Segmentation
Discusses metamerism, where the body is externally and internally divided into serial segments.
What is Segmentation?
The division of the body of an animal into a series of similar or identical parts or segments.
Key points
- Define segmentation and metamerism.
- Identify animals that exhibit segmentation.
- Explain the advantages of a segmented body plan.
- Differentiate between true segmentation and superficial segmentation.
Common exam trap
Confusing segmentation with superficial body divisions (like in flatworms).
Definitions
- Term
Segmentation
- Meaning
The division of the body of an animal into a series of similar or identical parts or segments.
- Term
Metamerism
- Meaning
The condition of having a body made up of a series of repeating segments (metameres).
- Term
Metamere
- Meaning
One of the repeating segments that make up the body of a segmented animal.
- Term
Somite
- Meaning
A block of mesodermal tissue formed from the segmentation of the paraxial mesoderm during embryonic development, giving rise to vertebrae, ribs, and skeletal muscles.
Learning objectives
Define segmentation and metamerism.
Identify animals that exhibit segmentation.
Explain the advantages of a segmented body plan.
Differentiate between true segmentation and superficial segmentation.
Prerequisites
Basic understanding of animal phyla and their characteristics.
Knowledge of body plans (e.g., bilateral symmetry).
Understanding of organ systems.
Common mistakes
Confusing segmentation with superficial body divisions (like in flatworms).
Assuming all segmented animals have identical segments.
Overlooking the internal, as well as external, nature of segmentation.
Keywords
Segmentation
Metamerism
Metameres
Annelida
Arthropoda
Chordata
Body plan
Serial repetition
Locomotion
Specialization
Practice preview
In which of the following phyla is true segmentation (metamerism) a characteristic feature?…
easy
Which of the following statements about segmentation is INCORRECT?…
easy
The body of an earthworm is externally divided into numerous segments. Internally, these segments are also separated by partitions. This type of body organization is known as:…
medium