Question

During a field trip a student observed a marine organism with worm-like body. The cylindrical body was divisible into proboscis, collar and a long trunk. The organism may be ____ .

• A. Pterophyllum
• B. Trygon
• C. Balanoglossus
• D. Ophiura

Hint:

Balanoglossus, an acorn worm, is identified by its three-part body: proboscis, collar, and trunk.

Answer 1

The Correct Option is C

• Observation Analysis: The organism has a worm-like, cylindrical body divisible into three distinct regions: proboscis, collar, and a long trunk. This description is characteristic of certain marine organisms with specific anatomical features.
• Organism Identification:
  • Balanoglossus: A marine acorn worm (Hemichordata) with a body divided into proboscis (used for feeding), collar (bearing gills), and a long trunk (for digestion and respiration). This matches the description perfectly.
  • Pterophyllum: A type of freshwater angelfish, which has a flattened, disc-like body, not worm-like or segmented into proboscis, collar, and trunk. Incorrect.
  • Trygon: A genus of stingrays with a flattened, disc-shaped body and a long tail, not matching the cylindrical, segmented description. Incorrect.
  • Ophiura: A brittle star with a central disc and long, flexible arms, lacking the proboscis, collar, and trunk structure. Incorrect.
• Biological Context: Balanoglossus is a hemichordate, often studied for its evolutionary link to chordates, and its body plan aligns with the student's observation of a marine, worm-like organism with the specified divisions.
• Option Analysis:
  • (1) Pterophyllum: Does not fit the description. Incorrect.
  • (2) Trygon: Does not match the body segmentation. Incorrect.
  • (3) Balanoglossus: Matches the anatomical features described. Correct.
  • (4) Ophiura: Lacks the proboscis, collar, and trunk structure. Incorrect.
• Conclusion: The organism is most likely Balanoglossus, as its body structure (proboscis, collar, and trunk) corresponds to the student's observation.