Taxonomy of Finfish (1+2)

Isurus oxyrinchus Rafinesque,1810

Classification

Phylum: Chordata

Class: Chondrichthyes

Subclass : Elasmobranchii

Order Lamniformes

Family : Lamnidae:

Genera : Isurus

Species : I. oxyrinchus

Key character for order Lamniformes:

• Tow dorsal fins, without spines
• anal fin present
• five gill slits, and last two above pectoral fin
• Small spiracle present behing eyes.
• Mouth extending well beyond eyes

Key character used for the identification of the family Lamnidae- Mackerel shark

• Gill opening large
• Teeth few and enlarged
• Gill rakers absent
• Caudal fin nearly symmetrical and caudal peduncle with strong lateral keel and precaudal pit

Key character used for the identification of the genera Isurus

• Upper teeth with smooth edged cusps
• Origin of first dorsal fin posterior to inner corner of pectoral fins when latter are laid back;
• Anal fin origin below about middle of second dorsal fin base

Key character used for the identification of the species Isurus oxyrinchus

• Snout usually acutely pointed
• Cusps of upper and lower anterior teeth recurved at bases but with tips reversed and curving outward;
• Pectoral fins considerably shorter than head,
• Origin of anal fin about under mid-base of second dorsal fin
• Underside of snout and mouth white