<Tr> <Td> Chordata </Td> </Tr> <P> The number of described vertebrate species are split evenly between tetrapods and fish . The following table lists the number of described extant species for each vertebrate class as estimated in the IUCN Red List of Threatened Species, 2014.3 . </P> <Table> <Tr> <Th_colspan="3"> Vertebrate groups </Th> <Th> Image </Th> <Th> Class </Th> <Th> Estimated number of described species </Th> <Th> Group totals </Th> </Tr> <Tr> <Th> Anamniote lack amniotic membrane so need to reproduce in water </Th> <Th> Jawless </Th> <Th> Fish </Th> <Td> </Td> <Td> Myxini (hagfish) </Td> <Td> </Td> <Td> 32,900 </Td> </Tr> <Tr> <Td> </Td> <Td> Hyperoartia (lamprey) </Td> <Td> </Td> </Tr> <Tr> <Th> Jawed </Th> <Td> </Td> <Td> cartilaginous fish </Td> <Td> </Td> </Tr> <Tr> <Td> </Td> <Td> ray - finned fish </Td> <Td> </Td> </Tr> <Tr> <Td> </Td> <Td> lobe - finned fish </Td> <Td> </Td> </Tr> <Tr> <Th> Tetrapods </Th> <Td> </Td> <Td> amphibians </Td> <Td> 7,302 </Td> <Td> 33,278 </Td> </Tr> <Tr> <Th> Amniote have amniotic membrane adapted to reproducing on land </Th> <Td> </Td> <Td> reptiles </Td> <Td> 10,711 </Td> </Tr> <Tr> <Td> </Td> <Td> birds </Td> <Td> 10,425 </Td> </Tr> <Tr> <Td> </Td> <Td> mammals </Td> <Td> 5,513 </Td> </Tr> <Tr> <Td_colspan="6"> Total described species </Td> <Td> 66,178 </Td> </Tr> </Table> <Tr> <Th_colspan="3"> Vertebrate groups </Th> <Th> Image </Th> <Th> Class </Th> <Th> Estimated number of described species </Th> <Th> Group totals </Th> </Tr>

In addition to fishes the subphylum vertebrata includes