Perisesarma+eumolpe

__Face-banded Sesarmine Crab__ // Perisesarma eumolpe // Last updated by Wong Jinfa on 25 November 2012. toc == Fig. 1. Front view of //Perisesarma eumolpe.// (Photo: Jinfa & Christopher©) >>> =media type="custom" key="21391154"= Vid. 01. Photograph slideshow of //P. eumolpe.// (Photos: Jinfa, Maosheng & Christopher©)

= Name = > > Synonoms: //Sesarma (Chiromantes) eumolpe// De Man, 1895 3] > > [This is a general name used to refer to all //Perisesarma// sp.] ||  || Fig. 2. Dorsal view of //P. eumolpe.// (Photo: Jinfa©) ||
 * * Binomial: //Perisesarma eumolpe// (De Man, 1895) 1]
 * Synonoms: //Sesarma (Perisesarma) eumolpe// De Man, 1895 2]
 * Vernacular: Face-banded Seasarmine Crab

= Introduction =

//Perisesarma eumolpe// is a common crab that is found in the mangroves of the Indo-pacific region. 4] It has colourful facial bands that are usually iridescent blue, yellow , green or turquoise. 5] Unlike most other animals that can only see in black and white, these crabs can see in colour ! 6] This allows them to recognize and communicate to one another with their facial bands. For example, bigger crabs often have blue bands which indicate that they are mature and "fitter", so weaker individuals would know not to mess with that individual. 7]

Colour is also good indication of fitness as the crabs have to obtain enough carotenoids in their diet to produce it. 8] This comes from eating leaves. 9] While foraging, crabs also disturb the muddy substrate and help aerate the anaerobic soil of the mangrove, such that mangrove plants can grow better. 10] Thus, the crabs are very important in the mangroves and can be easily spotted at Sungei Buloh Nature Reserve (Singapore) at low tide. Can you spot the crab in Fig. 3? Click on it after you find it.

media type="file" key="Perisesarma eumolpe flash v4.swf" width="704" height="536" Fig. 3. //P. eumople// in Mandai mangroves. (Animation: Jinfa©)

Did you notice the water on the face of the crab in Fig. 3? The crabs are able to stay out of water for long periods because of the net-like hairs on their face that trap water. Deoxygenated water that has passed through the gills can be directed to these hairs where they are aerated with oxygen before it is moved back. 11]

The crabs also communicate to one another by rubbing the bumps on their claws together to produce sound and listen to one another with their legs ! 12]

When a male crab finds a potential mate, it often has to guard the female from other males before copulation. After successfully mating, the male would leave the female to take care of the fertilised eggs that are held in her abdomen until a full or new moon. During the high tide of such a night, the female will spawn the eggs that will hatch into planktonic larvae. 13]

For more detailed explanation on these interesting facts, refer to the Biology section,

= Distribution =

//P. eumolpe// is found in the Indo-pacific region 4] . Fig. 5 has the locations of where crabs were found or collected in some publications, in addition to locations indicated on Flickr. I have also included the locations and photographs of some crabs that I have found personally. The locations demarcated with an asterisk are from very old records, that might have changed such that they are no longer habitats for //P. eumolpe//. Fig. 4. //P. eumolpe// hiding under roots (Photo: Jinfa©) || media type="custom" key="21354638" Fig. 5. Distribution of //P. eumolpe//
 * **Indo-Pacific** 4] :
 * Indonesia
 * Batavia, Semmelink colony (Jarkata) in 1882* 3]
 * North coast of Java, Buitendijk colony in 1905* 3]
 * North-west coast of Java, Buitendijk colony in 1906* 3]
 * Malaysia
 * Penang in 1895* 2]
 * Merbok estuary 9]
 * Port Swettenham, Selangor in 1934* 14]
 * Singapore
 * Kranji mangroves [[|Flickr® link]] [[|WildSingapore link]]
 * Mandai Besar mangroves 15]
 * Mandai Kechil mangroves 5]6]7]8]12]15]16]17]18]
 * Pasir Ris Park mangroves [[|Flickr® link]] [[|WildSingapore link]]
 * Pulau Semakau mangroves [[|Flickr® link]] [[|WildSingapore link]]
 * Sungei Buloh mangroves [[|WildSingapore link]]
 * River Jurong in 1934 * 14]
 * Pulau Senang in 1934* 14]
 * Pulau Bukon in 1934* 14]
 * Johore Strait 14]
 * Vietnam
 * Can Gio Biosphere Reserve, Ba Ria-Vung Tau 19][[|Flickr® link]] || [[image:Perisesarma eumolpe habitat.png width="538" height="383"]]

