Assertion: spiny dogfish's fin | /r/HasProperty | first dorsal
Facets:
Source sentences:
text: The spiny dogfish (Squalus acanthias) and the roughskin dogfish (Cirrhigaleus asper) have a first dorsal fin originating over or posterior to the free rear tips of the pectoral fins.
text: Spiny dogfish are actively moving the first dorsal fin independently of the trunk, which is corroborated by muscle activity that differs from the adjacent epaxial muscle.