Diversity
At all taxonomic levels, gastropods are second only to the insects in terms of their diversity.
Gastropods are the class of molluscs which have the greatest numbers of named species. However estimates of the total number of gastropod species vary widely, depending on the cited sources. The number of gastropod species can be ascertained from estimates of the number of described species of Mollusca with accepted names: about 85,000 (minimum 50,000, maximum 120,000). But an estimate of the total number of Mollusca, including undescribed species, is about 240,000 species. The estimate of 85,000 molluscs includes 24,000 described species of terrestrial gastropods.
Different estimates for aquatic gastropods (based on different sources) give about 30,000 species of marine gastropods, and about 5,000 species of freshwater and brackish gastropods. The total number of recently discovered species of freshwater snails is about 4,000.
There are 444 recently extinct species of gastropods (extinct since the year 1500), 18 species that are now extinct in the wild (but still existing in captivity) and 69 "possibly extinct" species.
The number of prehistoric (fossil) species of gastropods is at least 15,000 species.
Read more about this topic: Gastropoda
Famous quotes containing the word diversity:
“... city areas with flourishing diversity sprout strange and unpredictable uses and peculiar scenes. But this is not a drawback of diversity. This is the point ... of it.”
—Jane Jacobs (b. 1916)
“We call the intention good which is right in itself, but the action is good, not because it contains within it some good, but because it issues from a good intention. The same act may be done by the same man at different times. According to the diversity of his intention, however, this act may be at one time good, at another bad.”
—Peter Abelard (1079–1142)
“The diversity in the faculties of men, from which the rights of property originate, is not less an insuperable obstacle to a uniformity of interests. The protection of these faculties is the first object of government.”
—James Madison (1751–1836)