= Diagnosis =

There are 23 species of face-banded crabs (//Perisesarma// sp.) found in the world and six that are recorded in Singapore. 20]21] Two common, similar looking f ace-banded crabs that can be found living side by side are //Perisesarma eumolpe// and //Perisesarma indiarum// (Fig. 6) 5]. media type="file" key="p. eumolpe differences.swf" width="836" height="642" Fig. 6. Photographs of //P. eumolpe// (left) and //P. indiarium// (right) (Animation: Jinfa© with photographs by Dr. Naruse, Jinfa and Christopher©)

It is often difficult to tell them apart in the wild. This is because when they are covered in mud, one can only see their red chelae (pincers) and iridescent blue, yellow or green facial bands (personal observation). There are ways though to tell the two crabs apart: . Fig. 7. Tubercles on the dactyl of //P. eumolpe// (left) and //P. indiarum// (right). (Photo: Jinfa & Dr. Naruse© ) > .  Fig. 8. Tubercle illustrations on the dactyl (Illustration reproduced with permission from Boon //et al//, 2009)
 * === Tubercles ===
 * Tubercles are small rounded projections found on the upper surface of the dactyl (terminal segment of the pincer) (Fig. 7).
 * // P. eumolpe // has tubercles which are smaller and more numerous compared to //P. indiarum// (Fig. 7 & 8)//.// 12]
 * This method requires the use of close inspection of the chelae and thus can be difficult to use on a living crab!

To learn more on how //P. eumolpe// produces sound with its chelae, refer to the Biology (Stridulation) section. || . Fig. 9. Comparison of the 3rd maxilliped of //P. eumolpe// (left) and //P. indiarium// (right) (Photo: Peiya©)
 * === Third Maxillipeds ===
 * The third maxillipeds make up the upside down V on the crab's face
 * The third maxillipeds for // P. eumolpe // is black in colour compared to the blue, yellow or green coloured maxilliped for //P. indiarum// (Fig. 9). 18]
 * However, this might not an accurate tool for identification as colouration is affected by diet. Thus, If a crab does not obtain enough food (carotenoids), the colours might not be reflected. 7]
 * However, this might not an accurate tool for identification as colouration is affected by diet. Thus, If a crab does not obtain enough food (carotenoids), the colours might not be reflected. 7]

To learn more on how to identify //P. eumolpe//, refer to the Anatomy and Description section. ||

= Anatomy = Fig. 10. Dorsal (top) view of //P. eumolpe// with annotations. (Photo: Jinfa©) || Fig. 11. Front view of //P. eumolpe// with annotations. (Photo: Jinfa©) || Females have a circular abdomen (Fig. 12) while males have a triangular abdomen (Fig. 13). > >>  Fig. 12. Ventral (bottom) view of a //P. eumolpe// female (Photo: Jinfa & Christopher©) >>>> Fig. 13. Ventral (bottom) view of a //P. eumolpe// male (Photo: Jinfa & Christopher©) || Upon fertilization, the <span style="color: #008080; font-family: Arial,Helvetica,sans-serif; font-size: 90%;">eggs are held by the female in her abdominal cavity <span style="font-family: Arial,Helvetica,sans-serif; font-size: 90%;">before she spawns (Fig. 15). <span style="color: #ffffff; font-family: Arial,Helvetica,sans-serif; font-size: 50%;">> Fig. 14. Location of vulva in a female (Photo: Jinfa & Maosheng©) >>>> Fig. 15. Eggs held in the abdominal segments of a female //P. eumolpe// (Photo: Jinfa & Maosheng©) || <span style="color: #ffffff; font-family: Arial,Helvetica,sans-serif; font-size: 50%;">> Fig. 16. Male //P. eumolpe// have a pair of gonopods (Photo: Jinfa©) || For more information on how the crabs reproduce, refer to the Biology (Reproduction) section
 * The annotations (Fig. 10 & 11) were made with reference to Ng, 1988 22] and help of [|Dr. Ng Ngan Kee.] ||
 * [[image:Perisesarma eumolpe anatomy 1b.png width="800" height="466"]]
 * [[image:taxo4254/Perisesarma eumolpe anatomy 2.png width="800" height="528"]]
 * [[image:taxo4254/Perisesarma eumolpe anatomy 2.png width="800" height="528"]]
 * <span style="font-family: Arial,Helvetica,sans-serif; font-size: 90%;">Male and female crabs can be identified by the <span style="color: #008080; font-family: Arial,Helvetica,sans-serif; font-size: 90%;">differences in the shape of the abdomen <span style="font-family: Arial,Helvetica,sans-serif; font-size: 90%;"> on the ventral side (underside) of the crab.
 * <span style="font-family: Arial,Helvetica,sans-serif; font-size: 90%;">Male and female crabs can be identified by the <span style="color: #008080; font-family: Arial,Helvetica,sans-serif; font-size: 90%;">differences in the shape of the abdomen <span style="font-family: Arial,Helvetica,sans-serif; font-size: 90%;"> on the ventral side (underside) of the crab.
 * <span style="font-family: Arial,Helvetica,sans-serif; font-size: 90%;">The female's opening where sperm is injected into is called the <span style="color: #008080; font-family: Arial,Helvetica,sans-serif; font-size: 90%;">vulva <span style="font-family: Arial,Helvetica,sans-serif; font-size: 90%;">(Fig 14). Females have two vulvae.
 * <span style="font-family: Arial,Helvetica,sans-serif; font-size: 90%;">The female's opening where sperm is injected into is called the <span style="color: #008080; font-family: Arial,Helvetica,sans-serif; font-size: 90%;">vulva <span style="font-family: Arial,Helvetica,sans-serif; font-size: 90%;">(Fig 14). Females have two vulvae.
 * <span style="font-family: Arial,Helvetica,sans-serif; font-size: 90%;">The male's reproductive organs used to insert into the female's two vulvae are called <span style="color: #008080; font-family: Arial,Helvetica,sans-serif; font-size: 90%;">gonopods <span style="font-family: Arial,Helvetica,sans-serif; font-size: 90%;">(Fig. 16)
 * <span style="font-family: Arial,Helvetica,sans-serif; font-size: 90%;">The male's reproductive organs used to insert into the female's two vulvae are called <span style="color: #008080; font-family: Arial,Helvetica,sans-serif; font-size: 90%;">gonopods <span style="font-family: Arial,Helvetica,sans-serif; font-size: 90%;">(Fig. 16)

