Question

coelacanths and blue whales have more similarities in their bdnf gene sequences than coelacanths and asian bonytongue fish have. this piece of evidence supports the following claim:

coelacanths share a more recent common ancestor with blue whales than with asian bonytongue fish.

which additional piece of evidence best supports the same claim?

coelacanths have a tube - shaped heart with one atrium and one ventricle. blue whales have a four - chambered heart with two atria and two ventricles. asian bonytongue fish have an s - shaped heart with one atrium and one ventricle.

coelacanths have at least six major muscle groups in their pectoral fins that control fin movement for swimming. blue whales have three major muscle groups in their pectoral flippers that stabilize the flippers for steering. asian bonytongue fish do not have muscles in their pectoral fins.

the skeleton of coelacanths is primarily composed of cartilage, with some bones. the skeleton of blue whales is primarily composed of bone, with some cartilage. the skeleton of asian bonytongue fish is primarily composed of bone, with little cartilage.

Explanation:

To support the claim that coelacanths share a more recent common ancestor with blue whales than with Asian bonytongue fish, we need evidence of more shared derived traits (synapomorphies) between coelacanths and blue whales.

• For the first option: Coelacanths and Asian bonytongue fish both have a heart with one atrium and one ventricle, while blue whales have a four - chambered heart. This shows a similarity between coelacanths and Asian bonytongue fish, not supporting the claim.
• For the second option: Coelacanths have at least six major muscle groups in pectoral fins, blue whales have three, and Asian bonytongue fish have none. The muscle - group pattern in coelacanths and blue whales is more similar (both have muscle groups in pectoral appendages for movement - related functions) compared to Asian bonytongue fish (no muscles in pectoral fins). This indicates a closer evolutionary relationship between coelacanths and blue whales.
• For the third option: Coelacanths' skeleton is primarily cartilage with some bone, blue whales' is primarily bone with some cartilage, and Asian bonytongue fish's is primarily bone with little cartilage. The skeletal composition of coelacanths is less similar to blue whales than to Asian bonytongue fish in terms of primary tissue, so this does not support the claim.

Answer:

Coelacanths have at least six major muscle groups in their pectoral fins that control fin movement for swimming. Blue whales have three major muscle groups in their pectoral flippers that stabilize the flippers for steering. Asian bonytongue fish do not have muscles in their pectoral fins.