Mudskipper

Mudskippers

Periophthalmus modestus: SUMA Aqualife Park (Japan)

Periophthalmus gracilis (from Malaysia to NAustralia)

Many marine fish live in intertidal habitats, surviving the retreat of the tide by hiding under wet seaweed or by using temporary tide pools. Mudskippers instead, gobies of the subfamily Oxudercinae, are uniquely adapted to a completely amphibious lifestyle (Murdy, 1989). Mudskippers are found only in tropical and subtropical regions, having a geographical distribution that includes all the Indo-Pacific and the Atlantic coast of Africa. Mudskippers are very active when out of water, feeding and interacting with one another, for example to defend their territories.

Mudskippers display a range of behavioural and physiological adaptations. Compared with normal, fully aquatic gobies, these include:

• Anatomical and behavioural adaptations that allow them to move effectively on land as well as in the water (Harris, 1961).
• The ability to breathe through their skin and also through the lining of the mouth (the mucosa) and throat (the pharynx). This is only possible when the mudskipper is wet, limiting mudskippers to humid habitats and requiring that they keep themselves moist. This mode of breathing, similar to that employed by amphibians, is known as cutaneous breathing (Graham, 1997).
• Digging of deep burrows in soft sediments that allow the fish to thermoregulate; avoid marine predators during the high tide when the fish and burrow are submerged; and for laying their eggs (Sasekumar et al., 1994; Tytler & Vaughan, 1983; Brillet, 1969).

Even when their burrow is submerged, mudskippers maintain an air pocket inside it, which allows them to breathe in conditions of environmental very low oxygen concentration (Ishimatsu et al., 1998; 2000; Lee et al., 2005).

The diverse and widespread genus Periophthalmus is by far the most diverse genus of mudskipper. Seventeen species are currently recognised (Larson & Takita, 2005). Periophthalmus argentilineatus is one of the most widespread and well known mudskippers. This species can be found in mangrove ecosystems and mudflats of East Africa and Madagascar east through South East Asia to Northern Australia, Hong Kong and Southern Japan, up to Samoa and Tonga Islands (Murdy, 1989). It grows to a length of about 6 in (15 cm) and is a carnivorous opportunist feeder. It feeds on small preys such as small crabs and other arthropods (Milward, 1974). Another species, Periophthalmus barbarus, is the only oxudercine goby that inhabits the coastal areas of Western Africa (Murdy, 1989). Both these mudskippers are widely traded as aquarium fish.

References

• Brillet C., 1969. Etude du comportement constructeur des poissons amphibies Periophthalmidae, Terre et la Vie, 23 (4): 496–520.
• Graham J.B., (editor) 1997. Air–breathing Fishes. Evolution, Diversity and Adaptation, Academic Press, San Diego California, 299 pp.
• Harris V.A., 1961. On the locomotion of the mudskipper Periophthalmus koelreuteri (Pallas): Gobiidae, Proceedings of the Zoological Society of London, 134: 107-135.
• Ishimatsu A., Hishida Y., Takita T., Kanda T., Oikawa S., Takeda T. & Khoo K.H., 1998. Mudskipper Store Air in Their Burrows, Nature, 391: 237–238.
• Ishimatsu A., Takeda T., Kanda T., Oikawa S. & Khoo K.H., 2000. Burrow environment of mudskippers in Malaysia. Journal of Bioscience, 11 (1,2): 17–28.
• Larson H.K. & Takita T., 2005. Two new species of Periophthalmus (Teleostei: Gobiidae: Oxudercinae) from northern Australia, and a re-diagnosis of Periophthalmus novaeguineaensis. The Beagle, Records of the Museums and Art Galleries of the Northern Territory, 20: 175-185.
• Lee H.J., Martinez C.A., Hertzberg K.J., Hamilton A.L. & Graham J.B., 2005. Burrow air phase maintenance and respiration by the mudskipper Scartelaos histophorus (Gobiidae: Oxudercinae). The Journal of Experimental Biology, 208: 169-177.
• Milward N.E., 1974. Studies on the taxonomy, ecology and physiology of Queensland mudskippers, unpub. Ph D. dissertation, Univ. Of Queensland, Brisbane, Australia, 276 pp.
• Murdy E.O., 1989. A Taxonomic Revision and Cladistic Analysis of the Oxudercine Gobies (Gobiidae: Oxudercinae) – Records of the Australian Museum, Suppl. N°11: 1–93.
• Murdy E.O., Takita T., 1999. Periophthalmus spilotus, a new species of mudskipper from Sumatra (Gobiidae: Oxudercinae). Ichthyological Research, 46 (4): 367–370.
• Sasekumar, A.; Chong, V.C.; Lim, K.H. & Singh, H.R., 1994. The Fish Community of Matang Mangrove Waters, Malaysia – Sudara, S.; Wilkinson, C.R.; Chou, L.M. (eds). Proceedings, Third ASEAN-Australia Symposium on Living Coastal Resources. Research papers. Chulalonghorn University, Bangkok, Thailand. Vol. 2: 457-464.
• Tytler P. & Vaughan T., 1983. Thermal Ecology of the Mudskippers Periophthalmus koelreuteri (Pallas) and Boleophthalmus boddaerti (Pallas), of Kuwait Bay. Journal of Fish Biology, 23 (3): 327–337.

External link

• FishBase entry on Gobiidae
• Gobioid Research Institute
• Encyclopaedia of Goby (mostly Japanese)
• Themudskipper.org: a website on mudskippers
• Mudskipper & Goby Page for aquarists
• Yahoo gobygroup: a mailing list on gobies, primarily for aquarists