= Description =

The crab was named and first described by <span class="wiki_link_ext">De Man (Fig. 17). 2] For more information on its taxonomy, please refer to the Taxonomy section. Fig. 17. Screenshot of De Man's description (Image: BioStor) ||  || Readers, please be advised that colour is not a good technique to identify a species as:
 * [[image:taxo4254/p eumolpe Description.jpg width="325" height="427"]]
 * It can be subjective (different people can view the same colour differently) 23]
 * It is usually lost with time in preserved specimens (as seen in Fig. 17). 24]

However, colour has been included in the subsequent descriptions as they are more practical to be applied in the field before more robust checks can be applied. If you come across any unfamiliar terms, please refer to the Anatomy section for reference. ​ Fig. 18. Front view of preserved //P. eumolpe.// (Photo: Jinfa©) || > (Anterolateral and posterolateral margins of carapace not clearly demarcated) > (Presence of anterolateral tooth is a > distinguishing feature of //Perisesarma// > according to De Man 2] . However, more recent > studies have shown that this characteristic is not > very consistent or well defined for some //Perisesarma// sp. 25]26]27] ) Fig. 19a. Carapace location on //P. eumolpe// (Illustration: Jinfa©) ||  || Fig. 19b. Squarish carapace of //P. eumolpe.// (Photo: Jinfa©) || > endostome and subobital region > iridescent blue, yellow, green or turquoise. 5] Fig. 20a. Facial band location on //P. eumolpe// (Illustration: Jinfa©) ||  || Fig. 20b. //P. eumolpe// with different coloured facial bands.(Photos: Jinfa & Maosheng©) || > maxillipeds with <span style="color: #008080; font-family: Arial,Helvetica,sans-serif; font-size: 90%;">mandibles <span style="font-family: Arial,Helvetica,sans-serif; font-size: 90%;">exposed > (Distinguishing feature of Sesarmidae & Grapsidae) <span style="font-family: Arial,Helvetica,sans-serif; font-size: 70%; vertical-align: super;">22] Fig. 21a. Third maxilliped locations on //P. eumolpe// (Illustration: Jinfa©) ||  || media type="file" key="p. eumolpe moving maxilliped.swf" width="281" height="204" media type="file" key="p. eumolpe moving maxilliped 2.swf" width="280" height="205" Fig. 21b. Third maxillipeds of //P.// //eumolpe// tucked in (top left), stretched out (top right) & moving (bottom). (Photos & Animation: Jinfa©) || > (net-like) pattern at the pterygostomial region. > (Distinguishing feature of Sesarmidae) 22] Fig. 22a. Pterygostomial region on //P. eumolpe// (Illustration: Jinfa) ||  || Fig. 22b. Pterygostomial region of //P. eumolpe// has retiuclated setae//.// (Photos: Jinfa©) || > on the upper surface of the dactyl 12] > sometimes unequal in size 3] Fig. 23a. Cheliped locations of //P. eumolpe// (Illustration: Jinfa©) ||  || Fig. 23b. Red chelipeds of //P. eumolpe.// (Photo: Jinfa & Christopher©) || Fig. 24a. Walking leg locations of //P. eumolpe// (Illustration: Jinfa©) ||  || Fig. 24b. Dactylus of //P. eumolpe.// (Photo: Jinfa©) || > To find out how to tell the difference between //P. eumolpe// & another similar looking crab, //P. indiarum//, refer to the Diagnosis section
 * === Carapace ===
 * Squarish shape 22]
 * Squarish shape 22]
 * Black colour with small yellow patches
 * Two anterolateral tooth on the carapace
 * === Facial Bands ===
 * Found at the frontal region, epistome ,
 * Found at the frontal region, epistome ,
 * The colours of the facial bands are usually
 * === Third Maxillipeds ===
 * <span style="font-family: Arial,Helvetica,sans-serif; font-size: 90%;">Is <span style="color: #008080; font-family: Arial,Helvetica,sans-serif; font-size: 90%;">black <span style="font-family: Arial,Helvetica,sans-serif; font-size: 90%;">in colour <span style="font-family: Arial,Helvetica,sans-serif; font-size: 70%; vertical-align: super;">5]
 * <span style="color: #008080; font-family: Arial,Helvetica,sans-serif; font-size: 90%;">Rhomboidal gap <span style="font-family: Arial,Helvetica,sans-serif; font-size: 90%;">present between third
 * <span style="color: #008080; font-family: Arial,Helvetica,sans-serif; font-size: 90%;">Rhomboidal gap <span style="font-family: Arial,Helvetica,sans-serif; font-size: 90%;">present between third
 * <span style="font-family: Arial,Helvetica,sans-serif; font-size: 90%;">Merus and ischium of third maxillipeds with <span style="color: #008080; font-family: Arial,Helvetica,sans-serif; font-size: 90%;">ridge <span style="font-family: Arial,Helvetica,sans-serif; font-size: 90%;"> (Distinguishing feature of Sesarmidae) <span style="font-family: Arial,Helvetica,sans-serif; font-size: 70%; vertical-align: super;">22]
 * === Pterygostomial Region ===
 * Short and stiff setae (hairs) form reticulated
 * Short and stiff setae (hairs) form reticulated
 * === Chelipeds (Pincers) ===
 * Red chelae
 * //P. eumolpe// has many small tubercles (bumps)
 * //P. eumolpe// has many small tubercles (bumps)
 * The left and right pincers can be
 * === Walking legs ===
 * Dactylus of legs with distinct spines 22]
 * Dactylus of legs with distinct spines 22]

