Debora Semonich, age 11, of Bridgeport, Connecticut, for her question:
How many animal species are there altogether?
We can estimate the number of known animal species but a total figure is impossible because we can't count the unknoxms. Vlhat's more, when Andy says that there are at least a million known species, it does not mean that your faithful reporter is shirking his homework. Far from it. The .fabulous sciences are very. complex and the work of science researchers is very involved. Naturally you hope for an exact figure but this is too much to expect. 'Neat and easy answers are rare and hard to find and usually inaccurate.
Some authorities estimate the number of known animal species to be as high as one and a quarter million. Others give an even higher figure. host stay on the safe side and say that there are at least one million. None of these answers is lazy or sloppy and certainly there is no intention to be dishonest.
Nobody can give a perfectly precise count because, for one thing, more species are discovered continuously. What's more, identification and classification call for highly complicated skills. Sometimes it takes teams of international experts many months to classify a strange animal. For one thing, they have to verify the fact that he is not a slightly different strain of a species already known.
It would be nice to know each and every animal species that shares our planet, plus his precise role in our luxurious global ecology. But perhaps it is more rewarding to know something about their different types and categories. Scientists have a splendid system of classification that identifies and also reveals a great deal about the nature of the earth's various living animals.
The major categories are phyla, plural of phylum. The most familiar group is the vertebrates of the Phylum Chordata. More than 30,000 of these backboned animals are fishes and more than 9,000 are birds. The group also includes about 6,000 cold blooded reptiles, including the snakes, and 5,000 warm blooded mammals, furry creatures who give birth to live young and feed their babes on mother's milk.
The largest group by far is the Order Insecta, a group in the huge Phylum Arthropods. More than 800,000 known insect species have been identified but experts estimate that several hundred thousand remain on the long list of unknowns.
Nobody knows how many one celled animals of the Phylum Protozoa are waiting to be discovered. There are 100,000 known octopus and oyster types of the mollusk group ¬and 1,000 or so new species are identified every year.
Large numbers of unfamiliar animals are modest little spineless creatures. They include corals and other polyps, the jellyfish and starfish groups, plus assorted groups of secretive roundworms, flatworms and ribbon worms. There are other, but let's not forget the almost 5,000 or so sponge animals of the porous Phylum Porifera.