Question:
Pentamerous radial symmetry is a characteristic feature primarily observed in:
Pentamerous radial symmetry is a characteristic feature primarily observed in:
Show Hint
Remember that echinoderms are bilateral as larvae but show pentamerous radial symmetry as adults. This shift from bilateral to radial symmetry is a popular and frequently tested concept in animal kingdom classification.
Updated On: Jun 3, 2026
- Ctenophores
- Larval stages of Echinoderms
- Sea Anemones
- Adult Echinoderms
Show Solution
Verified By Collegedunia
The Correct Option is D
Solution and Explanation
Step 1: Understanding the Question:
This question is based on animal kingdom classification and symmetry. We are asked to identify which group of organisms or developmental stage is characterized by pentamerous radial symmetry, where the body can be divided into five equal sectors around a central axis.
Step 2: Detailed Explanation:
• Pentamerous radial symmetry is a distinct anatomical arrangement where body parts are arranged in groups of five or multiples of five radiating from a central oral-aboral axis. This is a unique and defining hallmark of the phylum Echinodermata.
• Echinoderms undergo a major structural transition during their life cycle. The larval stages of echinoderms (e.g., bipinnaria, pluteus) are bilaterally symmetrical and free-swimming, which is their primitive ancestral state.
• During metamorphosis, the bilateral larva transforms into a radial, benthic (bottom-dwelling) adult. This change is associated with their slow-moving or sessile habit. Therefore, pentamerous radial symmetry is exhibited specifically by adult echinoderms.
• Ctenophores (comb jellies) display biradial symmetry, which is a blend of radial and bilateral characteristics.
• Sea anemones belong to the phylum Cnidaria (class Anthozoa). They possess radial symmetry, but it is typically hexamerous (six-part) or octamerous (eight-part) rather than pentamerous.
Step 3: Final Answer:
Pentamerous radial symmetry is a characteristic feature of adult echinoderms, while their larval stages are bilaterally symmetrical.
This question is based on animal kingdom classification and symmetry. We are asked to identify which group of organisms or developmental stage is characterized by pentamerous radial symmetry, where the body can be divided into five equal sectors around a central axis.
Step 2: Detailed Explanation:
• Pentamerous radial symmetry is a distinct anatomical arrangement where body parts are arranged in groups of five or multiples of five radiating from a central oral-aboral axis. This is a unique and defining hallmark of the phylum Echinodermata.
• Echinoderms undergo a major structural transition during their life cycle. The larval stages of echinoderms (e.g., bipinnaria, pluteus) are bilaterally symmetrical and free-swimming, which is their primitive ancestral state.
• During metamorphosis, the bilateral larva transforms into a radial, benthic (bottom-dwelling) adult. This change is associated with their slow-moving or sessile habit. Therefore, pentamerous radial symmetry is exhibited specifically by adult echinoderms.
• Ctenophores (comb jellies) display biradial symmetry, which is a blend of radial and bilateral characteristics.
• Sea anemones belong to the phylum Cnidaria (class Anthozoa). They possess radial symmetry, but it is typically hexamerous (six-part) or octamerous (eight-part) rather than pentamerous.
Step 3: Final Answer:
Pentamerous radial symmetry is a characteristic feature of adult echinoderms, while their larval stages are bilaterally symmetrical.
Was this answer helpful?
0
0
Top AP EAPCET Zoology Questions
- The incorrect statement for subspecies
- The equation which explains relation of species–area on logarithmic scale
- Life span of blood platelets is
- Assertion (A): The activated osteoblasts start deposition of mineral material to join fractured bone.
Reason (R): The major part of inorganic matter of bone is collagen. - Choose the correct statement among the following
View More Questions
Top AP EAPCET Animal Kingdom Questions
- Assertion (A): Arthropods are schizocoelomates
Reason (R): Coelom in arthropods is formed by splitting of mesoderm - Identify the flatworms among the following non-chordate animals:
I. Euspongia
II. Aurelia
III. Beroe
IV. Taenia
V. Wuchereria
VI. Convoluta Match the following:
Zoological Name Common Name A) Pila I) Apple snail B) Lepisma II) Silver fish C) Daphnia III) Water flea D) Aranea IV) Spider Study the following and pick up the correct combinations:
Sl.No. Classes Features Examples I Osteichthyes Filamentous gills Scoliodon II Amphibia Sternum appeared first time Ichthyophis III Reptiles Temporal fossae Bungarus IV Aves Corpus callosum in brain Corvus - The following are the names of larvae of certain phyla. Identify the larva(e) that belongs to Annelida.
I) Parenchymula
II) Planula
III) Miracidium
IV) Nauplius
V) Glochidium
VI) Trochophore
VII) Bipinnaria
View More Questions
Top AP EAPCET Questions
- A body is projected from the ground at an angle of $\tan^{-1} \left( \frac{8}{7}\right)$ with the horizontal. The ratio of the maximum height attained by it to its range is
- The four quantum numbers of the valence electron of potassium are :
- A lens forms real and virtual images of an object, when the object is at $u_{1}$ and $u_{2}$ distances respectively. If the size of the virtual image is double that of the real image, then the focal length of the lens is (take, the magnification of the real image as $m$ )
- Two spheres $P$ and $Q$, each of mass $200\, g$ are attached to a string of length one metre as shown in the figure. The string and the spheres are then whirled in a horizontal circle about $O$ at a constant angular speed. The ratio of the tension in the string between $P$ and $Q$ to that of between $P$ and $O$ is $(P$ is at mid-point of the line joining $O$ and $Q$ )
- The volume of $0.02\, M$ acidified permanganate solution required for complete reaction of $60\, mL$ of $0.01\, MI^{-}$ ion solution to form $I_2$ in $mL$ is
View More Questions