= Biology =


 * === Facial Bands ===

The facial bands of //Perisesarma eumolpe// are used to communicate their gender, maturity level, nutritional status and other qualities with one another.

Firstly, the facial bands could be used by the crabs to recognize each other as conspecifics (members of the same species). When the facial bands of some of the crabs were blackened out in a study, other crabs seemed to ignore them. This could be because they were unable to recognize each other. 6]8] But, can these crabs really see colour? This was tested by Huang with heat associated learning. Crabs were observed to go in the direction of a Y-junction that had a different colour from the starting chamber that was heated up which suggested that they are able to see colour. 6]

Majority of male crabs also have a blue band while majority of the females have green bands. This are used by crabs to discriminate gender. 5]6]7] Females were also found to have a positive correlation between the intensity of blue and their size, functioning as indicators of their maturity level. 5]6] The contrasting blue bands could also function in conspecific signalling during contestation for territory and matings rights. 5]6] Males were observed to display mate-guarding behaviours, choosing to move towards the male in a Y-chamber displaying male and female andromorphs. 7] This indicates that males gain more by fighting off other male competitors than by trying to attract females. Furthermore, when the facial bands of a male crab was blackened out, another male displayed less aggressiveness to it. These suggest the facial bands were important for male-male assessment. 5]6] Females similarly approached the female andromorph in the Y-chamber. This might be because they stand to gain more by keeping other females away from their territory compared to finding a mate, especially if it is resource-rich and are home to males. 7] In addition, both sexes choose to approach more brightly coloured conspecifics. 16] These evidence suggest that facial bands are honest signals and are used for assessing an individual's resource holding potential. 7]8]16] Resource holding potential is the capability of an animal to win if it engages in a fight. If a crab is not fit, it would not be able to expend resources to produce costly colours. Thus, dull coloured crabs can mean the crab is less fit and so do not pose a threat. This would help the crabs to avoid unnecessary fighting and injuries and thus save their energy for other activities such as foraging or burrowing. 28]

>>>>>>>  Fig. 25. //P. eumople// with green facial band. (Photo: Jinfa©) >>>>>>>>>>>>>>>>> Fig. 26. //P. eumople// with blue facial band. (Photo: Jinfa©) ||
 * === Facial Bands & Carotenoids ===
 * === Facial Bands & Carotenoids ===

