Chordata and Its Subphyla
Notochord, dorsal nerve cord and pharyngeal slits; urochordates, cephalochordates and vertebrates. (Biology › Animal Kingdom, NEET UG syllabus.)
What is Chordata and Its Subphyla?
A flexible, rod-like structure forming the main support of the body in the embryonic and sometimes adult stages of chordates.
Key points
- Identify and describe the four fundamental characteristics of Chordata.
- Differentiate between the three subphyla of Chordata: Urochordata, Cephalochordata, and Vertebrata.
- Provide examples for each subphylum and explain their distinguishing features.
- Understand the evolutionary significance of the notochord and its fate in different chordate groups.
Common exam trap
Confusing notochord with vertebral column; the vertebral column replaces the notochord in most adult vertebrates.
Definitions
- Term
Notochord
- Meaning
A flexible, rod-like structure forming the main support of the body in the embryonic and sometimes adult stages of chordates.
- Term
Dorsal Hollow Nerve Cord
- Meaning
A tube of nervous tissue that runs along the back (dorsal) of a chordate, which develops into the brain and spinal cord.
- Term
Pharyngeal Gill Slits
- Meaning
Paired openings in the pharynx region of chordates, used for filter feeding or gas exchange.
- Term
Post-anal Tail
- Meaning
An extension of the body that runs posterior to the anus, containing skeletal elements and muscles, present in chordates at some stage.
- Term
Urochordata
- Meaning
A subphylum of Chordata where the notochord is present only in the larval tail and disappears in the adult stage; also known as Tunicata.
- Term
Cephalochordata
- Meaning
A subphylum of Chordata where the notochord extends from the head to the tail region and persists throughout the animal's life.
- Term
Vertebrata
- Meaning
A subphylum of Chordata where the notochord is replaced by a vertebral column (backbone) in the adult stage; also known as Craniata.
- Term
Retrogressive Metamorphosis
- Meaning
A type of metamorphosis where the adult form is simpler or less developed than the larval form, as seen in Urochordates.
Learning objectives
Identify and describe the four fundamental characteristics of Chordata.
Differentiate between the three subphyla of Chordata: Urochordata, Cephalochordata, and Vertebrata.
Provide examples for each subphylum and explain their distinguishing features.
Understand the evolutionary significance of the notochord and its fate in different chordate groups.
Explain the concept of retrogressive metamorphosis in Urochordates.
Prerequisites
Basic understanding of animal classification (phyla, classes).
Knowledge of fundamental animal body plans (symmetry, germ layers, coelom).
Familiarity with terms like triploblastic, coelomate, bilateral symmetry.
Common mistakes
Confusing notochord with vertebral column; the vertebral column replaces the notochord in most adult vertebrates.
Assuming all four chordate characteristics are present throughout the entire life of every chordate (they are present at some stage).
Misidentifying examples of subphyla (e.g., placing Amphioxus in Urochordata).
Forgetting that Urochordates undergo retrogressive metamorphosis, becoming simpler as adults.
Keywords
Chordata
Notochord
Dorsal Hollow Nerve Cord
Pharyngeal Gill Slits
Post-anal Tail
Urochordata
Cephalochordata
Vertebrata
Tunicata
Amphioxus
Lancelet
Ascidia
Retrogressive Metamorphosis
Animal Kingdom
NEET Biology
Practice preview
Which of the following statements about the subphylum Urochordata is INCORRECT?…
hard
All chordates possess the following fundamental features at some stage of their life cycle, EXCEPT:…
medium
Which of the following is a fundamental characteristic present in all chordates at some stage of their life cycle?…
easy