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Phylogenetic Systematics and Evolution

Evolution of deep sea fishes

A study of lanternfishes (Myctophiformes)

Naturalists used to think that life was impossible at water depths below 5000 m. We now know that there is plenty of life  in the deep oceans and, in spite of the difficulties of working there, new organisms are constantly being discovered  at great depths. Deep sea (>1000 m) fishes often have evolved bizarre and marvelous colors and shapes compared to their closest relatives in more moderate depth ranges. Among some of the adaptations that fish in the deep ocean display are large teeth and eyes, transformed fin rays with light emission, light organs of all imaginable shapes, jaws longer than the body and abdominal fins converted into bone and taste organs. We do not know much about how different groups of fish have evolved. This study focuses on lantern fishes (pictured), which are both mesopelagic (200-1000 m) and genuine deep sea fish. Approximately 250 species have been described, often defined by their patterns of light organs on the body. Identification of the species may be difficult  because  scales and light organs are easily damaged in catches. However, the evolution of light organs and the diversification of species are very interesting phenomena that may be studied with phylogenetic and comparative methods.

We will make a first attempt ot infer the relationship of lantern fishes using DNA sequences from the mitochondrial genomes. The project is conducted by Jan Yde Poulsen (fellow) in co-operation with Japanese ichthyologists and Bergen Museum, represented by Ingvar Byrkjedal (supervisor) and Endre Willassen (co-supervisor).