The colours in the facial bands are most likely a result of their carotenoid-based diets. Differing from other mangrove sesarmids that rely heavily on mangrove sediments for assimilating carbon, Perisesarma crabs also feed on mangrove leaves, which contain carotenoids. 7]9]17] Wang tested if diet would affect facial colours by starving and then re-feeding some crabs. The results were a reduction in facial band brightness and colour saturation during starvation which increased again upon re-feeding. 7]8] This suggest that the colours could be cartenoid-based as carotenoids cannot be synthesised de novo and have to be obtained from their diet. 7]8] Further support was found from high performance liquid chromatography analysis of extracted facial band tissues that confirmed the presence of carotenoids. 7]17]

media type="file" key="p. eumolpe fading band.swf" width="412" height="304" Vid. 02. Facial band of //P. eumolpe// fading over time. (Animation: Jinfa©)

For making this species page, I have also caught some crabs which I kept for about a month. In my glass tank, i had mangrove mud and leaves to ensure the crabs had enough food. However, I did observe that the one or two of the crabs with the yellow and green bands lost their colour completely within 2 weeks while crabs with the blue bands only became duller (personal observation). Fig. 28a. //P. eumolpe// with healthy facial bands. (Photo: Jinfa©) >>>>>>>>>>>>>>>>>>>>>>>>>> Fig. 28b. P. eumolpe with faded facial bands. (Photo: Jinfa©) ||
 * === Feeding Ecology ===
 * === Feeding Ecology ===

<span style="font-family: Arial,Helvetica,sans-serif; font-size: 90%;">//Perisesarma// comprises one of the highest biomass of crabs in the mangrove, performing many ecological roles in the mangrove. 29] As <span style="font-family: Arial,Helvetica,sans-serif; font-size: 90%;">//Perisesarma// feed on mangrove leaves, some of the <span style="color: #008080; font-family: Arial,Helvetica,sans-serif; font-size: 90%;">energy stored in the leaves stay in the mangrove system <span style="font-family: Arial,Helvetica,sans-serif; font-size: 90%;">, before they are lost when the tides wash them away. <span style="font-family: Arial,Helvetica,sans-serif; font-size: 70%; vertical-align: super;">10] <span style="font-family: Arial,Helvetica,sans-serif; font-size: 90%;"> Leaves that are broken into tiny pieces that not eaten and their faeces also enters the coprophagous food chain, providing food for other tiny organisms. 29] <span style="font-family: Arial,Helvetica,sans-serif; font-size: 90%;">During foraging and burrowing, the crabs also perform <span style="color: #008080; font-family: Arial,Helvetica,sans-serif; font-size: 90%;">bioturbation (stirring and mixing of the sediments), <span style="font-family: Arial,Helvetica,sans-serif; font-size: 90%;">which can affect the growth of and reproduction of mangrove plants. <span style="font-family: Arial,Helvetica,sans-serif; font-size: 70%; vertical-align: super;">10]19] <span style="font-family: Arial,Helvetica,sans-serif; font-size: 90%;"> //P. eumolpe// are primarily <span style="color: #008080; font-family: Arial,Helvetica,sans-serif; font-size: 90%;">sediment feeders <span style="font-family: Arial,Helvetica,sans-serif; font-size: 90%;">that also feed on <span style="color: #008080; font-family: Arial,Helvetica,sans-serif; font-size: 90%;">mangrove roots <span style="font-family: Arial,Helvetica,sans-serif; font-size: 90%;">and <span style="color: #008080; font-family: Arial,Helvetica,sans-serif; font-size: 90%;">leaves <span style="font-family: Arial,Helvetica,sans-serif; font-size: 90%;">. <span style="font-family: Arial,Helvetica,sans-serif; font-size: 70%; vertical-align: super;">18] <span style="font-family: Arial,Helvetica,sans-serif; font-size: 90%;"> In additional, they are highly opportunistic and were noticed to feed on animal remains as well. <span style="font-family: Arial,Helvetica,sans-serif; font-size: 70%; vertical-align: super;">18]19] <span style="font-family: Arial,Helvetica,sans-serif; font-size: 90%;"> They were also found to prefer <span style="color: #008080; font-family: Arial,Helvetica,sans-serif; font-size: 90%;">//Avicennia alba// <span style="font-family: Arial,Helvetica,sans-serif; font-size: 90%;">leaves to other Singapore mangrove plant species and had no preference for fresh or old leaves. <span style="font-family: Arial,Helvetica,sans-serif; font-size: 70%; vertical-align: super;">18]

media type="youtube" key="sA3gkVO4Fp8" height="290" width="420"media type="youtube" key="Oo4TouR2jds" height="290" width="420" Vid. 03. //P. eumolpe// feeding. (Video: Jinfa©) >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Vid. 04. //P. eumolpe// coming out of a mud pool and grooming itself before feeding. (Video: Jinfa©) ||
 * === Stridulation ===
 * === Stridulation ===

