Which statement about lancelets and tunicates is true?

Which statement about lancelets and tunicates is true?

• A. Both are vertebrates
• B. Lancelets are chordates, tunicates are not
• C. Lancelets have a heart while tunicates do not
• D. Both are invertebrate chordates

Answer: (D)

The main idea is that vertebrates are defined by having a backbone. Lancelets and tunicates are both chordates, sharing features like a notochord, dorsal nerve cord, and pharyngeal slits, but they lack a vertebral column. That combination places them invertebrate chordates. Lancelets (cephalochordates) keep a notochord and dorsal nerve cord throughout life and have a simple, small body plan adapted to their filter-feeding lifestyle, without a true backbone. Tunicates (urochordates) appear as sacs in adulthood and lose the notochord and dorsal nerve cord, though these features are present in the larval stage. This means both groups are chordates, but neither has a backbone, so they are not vertebrates. So the true statement is that both are invertebrate chordates. The other options misstate their vertebrate status, their chordate identity, or emphasize a heart feature that isn’t the defining criterion for this classification.

The main idea is that vertebrates are defined by having a backbone. Lancelets and tunicates are both chordates, sharing features like a notochord, dorsal nerve cord, and pharyngeal slits, but they lack a vertebral column. That combination places them invertebrate chordates.

Lancelets (cephalochordates) keep a notochord and dorsal nerve cord throughout life and have a simple, small body plan adapted to their filter-feeding lifestyle, without a true backbone. Tunicates (urochordates) appear as sacs in adulthood and lose the notochord and dorsal nerve cord, though these features are present in the larval stage. This means both groups are chordates, but neither has a backbone, so they are not vertebrates.

So the true statement is that both are invertebrate chordates. The other options misstate their vertebrate status, their chordate identity, or emphasize a heart feature that isn’t the defining criterion for this classification.