|Australian ghostshark at the Melbourne Aquarium|
Bory de Saint-Vincent, 1823
The Australian ghostshark, Callorhinchus milii, is a cartilaginous fish (Chondrichthyes) belonging to the subclass Holocephali (chimaera). Sharks, rays and skates are the other members of the cartilaginous fish group and are grouped under the subclass Elasmobranchii. Alternative names include elephant shark, makorepe, whitefish, plownose chimaera, or elephant fish.
It is found off southern Australia, including Tasmania, and south of East Cape and Kaipara Harbour in New Zealand, at depths of 0 - 200 m. Their length is up to 120 cm. Males of this species mature at about 65 cm. From spring to autumn, adults migrate inshore to estuaries and bays and females lay their eggs on sandy or muddy substrates. The eggs are contained in large yellowish capsules. The egg partially opens enabling seawater to flow in to the egg capsules after a few months and juveniles emerge from the capsule after six to eight months as about 12 cm in length. In New Zealand, Australian ghostsharks are exploited commercially, particularly during spring and summer when they migrate into shallow coastal waters. In Australia, they are caught by southern shark gillnet fishery, particularly in Bass Strait and south-east Tasmania, though this fishery targets the gummy shark, Mustelus antarcticus, and will sometimes discard ghostsharks due to the considerably lower price they fetch at market. They are also a popular target of recreational fishers in Westernport Bay, Victoria and in the inshore waters of south-east Tasmania. Their white flesh fillets are very popular with ‘fish-and-chips’ restaurants in New Zealand, but less so in Australia.
Recently, the Australian ghostshark was proposed as a model cartilaginous fish genome because of its relatively small genome size. Its genome is estimated to be 910 megabases long, which is the smallest among all the cartilaginous fishes and one-third the size of the human genome (3000 Mb). Because cartilaginous fishes are the oldest living group of jawed vertebrates, the Australian ghostshark genome will serve as a useful reference genome for understanding the origin and evolution of vertebrate genomes including humans, which shared a common ancestor with the Australian ghostshark about 450 million years ago. Interestingly, studies so far have shown the sequence and the gene order ("synteny") are more similar between human and elephant shark genomes than between human and teleost fish genomes (pufferfish and zebrafish), though humans are more closely related to teleost fishes than to the Australian ghostshark. Recently, an Elephant Shark Genome Project has been launched to sequence the whole genome of the elephant shark.
- "Boy hospitalised by fish spike". The New Zealand Herald. Retrieved April 13, 2012.
- Reardon et al. (2003). Callorhinchus milii. 2006. IUCN Red List of Threatened Species. IUCN 2006. www.iucnredlist.org. Retrieved on 12 May 2006. Database entry includes justification for why this species is of least concern
- "Callorhinchus milii". Integrated Taxonomic Information System. Retrieved 19 March 2006.
- Froese, Rainer and Pauly, Daniel, eds. (2006). "Callorhinchus milii" in FishBase. January 2006 version.
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- Venkatesh B, Kirkness EF, Loh YH, Halpern AL, Lee AP, et al. (2007) Survey Sequencing and Comparative Analysis of the (Callorhinchus milii) Genome. PLoS Biol 5(4): e101 doi:10.1371/journal.pbio.0050101
- sequencing project Institute of Molecular and Cell Biology (Singapore) at