<span style="font-family: Arial,Helvetica,sans-serif; font-size: 90%;">Other than visual methods, //P. eumolp//e is also known to communicate with sound by <span style="color: #008080; font-family: Arial,Helvetica,sans-serif; font-size: 90%;">stridulation, especially during the night when their facial bands are not visible. <span style="color: #008080; font-family: Arial,Helvetica,sans-serif; font-size: 90%;">Sound is produced by rubbing the tubercles <span style="font-family: Arial,Helvetica,sans-serif; font-size: 90%;"> (Fig. 4 & 5 ) <span style="font-family: Arial,Helvetica,sans-serif; font-size: 90%;">on the dorsal side of their chelae together (Fig. 29). <span style="font-family: Arial,Helvetica,sans-serif; font-size: 70%; vertical-align: super;">12] <span style="font-family: Arial,Helvetica,sans-serif; font-size: 90%;">Boon //et al//. grouped the sound made by the crabs into <span style="color: #008080; font-family: Arial,Helvetica,sans-serif; font-size: 90%;">rasp train <span style="font-family: Arial,Helvetica,sans-serif; font-size: 90%;">and <span style="color: #008080; font-family: Arial,Helvetica,sans-serif; font-size: 90%;">rasp series <span style="font-family: Arial,Helvetica,sans-serif; font-size: 90%;">. <span style="font-family: Arial,Helvetica,sans-serif; font-size: 70%; vertical-align: super;">12] <span style="font-family: Arial,Helvetica,sans-serif; font-size: 90%;"> A rasp train is produced when one claw (rasping claw) is moved up and down repeatedly against the other stationary claw, between positions A1 and A2 (Fig. 27). <span style="font-family: Arial,Helvetica,sans-serif; font-size: 70%; vertical-align: super;">12] <span style="font-family: Arial,Helvetica,sans-serif; font-size: 90%;"> The rasp series is made up of a pure stridulation followed by the integral tap element. <span style="font-family: Arial,Helvetica,sans-serif; font-size: 70%; vertical-align: super;">12] <span style="font-family: Arial,Helvetica,sans-serif; font-size: 90%;"> Pure stridulation is a result of the crab moving its rasping claw upwards to reach position C from B, while the integral tap element is produced by striking the tip of the rasping claw on the propodus of the stationary contralateral claw (Fig. 27). <span style="font-family: Arial,Helvetica,sans-serif; font-size: 70%; vertical-align: super;">12]

Fig. 29. Movement of chelae to produce sound (Illustration reproduced with permission from Boon //et al//, 2009)

Sound is detected by the Barth's organ. This is found at the walking legs, on the underside of the meral-ischial joint, where the centre is bulging outwards from the surrounding depressed region (Fig. 30). 12]

Fig. 30. Barth's organ on the meral-ischial joint (Photo & Illustration: Jinfa©)

<span style="font-family: Arial,Helvetica,sans-serif; font-size: 90%;">Unlike other animals where displays are usually performed before contact (to minimize wastage of energy), //P. eumolpe// was observed to <span style="color: #008080; font-family: Arial,Helvetica,sans-serif; font-size: 90%;">display this stridulatory behaviour after contact, <span style="font-family: Arial,Helvetica,sans-serif; font-size: 90%;">especially after intense fights. This is very unusual as displays are usually done beforehand. Chen (2014) also found that stridulations were displayed by the winners after the fights. Thus, this behaviour is most likely a <span style="color: #008080; font-family: Arial,Helvetica,sans-serif; font-size: 90%;">victory display <span style="font-family: Arial,Helvetica,sans-serif; font-size: 90%;">, exclusively used for asserting victory. 40] ||
 * === Branchial Water Movement & Reticulated Setae ===
 * === Branchial Water Movement & Reticulated Setae ===

How do the crabs breathe when they are out of water? Water enters the branchial chamber by capillary action of the numnerous setae on the coxal joints of the walking legs. It then flows to the gills where gaseous exchange occurs before being pumped out. Most of the water that flows out would move across the pterygostomial region, which is covered with reticulated setae that traps it. 30] When on land, deoxygnated water that has passed through the gills can also be transported to the reticulated setae where it is aerated with oxygen before it is moved back to the branchial chamber. This gives the crab the ability to stay out of water for long periods. 11]

media type="youtube" key="FPsm1irrma4" height="286" width="498" Fig. 31. Water movement of //P. eumolpe//. (Photo: Jinfa©) >>>>>>>>>>>>>>>>>>>>>>>>>> Vid. 05. //P. eumolpe// circulating water around its reticulated setae. (Video: Jinfa©) > ||
 * === Reproduction ===
 * === Reproduction ===

