![]() Embryonic notochord tissue can also contribute to the soft tissue of intervertebral discs in vertebrates. Steve WingĪ narrow canal in each vertebra. In basal chordates such as lancelets and hagfishes, the notochord persists in the adult, as it does in the tuatara and geckoes, in which it is reduced to a thin, continuous strand that passes throughĬommon hagfish Eptatretus cirrhatus. We chordates derive our phylum name from one of our common features, the notochord (Greek notos, back chorde, cord), a somewhat flexible rod-like structure running along the length of the body – at least in all chordate embryos, for in most adult vertebrates the notochord is much reduced or absent and replaced by the vertebral column (backbone). The region has been isolated from other landmasses for 80 million years and has evolved a distinctive fauna, with terrestrial and freshwater vertebrates and a number of marine fishes showing a high degree of endemism. The EEZ extends over 30 degrees of latitude for a distance of 3,000 kilometres, 30 degrees of longitude for 2,250 kilometres, and has an area of over four million square kilometres. New Zealand lies in the Southwest Pacific Ocean across the joint margins of the Pacific and Indo-Australian lithospheric plates. Many lizard species are unnamed and, in recent years, new discoveries of fishes in the Exclusive Economic Zone (EEZ) have been at the rate of about one per fortnight, mostly from deep water. Taxonomic knowledge of the fauna is incomplete. On the other hand, New Zealand has a rich and diverse fauna of whales and dolphins. For example, native land mammals are extraordinarily depauperate – just three species of bats – whereas the bird fauna evolved to fill some of the niches left vacant by mammals. As this chapter will explain, New Zealand’s native chordates have some unusual attributes compared to those in many other countries. Depending on our interests and occupations, these are the creatures we farm, hunt, and fish, or just simply enjoy for their own sakes, such as the birds in our forests and backyards, and the seals and dolphins of our coasts. ![]() ![]() Ranging in size from an eight-millimetre-long Asian minnow to the largest animal ever to have lived (blue whale), chordates occupy most environments and have achieved a remarkable range of body form and neural development. ![]() He chordates include the largest and brainiest creatures on Earth. CHORDATA lancelets, fishes, amphibians, reptiles, birds, mammals Carolyn M. ![]()
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