检查语法是否正确，请修改目前地球上已知的动物大约有150万种。 动物可分为脊椎动物和无脊椎动物两大类世界上也还有许多种动

检查语法是否正确，请修改
目前地球上已知的动物大约有150万种。
动物可分为脊椎动物和无脊椎动物两大类世界上也还有许多种动物还未被发现1.Currently the animal on the earth is known about 150 million.
Animals can be divided into vertebrates and invertebrates two categoriesThe world also have many species of animals that have not yet been discovered. 2.At present on the Earth the known animal probably has 1,500,000 kinds. the animal may divide into the vertebrate and non-vertebrate two broad heading in the world also has many kind of animals not to discover 3.Currently known animals on Earth about 150 million. Animals can be divided into two major categories of vertebrates and invertebrates in the world there are still many undiscovered species of animals has also 意思应该都一样，哪个更正确，改正一下（至少也会有些错误吧）