New Zealand hagfish
| New Zealand hagfish | |
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| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Myxini |
| Order: | Myxiniformes |
| Family: | Myxinidae |
| Genus: | Eptatretus |
| Species: | E. cirrhatus |
| Binomial name | |
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Eptatretus cirrhatus (J. R. Forster, 1801) |
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The New Zealand hagfish, Eptatretus cirrhatus, is a hagfish found around New Zealand and the Chatham Islands as well as around the south and east coasts of Australia, at depths between 1 and 900 metres.
Eptatretus cirrhatus, more commonly known as the New Zealand hagfish or the Broadgilled hagfish has an eel-like body with no dorsal fin, a paddle-like tail and are often a grey-brown with a pink or bluish tinge of colour. Hagfish are an ancient species that evolved around 300 million years ago and have changed little since then. It is believed that hagfish share a joint ancestor with vertebrates (Zintzen et al., 2011). Although you cannot tell, the hagfish does have eyes but they are underdeveloped and covered by several layers of skin making it not visible externally (Cosidine, 1995), which is why it is also sometimes called the blind eel. The New Zealand hagfish has a skull but no jaw or true vertebral column, it instead has a skeleton made up of cartilage. The rounded mouth of the hagfish is surrounded by 6 barbels, above that is their singular nasal passage and just inside the mouth is a dental plate with a row of posterior and anterior keratinous grasping teeth on each side (Clark & Summers, 2007). It has seven pairs of gill pouches and forming a line down both the lower sides of its body are pores which often many of the are ringed with a white colour and are used for secreting a snot-like slime which expands out once it has contact with the sea water. Juveniles are lighter in colour.
General hagfish are found around the world in waters below 22 degrees Celsius. E. cirrhatus has a range that includes the western pacific and stretches down the east coast of Australia from Queens land to Tasmania as well as throughout New Zealand from the North Cape to Snares Shelf and around the Chatham Islands.
E. cirrhatus is found in coastal areas of New Zealand in shelf and slope areas along the coast with frequent sighting in Kaikoura. It is also found on rises and banks out in the open ocean. Their New Zealand range includes the Chatham Islands.
The New Zealand Hagfish is common throughout the temperate coastal shelves, in depths ranging between 1m and 900m. The hagfish is most common between 90 and 700m. “All known Hagfish species live in close proximity to the bottom, either resting on the substrate or occupying burrows ”
In a study done on the reproductive stages, there was no indication found that Eptatretus cirrhatus breeds cyclically or seasonably as females with large eggs present and postovulatory females were found throughout all seasons of the study. It was suggested that the first female spawning is thought to occur when the total length is between 412mm – 534mm, while Males are thought not to mature until they are about 585mm in length. Not much is yet understood about the gestation period of the Eptatretus cirrhatus but they did find a low reproductive rate occurring and therefore issues may arise from commercial fisheries, although they are currently at a ‘least concern’ IUCN It can take up to 2 or 3 years after maturing for hagfish to produce only 20–30 eggs. Embryo development is slow with early stages developing at only 7 months in some species of hagfish. “The ovary is found in the anterior portion of the gonad, and the testis is found in the posterior part.” indicates four outcomes can happen during development that determines the sex of an individual. If the anterior part develops then the individual is female if the posterior part develops the individual is male. If neither develops the individual becomes sterile. If the individual develops both then the individual become a hermaphrodite, research is currently being undertaken to determine where hermaphrodites are to be considered functioning or not.
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Wikipedia