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Order: Assemblage of Related Families (Taxonomic Category)

Biology · The Living World · NEET

An order is a taxonomic category that groups together related families that share a few similar characters. It sits above family and below class in the hierarchy (Species -> Genus -> Family -> Order -> Class). Memory hook: "Order = a family of families." Because it is a higher category, the members share fewer common features than the genera inside one family.
ORDER = Assemblage of Related FamiliesFamily Felidae (cats)Family Canidae (dogs)Family Muscidae (fly)ORDER (e.g. Carnivora)CLASS (higher up)Related families join to form an order (few shared characters)
Related families (Felidae, Canidae) join to form an order such as Carnivora; several orders together form a class. Order sits above family and below class.

Your doubts, answered

What exactly is an 'order' in classification?

An order is a rank in the taxonomic hierarchy that brings together related families. NCERT says: 'Order being a higher category, is the assemblage of families which exhibit a few similar characters.' So you first group species into genera, group related genera into a family, and then group related families into an order.

Is order above or below family? I keep mixing this up.

Order is ABOVE family and BELOW class. The full ascending (low to high) order is: Species -> Genus -> Family -> Order -> Class -> Phylum -> Kingdom. So an order is bigger than a family and contains many families, but many orders together make up one class. Memory trick: 'F' comes before 'O' in the alphabet, and Family comes before Order going upward.

Why do members of an order share fewer characters than members of a family?

As you move UP the hierarchy, the number of shared (common) characters decreases and the group becomes larger. A family shares many characters. An order is higher, so its families share only 'a few similar characters'. This is why NEET often asks which rank has more common features - lower categories always share more.

What are the standard NEET examples of order?

Animals: order Carnivora includes families Felidae (cats) and Canidae (dogs). Order Diptera includes the housefly's family Muscidae. Order Perissodactyla includes the horse's family Equidae. Order Primata includes monkey, gorilla and gibbon. Plants: order Polymoniales includes families Convolvulaceae and Solanaceae, grouped mainly on floral characters.

How do I know Diptera is an order and not a family or class?

Learn the pattern of each rank in a full example. For housefly: Species Musca domestica -> Family Muscidae -> Order Diptera -> Class Insecta -> Phylum Arthropoda. Diptera is the order, Muscidae is the family. In NEET matching questions, the family name is usually the more specific one and the order groups several families.

On what basis are plant families put into the same order?

For plants, orders are often identified using FLORAL characters (features of the flower). NCERT gives the example that Convolvulaceae and Solanaceae are placed in the order Polymoniales mainly based on floral characters.

⚠️ The NEET trap
✗ Perissodactyla is the FAMILY of horse.
✓ Perissodactyla is the ORDER of horse; Equidae is its family.
🧠 Words ending in '-idae' are usually FAMILY names (Equidae, Felidae, Canidae, Muscidae). If it does not end in -idae, do not assume it is the family. Perissodactyla and Carnivora are ORDERS.

Real NEET questions

NEET 2017

Which of the following represents order of 'Horse'?

A · Equidae
B · Perissodactyla ✓
C · Caballus
D · Ferus
Solution: For horse (Equus caballus) the ORDER is Perissodactyla. Equidae is its family, while caballus/ferus are specific epithets, not the order. NCERT (section 1.2.4 Order): 'Order being a higher category, is the assemblage of families which exhibit a few similar characters.'
NEET 2016 Phase 2

Match Column-I with Column-II for housefly classification: A. Family, B. Order, C. Class, D. Phylum with (i) Diptera, (ii) Arthropoda, (iii) Muscidae, (iv) Insecta.

A · A-(iii), B-(i), C-(iv), D-(ii) ✓
B · A-(iii), B-(ii), C-(iv), D-(i)
C · A-(iv), B-(iii), C-(ii), D-(i)
D · A-(iv), B-(ii), C-(i), D-(iii)
Solution: For housefly (Musca domestica): Family Muscidae, Order Diptera, Class Insecta, Phylum Arthropoda. So Family->Muscidae(iii), Order->Diptera(i), Class->Insecta(iv), Phylum->Arthropoda(ii). The ORDER of housefly is Diptera.

Solved The Living World NEET PYQs

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Frequently asked

Is order higher or lower than class?

Order is LOWER than class. Many related orders together form one class. For example, orders Primata and Carnivora both sit inside class Mammalia.

Give one plant order example for NEET.

Order Polymoniales includes the families Convolvulaceae and Solanaceae, grouped mainly on the basis of floral characters.

What is the order of human beings?

Humans (Homo sapiens) belong to order Primata, family Hominidae, class Mammalia. Primata also includes monkey, gorilla and gibbon.

Do all families in one order share many characters?

No. They share only a FEW similar characters, fewer than the genera share within a single family, because order is a higher category.

Related concepts:
Family: A Group of Related GeneraClass: A Group of Related OrdersCorrect Order of Taxonomic CategoriesClassification of Horse (Order Perissodactyla)Classification of Housefly (Diptera)
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Biology MCQs (free, chapter-wise)The Living World PYQs