Which chordate characteristics are present in a sea squirt (tunicate) during its larval stage?

• A. Scales and paired fins
• B. Vertebral column and jaws
• C. Lungs and amniotic egg
• D. Notochord, dorsal hollow nerve cord, and post-anal tail

Answer: (D)

Verified step by step guidance

1. Understand the question: The problem asks which chordate characteristics are present in a sea squirt (tunicate) during its larval stage. Chordates are a group of animals that share specific features during some stage of their life cycle.
2. Recall the defining characteristics of chordates: Chordates typically possess a notochord, a dorsal hollow nerve cord, pharyngeal slits, a post-anal tail, and an endostyle or thyroid gland during some stage of development.
3. Focus on the larval stage of tunicates: Tunicates, also known as sea squirts, are chordates that exhibit these characteristics primarily during their larval stage. As adults, they lose some of these features, such as the notochord and post-anal tail, as they transition to a sessile lifestyle.
4. Identify the chordate features present in the larval stage: During the larval stage, tunicates possess a notochord (a flexible rod-like structure that provides support), a dorsal hollow nerve cord (a tube-like structure that runs along the back and is part of the nervous system), and a post-anal tail (a tail that extends beyond the anus). These features are key identifiers of chordates.
5. Exclude irrelevant options: The other options provided in the question, such as scales, paired fins, vertebral column, jaws, lungs, and amniotic egg, are not characteristics of tunicates during their larval stage. These features are associated with other groups of animals, such as vertebrates or amniotes.