tuatara


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tuatara

(to͞o'ətär`ə) or

tuatera

(–tā`rə), lizardlike reptilereptile,
name for the dry-skinned, usually scaly, cold-blooded vertebrates (see Chordata) of the order Reptilia. Reptiles are found in a variety of habitats throughout the warm and temperate regions (except on some islands), with the greatest variety in the tropics.
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, Sphenodon punctatus, last survivor of the reptilian order Rhynchocephalia, which flourished in the early Mesozoic era before the rise of the dinosaurs. Also called sphenodon, it is found on islands off the New Zealand coast and in Karori Wildlife Sanctuary, Wellington, New Zealand. The olive colored, yellow-speckled tuatara reaches a length of 2 ft (60 cm) or more. It is very lizardlike in external form, with a crest of spines down its neck and back. However, its internal anatomy, its scales, and the attachment of its teeth are quite different from those of lizards, and its body chemistry allows it to function at temperatures close to freezing. Like certain lizards, it possesses a vestigial third eye (pineal eye) on top of its head, but this organ is probably not sensitive to light. Tuataras usually inhabit the breeding burrows of certain small petrels. They feed on small animals, especially insects, and reproduce by laying eggs. Captive tuataras mature in about 20 years, and it appears that their life span may exceed a century by several decades.

Tuataras lived on the mainland of New Zealand before the arrival of the Maoris but either were exterminated by hunting or died out as a result of the altered environment. Their survival on the offshore islands was threatened by the introduction of sheep, which altered the vegetation by grazing; however, they are now under strict government protection, and their numbers are increasing. In 2005 tuataras were reintroduced on the mainland at the Karori Wildlife Sanctuary.

Tuataras are classified in the phylum ChordataChordata
, phylum of animals having a notochord, or dorsal stiffening rod, as the chief internal skeletal support at some stage of their development. Most chordates are vertebrates (animals with backbones), but the phylum also includes some small marine invertebrate animals.
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, subphylum Vertebrata, class Reptilia, order Rhynchocephalia.

Tuatara

 

(Sphenodon punctatum), the sole surviving representative of the subclass Rhynchocephalia, known from the Triassic. Tuataras have biconcave vertebrae, two pairs of temporal fossae and two corresponding cranial arches, a quadrate bone immovably attached to the skull, a well-developed pineal body, and, as in fish, a sinus venosus in the heart. Externally, a tuatara resembles a lizard, with its massive body, large head, and penta-dactyl legs. On the back and tail is a low ridge of triangular scales. The body coloring is a dull olive-green.

Tuataras occupied both main islands of New Zealand prior to the arrival of the Europeans, but they were subsequently exterminated. They have survived only on rocky islets in the Bay of Plenty, where a special sanctuary was created for them. Tuataras live in holes approximately 1 m in depth, in which small petrels also frequently nest. They are active at twilight and at night. They feed on insects and other invertebrates and occasionally the eggs and nestlings of petrels. Mating takes place in January. From October to December, females lay eight to 15 hard-shelled eggs in the holes. Embryonic development lasts 12–15 months. Sexual maturity is not reached until age 20. Some tuataras have been known to survive as long as 50 years in captivity.

I. S. DAREVSKII

tuatara

a greenish-grey lizard-like rhynchocephalian reptile, Sphenodon punctatus, occurring only on certain small islands near New Zealand: it is the sole surviving member of a group common in Mesozoic times
References in periodicals archive ?
Isolde said she wept when she discovered the tuatara had hatched.
The new finding may resolve a longstanding debate: whether the tuatara lost an ancestral reproductive organ or its cousins independently gained a pair.
The book concludes with two chapters that take a unique look at tuatara reproductive biology.
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There are many similar stories of island refugia becoming almost the sole home for particular fauna: black robin on Chatham Islands; North Island saddleback on Hen Islands; stitchbird and kokako birds on Little Barrier Island; kakapo birds on Codfish Island; giant weta insects on Poor Knights Islands; tuatara lizards on Stephens Island; and little spotted kiwibirds on Kapiti Island.
After 40 years in captivity, Henry, a tuatara lizard, is now the proud papa of 11 offspring.
Henry the centenarian tuatara had previously shown little interest in mating until an operation to remove a cancerous tumor from his ''nether regions'' restored his libido.
Henry the Tuatara and his mate Mildred, aged between 70 and 80, produced 12 eggs in mid-July.
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Why are all extant sighted vertebrates (with the exception of the tuatara, a rare, primitive reptile from a few remote islands in New Zealand with an additional, "pineal" eye) equipped with two eyes, why not one, why not three or more?