Question

The protochordate from which chordates may have evolved is

• A. Herdmania
• B. Balanoglossus
• C. Branchiostoma
• D. None of the above

Answer 1

The correct option is B Balanoglossus

Balanoglossus is an ocean-dwelling acorn worm genus of great zoological interest because, being a hemichordate (protochordate), it is an "evolutionary link" between invertebrates and vertebrates. Balanoglossus is a deuterostome, and resembles the Ascidians or sea squirts, in that it possesses branchial openings, or "gill slits". It has a notochord in the upper part of the body and has no nerve chord. It does have a stomochord, however, which is gut chord within the collar.

Balanoglossus is a protochordate supplied with gill slits and a dorsal tubular nervous system and requires only the notochord and segmental myotomes.

So, the correct answer is option B.