The elephant shark is a cartilaginous fish (a group which includes sharks, rays, skates and others), the oldest living group of jawed vertebrates. They possess complex physiological systems such as a central nervous system, adaptive immune system, circulatory system and neuroendocrine system that are typical of vertebrates. The elephant shark grows to a length of 60 to 120 centimeters. They are often commercially exploited for fillets at fish-and-chips restaurants in Australia and New Zealand. Mature adults migrate into large estuaries and inshore bays for spawning during spring and summer. Females lay eggs on sandy or muddy substrates. The egg cases are large, about 25 cm long and 10 cm wide. Like shark and skate eggs, elephant shark eggs take 6 to 8 months to hatch.
The elephant shark (also known as ‘elephant fish,’ ‘ghost shark,’ ‘reperepe’ and ‘whitefish’) is a cartilaginous fish that is native to New Zealand and southern Australia and is generally found in subtropical waters at depths of at least 200 meters. It tends to dwell in rivers with soft or muddy bottoms.
The elephant shark has a very compact genome (estimated to be less than 1 Gb), and sequencing it provides an economically feasible and high-quality representation of the cartilaginous fish genome. Due to the elephant shark’s age, sequencing its genome helps shed light on the evolution of the vertebrate genome. We generated 2x sequence coverage from the ends of plasmids (3-12 kb) and fosmids and combined these with ~12x coverage of 454 fragment and 3 and 8kb paired end sequences. A CABOG assembly has been created from all reads. The project was initiated by Dr. Venkatesh Byrappa at Singapore’s Agency for Science, Technology and Research and was a collaboration between scientists at the Institute of Molecular and Cell Biology, Singapore, and the J. Craig Venter Institute.