91影视

Snails are molluscans and possess both planktonic and non-planktonic larvae. These larvae show a broad distribution and are studied by many researchers to examine the mode of dispersal. The larvae of snails are isolated from each other. Fossil records are reviewed to explore more about the distribution of larvae.

The number of planktonic larvae was 13, and the number of non-planktonic larvae was 29. For calculating the persistence time of species, the length of the bar is multiplied with the conversion factor of 3.6 my/cm. The formula which represents the calculation is

\({\bf{Persistent}}{\rm{ }}{\bf{time}}{\rm{ }}{\bf{of}}{\rm{ }}{\bf{the}}{\rm{ }}{\bf{species}} = {\bf{length}}{\rm{ }}{\bf{of}}{\rm{ }}{\bf{the}}{\rm{ }}{\bf{bar}}{\rm{ }} \times {\rm{ }}{\bf{conversion}}{\rm{ }}{\bf{factor}}{\rm{ }}\left( {{\bf{3}}.{\bf{6}}{\rm{ }}{\bf{my}}/{\bf{cm}}} \right)\)

The persistent time obtained by measuring the length of the bar and multiplying it with the conversion factor indicates the position of species in the graph that is left to the right. In other words,it suggests the resistance time of the species moving from left to right in the graph.

Therefore, the average bar length of the planktonic larva is 1.29 cm/bar, and the average length of non-planktonic species is 0.47 cm/bar.