<Tr> <Td> </Td> <Td> ↳ </Td> <Td> Nemertea (Nemertina) </Td> <Td> 1,200 </Td> <Td> 5,000 - 10,000 </Td> </Tr> <Tr> <Td> </Td> <Td> ↳ </Td> <Td> Rotifera </Td> <Td> 2,180 </Td> <Td> - </Td> </Tr> <Tr> <Td> </Td> <Td> ↳ </Td> <Td> Gastrotricha </Td> <Td> 400 </Td> <Td> - </Td> </Tr> <Tr> <Td> </Td> <Td> ↳ </Td> <Td> Kinorhyncha </Td> <Td> 130 </Td> <Td> - </Td> </Tr>

How many species on earth have been named