Lesson 6 of 8 · 7 min
Family, order and class
NCERT §1.2.3–1.2.5
Meera's dog barks at the neighbour's cat. Both eat meat, both have fur and four legs. Are they in the same family? And how does a gorilla at the zoo end up in the same class as the lion?
The lesson in notes
In short
A family is a group of related genera that share fewer similarities than the members of a genus or a species do.
In plants, families are recognised using both vegetative and reproductive characters. Solanum, Petunia and Datura, for instance, are three genera grouped in the family Solanaceae.
Among animals, the genus Panthera (lion, tiger, leopard) and the genus Felis (cats) together form the family Felidae. Cats and dogs share some features but differ in others, so they go into two families, Felidae and Canidae.
Species, genus and family rest on a number of similar characters; order and the categories above it are identified on aggregates of characters.
An order is an assemblage of families that show only a few similar characters, fewer than the genera within a family share.
The plant families Convolvulaceae and Solanaceae are placed in the order Polymoniales, mainly on floral characters. The animal order Carnivora includes the families Felidae and Canidae.
A class is a group of related orders. Order Primata (monkey, gorilla, gibbon) and order Carnivora (tiger, cat, dog) are both in class Mammalia, which has other orders as well.