SPHYRNA : HAMMER-HEADED SHARK

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1) SPHYRNA : HAMMER-HEADED SHARK

1.1) CLASSIFICATION of SPHYRNA

1.2) Geographical distribution

1.3) Habit and habitat

1.4) GENERAL CHARACTERSTICS OF SPHYRNA : HAMMER-HEADED SHARK

1.5) Special features

1.6) Identification

CLASSIFICATION of SPHYRNA

Phylum :- CHORDATA ( Notochord and dorsal tubular nerve cord present and gill-slits present)

Group :- CRANIATA ( Cranium with brain present ).

Subphylum :- VERTEBRATA (Vertebral column present ).

Division :- Gnathostomata ( Jaws and paired appendages present ).

Super class :- PISCES (Paired fins , gills and skin with scales)

Class :- CHONDRICHTHYES { =ELASMOBRANCHI } (Endoskeleton cartilaginous. Scales usually placoid. spiral valve in intestine ).

Sub-class :- Selachi (Sharks and rays. Gills in seperate clefts. Cloaca present).

Order :- PLEUROTREMATA { =SQUALI } (Pleuro-sides , trema-opening. gill slits lateral, pectoral fins small.)

Family :- SCYLLIDAE ( Asterospondylus. First dorsal fin without spine)

Genus :- SPHYRNA

Geographical distribution

Sphyrna is found in all tropical and sub-tropical sea waters and Pacific ocean, primarily in warm coastal waters.

Habit and habitat

Sphyrna is a common marine fish, adapted for deep sea waters. It is a voracious feeder, active swimmer. It eats small fishes, but because of its attacks on man, it is dreaded as man eater.

GENERAL CHARACTERSTICS OF SPHYRNA : HAMMER-HEADED SHARK

Commonly called as hammer-headed shark due to the hammer-shaped head, which is produced into two prominent lateral lobes supported by corresponding cartilaginous outgrowths from post orbital or lateral ethmoidal regions of skull. Eyes containing nictitating membrane are placed a the distal extremities of the lateral lobes.
Elongated body measuring 4 to 5 metres is divided into head, trunk and tail. The tail is raised upwards and contains caudal fin with fin rays.
Dorsal side is greyish while ventral side is yellowish.
First dorsal fin is situated opposite to pelvic fin and second dorsal fin opposite to anal fin. Both fins are devoid of spines. Pectoral fin near gill openings.
Mouth crescentic and ventral.
5 pairs of gill-slits and lateral in position. Spiracles are absent. Lateral line distinct.
Viviparous, producing about 40 young ones.

Special features

Hammer-headed sharks are closely related to carcharhininae but differ in many cranial characters associated with sphyrnidae cephalic ‘hydrofoil or hammer.