//P. eumolpe// males have been observed to initiate coutship by waving their claws to attract females. 31] During copulation, both crabs face their ventral sides to each other and have their abdomens extended so that the male is able to insert his gonopods into the female's paired vulvae to deliver his sperm (Fig. 14 & 16; Vid. 06). 31]

media type="youtube" key="ANpaYS_eA8I" height="315" width="560"

Vid. 06. //Sesarma rectum// mating. (Video: wishikawa1)

As a result of having to extend their abdomens to mate, it has been generalized that crabs can only mate after a female has recently moulted because the abdomen of the females are inflexible during inter-moults. 31] This might not necessarily be true for Sesarmidae as studies on some of the crabs in this [|taxon] such as //Amrases ricord// have been been shown to mate during inter-moults. 31]32] This has has yet to be confirmed for //P. eumolpe//. However, the evidence of mate guarding by males might indicate that females only mate at certain stages in the moult cycle. 16]

After fertilisation, females keep the eggs in her abdomen (Fig. 15) before spawning during a high tide on full or new moon. 13] The eggs hatch out into planktonic larvae known as zoea (Fig. 31). These would then grow and moult into megalopa (Fig. 32), the final stage as a zooplankton, before they become visible miniature crabs. 27]

>>>>> Fig. 32. Crab zoea illustration. (Permission pending from Davey©) >>>> Fig. 33. Crab megalopa illustration. (Permission pending from Davey©) > ||

= Taxonomy =

Taxonavigation
> Arthropoda >> Crustacea >>> Malacostraca >>>> Eumalacostraca >>>>> Eucarida >>>>>> Decapoda >>>>>>> Pleocyemata >>>>>>>> Brachyura >>>>>>>>> Eubrachyura >>>>>>>>>> Thoracotremata >>>>>>>>>>> Grapsoidea >>>>>>>>>>>> Sesarmidae >>>>>>>>>>>>> Perisesarma >>>>>>>>>>>>>> // P. eumolpe // ||  || > Fig. 34. //P. eumolpe// hiding in a crevice. (Photo: Jinfa©) || Ranks (such as family, class, order, genus, etc.) have been omitted in the taxonavigation as they are misleading. For example, two organism with the same ranks might not have the same evolutionary history (age of origin) and thus should not be compared at that level.
 * Animalia

Taxonomic History

 * It is important to know the different names (synonyms) used for //P. eumolpe// as research on any organism is published under its species name. Thus, one could miss out information by searching with just the accepted name, as the organism might have been filed under a different name. The following paragraphs describe how the name of //P. eumolpe// has changed over the years.

//P. eumolpe// was first described by De Man and placed in the taxon // Searma (Perisesarma) //. 2] Subsequently in 1909, Rathbun substituted the name //Chiromantes// Gistel, 1848 for de Man's //Perisesarma//. 33] This resulted in Tesch revising //Sesarma (Perisesarma) eumolpe// as // Sesarma (Chiromantes) eumolpe // in 1917. 3] Thereafter, in 1967, Campbell revised //Sesarma (Chiromantes)// and designated //Sesarma dussumieri// H. Milne Edwards, 1853 as the type specimen for this group. 34]

Following in 1973, Holthuis proposed that //Chiromantes// Gistel, 1848 should be the replacement name for //Pachysoma// De Haan (1833). 35] This was because Rathbun designated //Grapsus (Pachysoma) bidens// De Haan, 1833, as the type species of //Pachysoma// incorrectly as De Haan did not originally include that species in //Pachysoma//. 35]36]37] Thus, Holthius designated //Grapsus (Pachysoma) haematocheir// De Haan, 1833 as the type specimen for //Pachysoma// De Haan, 1833. 35]

On the other hand, //(Pachysoma) haematocheir// De Haan, 1833 was also the designated type specimen of the subgenus //Holometopus// H. Milne Edwards,1853 at that time. Therefore //Chiromantes// Gistel, 1848 became a senior objective synonym of //Holometopus// H. Milne Edwards,1853. 35]

Thus, in 1973, Holthuis revised that //Chiromantes// Gistel, 1848, should be used for the taxon usually indicated as //Holometopus//, while the taxon usually indicated as //Chiromantes// should be known as //Perisesarma// De Man, 1895. He then proceeded to designate //P. eumolpe// as the type specimen for //Perisesarma//, not knowing that //Sesarma dussumieri// H. Milne Edwards, 1853 was already designated as the type specimen by Campbell in 1967. 34]35]38] Thus, the c orrect type specimen for //Perisesarma// is //Sesarma dussumieri// H. Milne Edwards, 1853. 38]

In 2001, Sesarmidae was elevated to the family level from a sub-family. Consequently, //Perisesarma// was elevated to the genus level. 39] The current taxa nested in Sesarmidae is still very messy and are being revised. 27]

