif;">Ambulatory legs || [[image:Ambulatry legs.png width="187" height="225" align="center" caption="(Photo: Kenny Chua)"]]
 * <span style="font-family: Arial,Helvetica,sans-serif;">Habitat preference || [[image:DSC_0759.jpg width="294" height="201" align="center" caption="(Photo: Daniel Ng)"]]

__<span style="font-family: Arial,Helvetica,sans-serif;">In the laboratory: __
<span style="font-family: Arial,Helvetica,sans-serif;">In laboratory conditions, it is easy to distinguish //Johora singaporensis// from //Irmengardia johnsoni// and //Parathelphusa maculata//. //J. singaporensis// belongs belongs to the family Potamidae while //I. johnsoni// and //P. maculata// belongs to Gecarcinucidae. Using a higher magnification, we can use these two features below to accurately identify //J. singaporensis.//


 * 1) <span style="font-family: Arial,Helvetica,sans-serif;"> Potamids (where //J.singaporensis// belongs) have a 3-segmented mandibular palp with a simple terminal segment whereas gecarcinucids (//I. johnsoni// and //P. maculata//) have a 2-segmented bilobed mandibular palp (19) (Figure 12).

<span style="font-family: Arial,Helvetica,sans-serif;"> 2. The G1s of the three species are very different (Figure 13).



=<span style="font-family: Arial,Helvetica,sans-serif;">Type information =

<span style="font-family: Arial,Helvetica,sans-serif;">The original description by Ng (1986) was based on the holotype.

<span style="font-family: Arial,Helvetica,sans-serif;">**Holotype:** Male (17.3 by 14.0 mm) collected from Bukit Timah by P. K. L. Ng in 1984 (18). Currently stored in the Zoological Reference Collection (ZRC) of the Raffles Museum of Biodiversity Research, National University of Singapore.


 * <span style="font-family: Arial,Helvetica,sans-serif;">Paratypes: **
 * **Year** || **Number/ Sex** || **Deposited in** || **Collector** || **Location** ||
 * 1984 || * 2 females
 * 1 female || * ZRC || * P. K. L. Ng || * Same as holotype ||
 * 1984 || * 1 male
 * 2 males || * RCCU 1 || * P. K. L. Ng || * Same as holotype ||
 * 1984 || * 5 males, 4 females || * RMNH<span style="font-family: Arial,Helvetica,sans-serif; vertical-align: super;">2 || * H.P.Ng
 * P. K. L. Ng
 * L. B. Holthuis || * Same as holotype ||
 * 1985 || * 9 males, 8 females || * ZRC || * H. P. Ng
 * P. K. L. Ng || * Stream in Bukit Batok Hill ||
 * 1985 || * 2 males || * MZB 3 || * H. P. Ng
 * P. K. L. Ng || * Stream in Bukit Batok Hill ||
 * 1) <span style="font-family: Arial,Helvetica,sans-serif;">Reference Collection of the Chulalongkorn University
 * 2) <span style="font-family: Arial,Helvetica,sans-serif;">Rijksmuseum van Natuurlijke Historie, Leiden, Netherlands
 * 3) <span style="font-family: Arial,Helvetica,sans-serif;">Museum Zoologicum Bogoriense, Bogor, Indonesia

=<span style="font-family: Arial,Helvetica,sans-serif;">Phylogeny =

<span style="font-family: Arial,Helvetica,sans-serif;">A minimum evolution tree based on the combined 16S rRNA, COI and H3 genes for the genus //Johora// was constructed by Yeo et al. (2007) (Figure 14). Results show that //Johora// is a monophyletic clade, with three well developed clades within it. //Johora// used to be a subgenus of //Stoliczia//, however, in 1987, Ng elevated the group to a full genus and this is supported by the phylogenetic study.

<span style="font-family: Arial,Helvetica,sans-serif;">Crabs of the genus //Johora// share a long flagellum on the exopod of the third maxilliped (i.e. main synapomorphy of //Johora//). //Johora singaporensis// belongs to the //johorensis// clade. Crabs of this clade are generally small- to medium-sized species, possess low epigastric and postorbital carapace cristae with a tapered and curved or hooked G1 terminal segment (20). //Johora singaporensis// forms a monophyletic group that is sister taxa to the rest of the //johorensis// clade. The main apomorphic character of //J. singaporensis// is the long, rod-like terminal segment and very slender subterminal segment (9,14,18).



