Taxonomy of Finfish (1+2)

SPHYRNA LEWINI

Sphyrna lewini (Cuvier, Griffith & Smith, 1834)

Classification:

Phylum: Chordata

Class: Chondrichthyes

Subclass : Elasmobranchii

Order Carcharhiniformes:

Family : Sphyrnidae Genera : Sphyrna

Species : lewini

Key character used for the 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 Sphyrnidae :Hammerheads

• Anterior portion of head much flattened dorso-ventrally and widely expanded laterally in "hammer" form, with the eyes at its outer edges.
• Two dorsal fins, the first one is high and pointed.
• Dorsal fins without spine
• Teeth blade-like, with a single cusp.
• Precaudal pits present.

Key character used for the identification of the genus Sphyrna

• Expanded lateral blades of head relatively broad,not winglike, and without small bumps along edges in front of nostrils:
• width across head less than 31% of total length;
• nostrils narrow, less than half the mouth width

Key character used for the identification of the species lewini

• Median indentation present on anterior margin of head;
• free rear tip of second dorsal fin nearly reaching upper caudal fin origin:
• anal fin base noticeably larger than that of second dorsal
• pelvics with a nearly straight posterior margin;