CLASSIFICATION OF SPHENODON : TUATARA
PHYLUM :- CHORDATA (Notochord, dorsal tubular nerve cord present and gill slits present )
Group :- CRANIATA ( Definite head. Cranium with brain present )
Sub-phylum :- VERTEBRATA ( vertebral column present)
Division :- GNATHOSTOMATA ( Jaws and paired appendages present )
Super class :- TETRAPODA ( Paired limbs, lungs, bony skeleton and cornified skin)
Class :- REPTILIA ( Scaly vertebrates with right and left aortic arches. Single condyle, pulmonary respiration. Embryo with amnion and allantois ).
Sub-class :- DIAPSIDA ( Skull with two temporal openings separated by postorbital and squamosal ).
Order :- RHYNCHOCEPHALIA ( Living fossil, lizard-like, Ribs single headed and with uncinate processes. Vertebrae amphicentrous ).
Genus :- Sphenodon
Species :- punctatum
Sphenodon is found in New Zealand and specially in the islets of Bay of Plenty.
HABIT AND HABITAT
Sphenodon lives in burrows, leads semiaquatic life. It is nocturnal and eats insects, molluscs or small invertebrates. It also produces frog-like croak. Breeding season November to February.
GENERAL CHARACTERSTICS OF SPHENODON : TUATARA
- Commonly called as tuatara.
- Animal is lizard-like having dull olive-green colour with white and yellow spots and measuring about 75 cm. Body divided into head, neck, trunk and tail. Head contains eye, nostril and mouth.
- It contains scaly skin and long tail.
- Forelimbs and hind limbs adapted for walking having clawed digits.
- Several backwardly directed hook or crest like spines extend all along mid-dorsal line.
- Skull contains two complete fossae, quadrate is fixed, postfrontals are separate (only in Sphenodon) and upper jaw has beaks. Teeth acrodont. Mandibles joined by ligament. Between skull and atlas is
proatlas. Sternum present and vertebrae amphicoelous. Caudal vertebrae have chevron bones.
- Eye is photosensitive.
- Anal opening transverse. Male without copulatory organ. About 10 eggs with hard white shell are laid in holes in the ground. Eggs require 13 months to hatch.
Sphenodon punctatum is an important living fossil. It has survived from pennian and is fast approaching towards extinction. It is protected by law. The tuatara contains several primitive features, such as two temporal fossae, amphicentrous vertebrae, pineal eye, uncinate processes in the rib, vomerine teeth in young, horny beak on upper jaw and absence of copulatory apparatus in males. Tuatara is close to the type from where all diapsid reptiles might have originated.
This reptile has rows of spines on the back and above features, hence it is Sphenodon.
- Book of Practical Zoology VERTEBRATE by S.S.LAL – Rastogi Publications.
- SOURCES OF IMAGES – https://www.google.com/url?sa=i&url=https%3A%2F%2Fanimals.sandiegozoo.org%2Fanimals%2Ftuatara&psig=AOvVaw1dHdPNnPTuuoHe1KAQuhmv&ust=1604395968438000&source=images&cd=vfe&ved=2ahUKEwjehb_vxuPsAhUqkUsFHR0gAx8Qr4kDegUIARC6AQ