Question

What are cycloid and ctenoid scales?

Answer 1

Cycloid scales

1. Fish scales are classified as cycloid or ctenoid scales.
2. Cycloid scales are smooth-edged scales found mostly in lower-order teleost fishes such as carp and salmon.
3. Cycloid scales appear to be the inner layer of ganoid or cosmoid scales.
4. Cycloid scales are thin, round, or oval in form, with growth rings visible.
5. They are overlapping which allows for greater flexibility in movement.

Ctenoid Scales

1. Ctenoid Scales are firmly attached with numerous little comb-like teeth or spines on their exposed free hind portions that are not overlapped.
2. Ctenoid Scales provide predator defence.
3. These scales are found in modern higher teleosteans.
4. Ctenoid scales are identical to cycloid scales, with the exception that they include spines along their free edges.
5. Bass and crappie both have ctenoid scales.