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Desis martensi (L. Koch, 1872)


Desis martensi, commonly known as the reef spider or marine spider, is a marine spider that can be found along the intertidal zones of Singapore. It was first described by Dr. Ludwig Carl Christian Koch in 1872. 1

Figure 1: Desis martensi specimens observed on St John's Island in Singapore.

Photo credit: Kieron Gabriel Ng.

Description


Desis martensi adults are usually 

Etymology


The species is named after German marine zoologist Dr Eduard von Martens, who discovered and collected the species in Singapore in 1861. It was then described by German entomologist and arachnologist Dr. Ludwig Carl Christian Koch in 1872. 3

Habitat


Desis martensi can be found in the inter-tidal zone, in habitats such as rocky shores or coral reefs, hiding inside hollow corals or rocks which they seal up using waterproof silk during high tide.4 During low tide, they are often found scurrying around the surface of corals or rocks, or scuttling across the water surface. They retreat back into their nests during high tide.3

Like all spiders, Desis martensi also possesses spinnerets and is able to spin webs. However, rather than for prey capture, Desis martensi utilize their webs to line the inside and outside of their nests in corals or rocks. 3

Furthermore, although Desis martensi is found in the intertidal habitat, and is considered to be a marine spider, it does not have the ability to respire through seawater like most other aquatic arthropods do. Thus it relies on creating air pockets in hollow rocks or corals with waterproof webbing in order to survive high tide.3 5

Figure 4: Video of active Desis martensi specimens observed on St John's Island in Singapore.

Video credit: Kieron Gabriel Ng.

Distribution


Desis martensi is native to Singapore. However, it has been found recently along some coastlines in indonesian archipelago.

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Google maps of sightings

Conservation


Status

Desis martensi has not yet been evaluated by the IUCN red list.

However, it is listed as 'Vulnerable' in the Singapore Red Data Book 2008. 6 The main threats to Desis martensi populations include land reclamation and beach enhancement projects.2

Importance

Very few scientific studies have been conducted on Desis martensi. However, it holds great scientific importance as one of the few marine spider species present, and insights could also be gleamed from studying it's developmental processes or morphological adaptations to surviving in the intertidal habitat. 7

Biology


Feeding Habits

Desis martensi have been observed to consume small marine invertebrates the are abundant across the intertidal zone, such as sea slaters or shrimp (Figures 4 and 5). It has also been observed venturing onto the shore to hunt prey such as crickets (Figure 6).  8 They have also been observed to consume amphipods and small crabs. 4

Locomotion

They move about like normal spiders on solid substrate or in shallow water. However, they have been observed to jump from rock to rock if the tide gets too high. 4 Desis martensi are able to effortlessly skate across the surface of the water due to the presence of long hairs on each of their legs that prevent them from breaking the surface tension of the water (Figure 7).9

Reproduction

Desis martensi spin waterproof silk cocoons and seal their eggs inside them.

Mating positions (diagram)10

Diagnostic


How to differentiate this species from the rest

very hairy

Aka use species concepts

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Type Information


The type specimen was collected from Singapore; on coral reefs surrounding the land mass that is now known as Sentosa.7

Phylogeny


Desis martensi is situated in the family Desidae (Walckenaer, 1837).11 Recently, Wheeler et al., 2017 found that the genus Desis was quite distinct, and was the most divergent, from the other genera in the family Desidae (e.g. compared to sister groups Barahna and Poaka). 12 The family Desidae is also one of the more broadly circumscribed and less well supported spider families despite years of effort and study by scientists.12

References



Footnotes
Ref Notes
1 Koch, L. (1872). Desis martensi. In Die Arachn(pp. 347). Austral.
2 Davison, G. W. H., Ng, P. K. L. & Ho, H. C. (2008). The Singapore Red Data Book (2nd Edition). Singapore: Nature Society (Singapore). 285pp [ a b ]
3 Pocock, R. I. (1833). On the Marine Spiders of the Genus Desis with Description of a new Species. In Proceedings of the Zoological Society of London(pp. 98-106). London: London Academic Press. [ a b c d ]
4 Bristowe, W. (1931). LXI.—Notes on the biology of spiders.—IV. Further notes on aquatic spiders, with a description of a new species of Pseudoscorpion from Singapore. Annals and Magazine of Natural History,8(47), 457-465. doi:10.1080/00222933108673422 [ a b c ]
5 Tan, R. (2016). Marine Spider. Retrieved November 15, 2018, from http://www.wildsingapore.com/wildfacts/arachnida/desis.htm
6 Davison, G. W. H., Ng, P. K. L. & Ho, H. C. (2008). The Singapore Red Data Book (2nd Edition). Singapore: Nature Society (Singapore). 285pp
7 Nparks Flora & Fauna Web. (2013). Desis martensi L. Koch, 1872. Retrieved November 15, 2018, from https://florafaunaweb.nparks.gov.sg/special-pages/animal-detail.aspx?id=353 [ a b ]
8 Tan, R. (2016). Marine Spider. Retrieved November 15, 2018, from http://www.wildsingapore.com/wildfacts/arachnida/desis.htm
9

Bristowe, W. (1931). LXI.—Notes on the biology of spiders.—IV. Further notes on aquatic spiders, with a description of a new species of Pseudoscorpion from Singapore. Annals and Magazine of Natural History,8(47), 457-465. doi:10.1080/00222933108673422


10 Bristowe, W. S. (1931). 68. The Mating Habits of Spiders: A Second Supplement, with the Description of a New Thomisid from Kritkatau. Proceedings of the Zoological Society of London,101(4), 1401-1412. doi:10.1111/j.1096-3642.1931.tb01070.x
11 Walckenaer, C. A. (1837). Histoire naturelle des insectes. Aptères. Paris 1, 1-682.
12 Wheeler, W. C., Coddington, J. A., Crowley, L. M., Dimitrov, D., Goloboff, P. A., Griswold, C. E., Hormiga, G., Prendini, L., Ramírez, M. J., Sierwald, P., Almeida-Silva, L. M., Álvarez-Padilla, F., Arnedo, M. A., Benavides, L. R., Benjamin, S. P., Bond, J. E., Grismado, C. J., Hasan, E., Hedin, M., Izquierdo, M. A., Labarque, F. M., Ledford, J., Lopardo, L., Maddison, W. P., Miller, J. A., Piacentini, L. N., Platnick, N. I., Polotow, D., Silva-Dávila, D., Scharff, N., Szűts, T., Ubick, D., Vink, C., Wood, H. M. & Zhang, J. X. (2017). The spider tree of life: phylogeny of Araneae based on target-gene analyses from an extensive taxon sampling. Cladistics 33(6): 576-616. doi:10.1111/cla.12182 [ a b ]














Figure 2: Desis martensi specimen observed on a coral on Lazarus Island. Photo credits: Ria Tan. Permission Granted


Figure 3: Desis martensi specimen observed on a seagrass bed on St John's Island. Photo credits: Ria Tan. Permission Granted

















































Figure 4: Desis martensi specimen eating a shrimp on Kusu Island. Photo credits: Ria Tan. Permission Granted


Figure 5: Desis martensi specimen eating a sea slater in Sentosa (Tanjung Rimau). Photo credits: Ria Tan. Permission Granted


Figure 6: Desis martensi specimen eating a cricket on Kusu Island. Photo credits: Ria Tan. Permission Granted


Figure 7: Desis martensi skating across the surface of the water at Cyrene reef. Photo credits: Ria Tan. Permission Granted

This page was authored by Ng Weng Loong Kieron Gabriel (kieron_gabriel@yahoo.com)
Last curated on 15th November 2018

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