For more information on how to identify P. eumolpe, refer to Description section. || <span style="font-family: Arial,Helvetica,sans-serif; font-size: 90%;"> Fig. 35. //P. eumolpe// hiding in a crevice (Photo: Jinfa & Christopher©) . Fig. 36. //P. eumolpe// tucked in a hole in a wood (Photo: J©) ||

Phylogenetics
were more closely related to one another than //P. eumolpe// is to them. On the other hand, when maximum likelihood was chosen as the selection criteria, //P. eumolpe// formed sister groups with the similarly coloured // P. samawati //. 4] This would suggest that //P. eumolpe// and //P. samawati// was more closely related to one another than to the other crabs. || Fig. 37. Phylogenetic relationships of four Indo-Pacific species of //Perisesarma// spp. based on 575 base pairs of mtDNA coding for the 16S rRNA. Maximum parsimony tree (left) and maximum likelihood (neighbour joining, Kimura 2-parameter distances) tree (right) with confidence values established after 2000 bootstrap replicates. (Figure reproduced with permission from Gillikin & Schubart, 2004) ||
 * A phylogenetic tree construction by Gillkin and Schubart gave different tree toplogies with different selection criteria, both of which had high bootstrap support values (Fig. 37). When the selection criteria was parsimony, //P. eumolpe// formed an outgroup to the other 3 species of //Perisesarma//. This would suggest that //P. samawati//, //P. guttatum// and //P. bidens//
 * [[image:taxo4254/p eumolpe bootstrap.png width="452" height="164"]][[image:taxo4254/p eumolpe kimura 2.png width="466" height="164"]]
 * A more interesting phylogenetic tree would be to consider the sympatric similiar looking //P. indiarium// in the analysis. However, GenBank does not have the sequences for me to construct the tree. ||


 * Acknowledgements **

I would like to give my thanks to Dr. Todd for introducing this crab to me.

Ze Lin for going out to Mandai to catch some crabs with me.

Paul and Wei Kit for helping me get food for the crabs.

Benjamin for helping me get food for the crabs and releasing them.

Maosheng and Christopher for helping me in taking photographs and videos.

Dr. Naruse, Dr. Gillikin, Peiya, Simon and Ria for their photographs and figures.

Sufyan for helping me troubleshoot my flash animations when they don't work as planned.

Dr. Ng for helping me with Fig. 11.

All researchers who has generated the information for me to put on this page.

Fig. 38. //P. eumolpe// hiding under a plank (Photo: Jinfa & Maosheng©)

= Comments =

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= Links =
 * * <span style="font-family: Arial,Helvetica,sans-serif; font-size: 90%;">Face-banded sesarmine crabs. Tan, Ria, 2009. [|WildSingapore.]
 * <span style="font-family: Arial,Helvetica,sans-serif; font-size: 90%;">[|Fascinating face-banded sesarmine crabs.] Tan, Ria, 6 April 2009. Wild shores of Singapore blog.
 * <span style="font-family: Arial,Helvetica,sans-serif; font-size: 90%;">[|Wild victory dance of crabs on our shores.] Tan, Ria, 11 July 2009. Wild shores of Singapore blog.
 * <span style="font-family: Arial,Helvetica,sans-serif; font-size: 90%;">[|When crabs perform their victory dance] Grace Chua, 11 July 2009. The Straits Times.
 * <span style="font-family: Arial,Helvetica,sans-serif; font-size: 90%;">[|Sesarmine crabs.] Ng, Peter K. L. & N. Sivasothi, 1999. [|A Guide to the Mangroves of Singapore II (Animal Diversity)]. Singapore Science Centre, Singapore. 168 pp.
 * <span style="font-family: Arial,Helvetica,sans-serif; font-size: 90%;">[|Sesarmine crabs (Episesarma and Chiromantes).] Tan, Leo W. H. & Ng, Peter K. L., 1988. [|A Guide to Seashore Life]. Singapore Science Centre, Singapore. 160 pp.
 * <span style="font-family: Arial,Helvetica,sans-serif; font-size: 90%;">[|GenBank DNA sequences for Perisesarma eumolpe]. ||

= Literature Cited = > ([|Online PDF] on the Flanders Marine Institute website) > ([|Online Abstract] on Wiley Online Library website ) ||
 * # <span style="font-family: Arial,Helvetica,sans-serif; font-size: 90%;">Davie, P. & Fransen, C., 2012. [|Perisesarma eumolpe (De Man, 1895)]. Accessed through [|World Register of Marine Species] on 25/10/2012.
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<span style="display: block; height: 1px; left: -40px; overflow: hidden; position: absolute; top: 5000px; width: 1px;">16. **Results from reflectance spectrometry show the differences in the intensity of reflected light measured from -60° to 60°, at 5° intervals (with down-welling light arriving from 0° to 60°, as depicted by the crab icons at the top of the graph). The facial bands collected and reflected most light towards the 0° to 10° sector (highlighted in the coloured strips).**