Taxonomy of Finfish (1+2)

Rhizoprionodon acutus (Ruppell,1837)

Classification

Phylum: Chordata

Class: Chondrichthyes

Subclass : Elasmobranchii

Order Carcharhiniformes:

Family : Carcharhinidae

Genera :Rhizoprionodon Species : acutus

Key character used forthe identification of the order Carcharhiniformes:

• Two dorsal fins without spines
• anal fin present
• Five gill slits. the last one to three over the pectoral fin
• Gill rakers absent
• Eye with nictitating fold or membrane
• Intestinal value of spiral or scroll type

Key character used for the identification of the family Carcharhinidae:

• Eyes on sides of head, with a well-developed nictitating lower eyelid;
• Intestine with a scroll valve
• Anterior teeth in upper jaw smaller than lateral teeth and not separated from them by smaller intermediate teeth on each side
• upper edge of caudal fin with a rippled or undulating margin;
• precaudal pits present;

Key character used forthe identification of the genus Rhizoprionodon

• Head moderately depressed to conical; pectoral fins narrower; their length 4/5 or less of anterior margins; free rear tip of first dorsal reaching at most to pelvic fin origins to (usually well anterior to them); posterior margin of caudal fin deeply incised
• Second dorsal fin origin well behind anal fin origin, usually over or slightly anterior to anal fin insertion; preanal ridges extremely long
• No eye notches; first dorsal fin base usually less than 2 times in distance between pectoral to pelvic fin bases

Key character used for the identification of the species Rhizoprionodonacutus

• first dorsal fin base usually 2 times in distance between pectoral to pelvic fin bases,
• labial furrows well-developed and moderately long,the upper ones about equal in length to eye diameter
• and ending well behind eyes;
• teeth similar in both jaws, low-crowned, oblique and narrow-cusped,
• precaudal vertebrae more 55 to 79