Question

How does a bony fish differ from a shark in terms of its external morphology? How do the fins differ between these two groups of fishes (generalize)?

A) Bony fishes have scales and operculum; sharks have placoid scales and no operculum.
B) Bony fishes have paired pectoral and pelvic fins; sharks have unpaired pectoral and pelvic fins.
C) Bony fishes have a swim bladder for buoyancy; sharks rely on their liver for buoyancy.
D) Bony fishes have a terminal mouth; sharks have a ventral mouth on the underside.

Answer 1

Bony fishes have overlapping scales and an operculum, paired fins supported by rays or lobes, and a swim bladder for buoyancy; sharks have placoid scales, no operculum, fins supported by cartilage, and a liver for buoyancy, along with a ventral mouth.

Step-by-step explanation:

The primary differences in external morphology between bony fish and sharks include the type of scales, the presence of an operculum, and fin structures. Bony fishes typically have overlapping scales and a protective operculum that covers their gills, while sharks have tooth-like placoid scales and no operculum. When comparing fins, both bony fishes and sharks have paired pectoral and pelvic fins, but their structure and composition differ significantly. Bony fishes have fin rays or lobe-like structures supporting their fins, whereas sharks have fins supported by cartilage.

The main distinguishing feature between bony fishes and sharks in regards to buoyancy is the swim bladder in bony fishes and the reliance on a large oil-filled liver in sharks. Additionally, the morphology of their mouths differs, bony fishes often having a terminal mouth whereas sharks generally have a ventral mouth on the underside of their head.