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5 Posts tagged with the fish tag

Ellie Adamson,   Department of Life Sciences, NHM


Wednesday 11 June 11:00


Earth Sciences (Mineralogy) Seminar Room, Basement, WEB 05



Freshwater habitats in tropical Asia are home to many interesting endemic freshwater fishes. Their diversification history is frequently explained in terms of eustacy and past river geomorphology.


This talk will discuss vicariant patterns in fishes across freshwater habitats from India to Wallace’s line, based on the distribution of their genetic diversity. In particular, I’ll focus on the biogeography of snakeheads and gouramis.


More information on attending seminars at


Miniatures, morphology and molecules: problems with the phylogenetic position of Paedocypris



miniture fish.jpg



Ralf Britz

Vertebrates Division, Dept. Life Sciences, NHM


Wednesday 26 June 11:00

Sir Neil Chalmers seminar room, Darwin Centre LG16 (below Attenborough studio)


The highly miniaturized fish species of the cyprinid genus Paedocypris are among the smallest of all vertebrates. Their skeleton shows a puzzling mixture ofhighly reductive and morphologically novel characters. Numerous structures present in most bony fishes are absent in Paedocypris due to an organism wide case of progenesis or developmental truncation. I highlight the problems associated with working morphologically with such a truncated organism and offer some solutions. I also look in detail at the evidence from recent molecular systematic analyses some of which are in sharp contrast to the results based on morphology. I touch upon the general issue of morphology versus molecules and discuss it in the context of the phylogenetic position of Paedocypris.


For additional details on attending this or other seminars see


Ralf Britz and his Smithsonian colleague David Johnson have published a paper in the Journal of Morphology on the development of the sucking disc of remoras. Remoras are a group of marine fish that usually attach themselves to sharks or other large fish such as manta rays with their sucking disc.  This lifestyle appears not to harm the shark, nor does it bring any benefit: depending on the species of remora, they eat fragments of the larger fish's food that fall from its mouth;  faeces; or the larger fish's parasites.


Echeneis NaturalHistoryMuseum_PictureLibrary_009079_Comp.jpgEcheneis naucrates - watercolour painting by Sydney Parkinson made during Captain Cook's first voyage 1768-1771


Ralf's work on the sucker involved examination and comparison of fins of different species of fish to identify the homology of its components - homology is the term used to describe organs in two species that have the same evolutionary origin, despite sometimes different appearance and function (so the human arm and a bat's wing are homologous).  The remora's sucker is not found in other fish - is it a totally new organ, or is it a highly modified version of an organ found in other fish?


By studying the development of larval remoras ranging from 9.3 to 26.7 mm in length, they demonstrated that the skeleton of the sucking disc forms by enormous expansion of the dorsal fin supports and the bases of the associated fin spines. The evolution of a sucking disc from a regular spinous dorsal fin seems like a major step in evolution but is actually a gradual process involving small incremental changes of structures during development.

Britz, R. & G. D. Johnson. 2012. Ontogeny and homology of the skeletal elements that form the sucking disc of remoras (Teleostei, Echeneoidei, Echeneidae). Journal of Morphology, 273 (12) 1353-1366 , DOI: 10.1002/jmor.20063

Ralf has also published a paper with a Brazilian colleague, Mônica Toledo-Piza, analysing the egg surface structure of the poorly known and highly venomous freshwater toadfish Thalassophryne amazonica with the NHM's scanning electron microscopes (SEM). Eggs of this fish show a highly unusual and complex system of ridges and intermittent grooves that originate at the equator of the egg and run toward the animal egg pole and end in a spiraling pattern at the micropyle (the only opening for sperm to enter). This striking modification may help to increase the chances of eggs being fertilized.

Britz, R. & M. Toledo-Piza. 2012. Egg surface structure of the freshwater toadfish Thalassophryne amazonica (Teleostei: Batrachoididae) with information on its distribution and natural habitat. Neotropical Ichthyology, 10: 593-599.


Ralf Britz and collaborators from the Conservation Research Group from St Albert's College, Kochi, Kerala have published a series of papers describing three new fish species from South India.


Pristolepis rubripinnis, Dario urops and Pangio ammophila were discovered during the January 2012 NHM-funded visit of Dr Ralf Britz to Kochi, to work with Dr Rajeev Raghavan. Historical specimens of the fish collection in the Natural History Museum collected by Sir Francis Day in the 1860s and 70s played an important role in the resolution of taxonomic and nomenclatural issues before the species could be described.


This series of papers highlights our incomplete knowledge of one of the most important biodiversity hotspots in Asia, the Western Ghats, a mountain range along the west coast of Peninsular India. Both Pristolepis rubripinnis and Dario urops are of particular interest in that closely related species are found in north-eastern India - it is not clear how this distribution arose because there are no river connections between the two areas that would have allowed ancestral populations to separate, migrate and diverge into different species. 

Britz, R., Kumar, K. & Baby, F. (2012). Pristolepis rubripinnis, a new species of fish from southern India (Teleostei: Percomorpha: Pristolepididae). Zootaxa, 3345: 59-68.

Britz, R., Ali, A. & Philip, S. (2012). Dario urops, a new species of badid fish from the Western Ghats, southern India (Teleostei: Percomorpha: Badidae). Zootaxa, 3348: 63-68.

Britz, R., Ali, A. & R. Raghavan. (2012). Pangio ammophila, a new species of eel-loach from Karnataka, southern India (Teleostei: Cypriniformes: Cobitidae). Ichthyological Exploration of Freshwaters, 23: 45-50.


Fin loss in a spiny eel

Posted by John Jackson Jul 19, 2011

Vertebrates - mammals, birds, fish and amphibians - have broadly the same body plan with two pairs of limbs.  However, over time, some species and groups have lost one or both pairs of limbs.  Many others have reduced limbs.  Whales, snakes, caeclian amphibians and a range of fish are some of the examples.


Modern scientific research has a strong interest both in the patterns of development and in how and why these change as a result of genetic evolution - it does appear that different genes can be involved in limb reduction and loss in different groups. 


Drs Ralf Britz and Lukas Rüber (NHM Zoology) and colleagues from University College London and the South African Institute for Aquatic Biodiversity, Grahamstown reported the first case of pectoral fin loss in the Mastacembelidae (Teleostei: Synbranchiformes) with the discovery of a new species of spiny eel from Lake Tanganyika in the Journal of Zoology.


A previous evolutionary phylogeny of mastacembelids using comparisons of genetic differences between different species,  coauthored by Dr Rüber , had placed the new species Mastacembelus apectoralis sp. nov. within the Lake Tanganyikan species flock, having diverged from its sister species M. micropectus around 4.5 million years ago. M. micropectus also shows a reduction in the size of its pectoral fin and endoskeletal girdle, and has largely cartilaginous pectoral radials and a reduced number of pectoral-fin rays. This is in contrast to the bony skeletons of most fish species in this group


The loss of pectoral fins and reduction of associated girdle elements in M. apectoralis represent another independent occurrence of this evolutionary phenomenon within teleosts. The discovery of this species highlights the exceptional diversity of the biodiversity hotspot, Lake Tanganyika, the understanding of which is of critical importance with the pressures of pollution, overfishing and climate change threatening the speciose and evolutionarily significant diversity of this ancient lake.

Brown, K. J., Britz, R., Bills R., Rüber, L. & Day J. J. (2011). Pectoral fin loss in the Mastacembelidae: a new species from Lake Tanganyika. Journal of Zoology April 2011 doi:10.1111/j.1469-7998.2011.00804.x