=More information on freshwater crabs=

A short introduction on Singapore's freshwater crabs Singapore's freshwater crabs and shrimps Freshwater crabs at risk of extinction

= = =Literature cited=

<span style="font-family: "Arial","sans-serif"; font-size: 13.33px;">1) Ng, P. K. L., 1988. //<span style="font-family: "Arial","sans-serif";">The Freshwater Crabs of Peninsular Malaysia and Singapore //. Department of Zoology, University of Singapore, Shinglee Press, Singapore. 156 pp.

<span style="font-family: "Arial","sans-serif"; font-size: 13.33px;">2) Tan, H. T. W., L. M. Chou, D. C. J. Yeo & P. K. L. Ng, 2010. //<span style="font-family: "Arial","sans-serif";">The Natural Heritage of Singapore. 3rd Edition. // Pearson Prentice Hall, Singapore. 323 pp.

<span style="font-family: "Arial","sans-serif"; font-size: 13.33px;">3) <span style="color: #000000; font-family: "Arial","sans-serif"; font-size: 13.33px;">Esser, L., N. Cumberlidge & D. C. J. Yeo, 2008. //<span style="font-family: "Arial","sans-serif";">Johora singaporensis //. In: IUCN 2012. IUCN Red List of Threatened Species. Version 2013.1.<span style="font-family: "Arial","sans-serif"; font-size: 13.33px;">[] <span style="color: #000000; font-family: "Arial","sans-serif"; font-size: 13.33px;">. (Accessed 10 Nov.2013).

<span style="font-family: "Arial","sans-serif"; font-size: 13.33px;">4) <span style="color: #000000; font-family: "Arial","sans-serif"; font-size: 13.33px;">Baillie, J. E. M. & E. R. Butcher, 2012. Priceless or worthless? The world’s most threatened species. //<span style="font-family: "Arial","sans-serif";">Zoological Society of London //, UK. 63 pp.

<span style="font-family: "Arial","sans-serif"; font-size: 13.33px;">5) <span style="color: #000000; font-family: "Arial","sans-serif"; font-size: 13.33px;">Dobson, M., 2004. Freshwater crabs in Africa. //<span style="font-family: "Arial","sans-serif";">Freshwater Forum //, **<span style="font-family: "Arial","sans-serif";">21 **: 3–26.

<span style="font-family: "Arial","sans-serif"; font-size: 13.33px;">6) <span style="color: #000000; font-family: "Arial","sans-serif"; font-size: 13.33px;">Dominey, W. J. & A. M. Snyder, 1988. Kleptoparasitism of freshwater crabs by cichlid fishes endemic to Lake Barombi Mbo, Cameroon, West Africa. //<span style="font-family: "Arial","sans-serif";">Environmental Biology of Fishes //, **<span style="font-family: "Arial","sans-serif";">22 **: 155–160.

<span style="font-family: "Arial","sans-serif"; font-size: 13.33px;">7) <span style="color: #000000; font-family: "Arial","sans-serif"; font-size: 13.33px;">Hill, M. P. & J. H. O’Keeffe, 1992. Some aspects of the ecology of the freshwater crab ( //<span style="font-family: "Arial","sans-serif";">Potamonautes perlatus // Milne Edwards) in the upper reaches of the Buffalo River, Eastern Cape Province, South Africa. //<span style="font-family: "Arial","sans-serif";">South African Journal of Aquatic Sciences //, **<span style="font-family: "Arial","sans-serif";">18 **: 42–50.

<span style="font-family: "Arial","sans-serif"; font-size: 13.33px;">8) <span style="color: #000000; font-family: "Arial","sans-serif"; font-size: 13.33px;">Harrison, E. M., 1995. The zonation of freshwater crabs with altitude in a mountain stream in the East Usambara Mountains, Tanzania. //<span style="font-family: "Arial","sans-serif";">Frontier Tanzania Expedition Report TZ943 //. Pp. 1–56.

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<span style="font-family: "Arial","sans-serif"; font-size: 13.33px;">15) <span style="color: #000000; font-family: "Arial","sans-serif"; font-size: 13.33px;">Crowl, T. A., W. H., McDowell, A. P. Covich & S. L. Johnson, 2001. Freshwater shrimp effects on detrital processing and nutrients in a tropical headwater stream. //<span style="font-family: "Arial","sans-serif";">Ecology //,**<span style="font-family: "Arial","sans-serif";">82 **:775–783.

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 * Acknowledgements**

I would like to thank:

Dr Darren Yeo and Daniel Ng for providing some papers for reference.

Kenny Chua and Lam Kar Mun for the photographs.

Lim Zi Min for cartoon inspirations.

Lam Kar Mun for her kind feedback.

Eunice Soh and Ong Xin Rui for website formatting help.