Which characteristics define a chordate?
1)The presence of a well-developed circulatory system
2)The development of an anus from the blastopore
3)The ability to live on land
4)The presence of four specific morphological traits
The Correct Answer and Explanation is :
The correct answer is:
4) The presence of four specific morphological traits.
Chordates are a group of animals defined by the presence of four key morphological traits at some point during their development, although not all of these traits are necessarily present in the adult form. These four traits are:
- Notochord: A flexible, rod-shaped structure that provides support to the body. It is usually located along the back and serves as a primary skeletal structure in the early stages of development, although it is often replaced by the vertebral column (spine) in vertebrates.
- Dorsal Hollow Nerve Cord: This is a nerve cord that runs along the back of the organism. It is typically the precursor to the central nervous system, which includes the brain and spinal cord in vertebrates.
- Pharyngeal Slits (or Pouches): These are openings found in the pharyngeal region (throat area) that allow water to pass through for feeding or respiration. In aquatic chordates like fish, they develop into gills. In terrestrial chordates, these structures may be present during embryonic development but are modified or disappear as the organism matures.
- Post-Anal Tail: A tail that extends beyond the anus. It is an important feature for locomotion in many chordates, particularly those that swim, but it may be reduced or absent in adult forms of some groups (e.g., humans).
These traits are found in all chordates at some stage of their development, making them the defining characteristics of the group. The other options listed (a well-developed circulatory system, the development of an anus from the blastopore, and the ability to live on land) are not exclusive to chordates. While many chordates do have these features, they are not universal defining traits of the group.
Let me generate an image illustrating the four key characteristics of a chordate.
Here is an illustration showing the four defining characteristics of chordates: the notochord, dorsal hollow nerve cord, pharyngeal slits, and post-anal tail. These features are essential for identifying organisms in the chordate group.
