Significant counts and characters of the Oregon specimen (UW 156810) include the following: vertebrae 45; dorsal-fin rays 49; analfin rays 41; pectoral-fin rays 20, 19; scales in lateral series 48; total gill rakers
8 (1 +1 + 6) plus 4 anterior rounded hump-like rudiments.
The total number of dorsal rays, vertebrae and gill rakers
are also diagnostic.
Instead, I focused on the more clearly defined identification criteria such as number of spines, shape of the fins, and gill rakers
. The key on page 54 will help you correctly identify the common offshore jack species of Florida.
apparatus and food selectivity among mackerels, tunas and dolphin.
Herein we extend our study of the same pleuronectiform taxa by presenting the results of our examination of the gill rakers
, jaw teeth and the teeth of the pharyngeal tooth plates, aspects previously not studied but potentially useful for the investigation of taxonomy, phylogeny and diet.
The number of soft rays of the second dorsal fin, the left pectoral fin and of gill rakers
of the first left gill arch were counted.
The gills are related to many important functions of all fishes; the first and important function is that the gills are considered the main respiratory sites of gas exchange in all fishes (Moyle & Cech, 1996), while the secondary function is related to feeding habits where the organization of gill filaments and rakers were reflected to the feeding habits of the fish (Fernandes et al., 2003; Kumari et al, 2009), in which the organization and size of the gill rakers
played a role in controlling the size of food particles eaten.
We augmented the meristics used by previous authors with counts of dorsal-fin spines, of branched and unbranched pectoral-fin rays on both sides of the fish, of transverse lateral scale rows, and of posterior and anterior gill rakers
from the left side of the fish.
Diagnosis: Dorsal rays XI,9 (1 female paratype with XI1,9); anal rays 111,9; pectoral rays 15; lateral line scales 17+7; median predorsal scales 5; horizontal rows of scales on cheek 2; gill rakers
13-15; body depth 2.85-3.40 in SL; body width 1.95-2.15 in body depth; head length 2.75-2.90 in SL; snout length 4.1-4.4 in head length; pelvic fin short, not reaching the base of the anal fin, 4.15-4.65 in SL; caudal fin rounded to truncate in females and moderately to strongly lunate in males, caudal concavity as great as 0.8 in head; eye large, orbit diameter 3.55-3.90 in head length.
This diet shift can be due to an increase in the gill raker
spacing or short gill rakers
, the changes in the gill raker
morphology of C.
The gill rakers
are cartilaginous or bony structures that project to the inside of the pharyngeal cavity and whose structure changes according to the feeding habit of the fish.