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Tuatara Glossary

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Abdomen – the portion of the body between the thorax and pelvis, containing the stomach, intestines, liver, and other organs; the belly.

Adipose – fatty tissue.

Agamid – any of numerous Old World lizards of the family Agamidae, related to the iguanids.

Allantois – a vascular sac that develops as a sac or diverticulum from the ventral wall of the hindgut in the embryos of mammals, birds, and reptiles and is important in the formation of the umbilical cord and placenta in mammals.

Amnion – a thin, tough, membranous sac that encloses the embryo or foetus of a mammal, bird, or reptile. It is the innermost membrane and is filled with a fluid in which the embryo is suspended.

Amniote – The amniotes are the tetrapod vertebrates that include the Synapsida (mammals and mammal-like reptiles) and Sauropsida (reptiles and dinosaurs, including birds). They are defined by embryonic development that includes the formation of several extensive membranes - the amnion, chorion, and allantois.

Amphicoelous vertebrae – vertebrae with two concave surfaces.

Anatomy – the structure of an animal or plant, or of any of its parts.

Anterior – at or near the head end/front plane of the body.

Antibody – any of a large variety of proteins normally present in the body or produced in response to an antigen which it neutralises, thus producing an immune response. 

Antigen – a substance that when introduced into the body stimulates the production of an antibody. Antigens include toxins, bacteria, foreign blood cells, and the cells of transplanted organs.

Arches – an organ or structure having a curved or bowlike appearance.

Archosauria – a large subclass of diapsid reptiles including: crocodiles, alligators, and many dinosaurs.  

Autotomy - the spontaneous casting off of a limb or other body part, such as the tail of certain reptiles, especially when the organism is injured or under attack.

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Carnivore – an organism that primarily eats flesh.

Caruncle – a fleshy growth. Sometimes referred to as an egg tooth, although that is not strictly correct.

Chorion – the outer membrane enclosing the embryo or foetus of a reptile, bird, or mammal. In placental mammals it contributes to the development of the placenta.

Choroid – the dark-brown vascular coat of the eye between the sclera and the retina.

Cloaca – the common cavity into which the intestinal, urinary, and reproductive canals open in birds, reptiles, amphibians, many fishes, and some mammals

Concave – having a surface that is curved or rounded inwards.

Cone cells – one of the cone-shaped cells in the retina of the eye, sensitive to colour and intensity of light.

Convex – having a surface that is curved or rounded outwards.

Copulation – sexual intercourse.

Cornea – the transparent convex anterior portion of the outer fibrous coat of the eyeball that covers the iris and the pupil and is continuous with the sclera.

Cytoplasm – the jellylike material that makes up much of a cell inside the cell membrane.

Desiccate – to dry up or cause to dry up by depriving or exhausting moisture.

Diapsid – having two openings in the skull behind each eye, characteristic of the subclasses Lepidosauria and Archosauria, which includes all living reptiles except turtles.

Diencephalon – posterior section of the forebrain.

Diurnal – active by day.

Diverticulum – a blind, tubular sac or process branching off from a canal or cavity.

Dorsal – situated on or toward the upper side of the body, equivalent to the back.

Duplex retina – a retina consisting of both, rod cells and cone cells.

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Ectoparasite – parasites found on the surface of the body.

Ectotherms – an organism that regulates its body temperature largely by exchanging heat with its surroundings.

Endemic – belonging exclusively or confined to a particular place or region.

Endoparasite – parasites found within the body.

Endotherm – an organism that generates heat to maintain its body temperature, typically above the temperature of its surroundings.

Erythrocyte – a mature blood cell that contains haemoglobin to carry oxygen to the body’s tissues; a biconcave disc that has no nucleus; red blood cell.  

Extant – in existence; not destroyed or lost.

Extinct – no longer in existence.

Gastralia – abdominal ribs.

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Haemoparasites – parasites found in the blood.

Helminth – a parasitic worm.

Heterophil – an antibody that has an affinity for an antigen other than its specific antigen.

Incubation – to maintain (eggs, organisms, or living tissue) at optimal environmental conditions for growth and development.

Indeterminant growth – when an animal continues to grow throughout its life where resources allow.

Inseminate – to introduce or inject semen into the reproductive tract of (a female).

Intromittent organ – an appendage used during sexual intercourse, such as a penis in mammals.

Iris– the coloured portion of the eye containing a circular opening (the pupil) in its centre, and regulates the amount of light entering the eye.

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Lens – a transparent organ that is convex on both sides, situated behind the iris in the eye and that focuses light waves on the retina.  

Lepidosauria diapsid reptiles, including lizards, snakes and tuatara. 

Leukocyte – blood cells that engulf and digest bacteria and fungi and are an important part of the body's immune defence; white blood cell.

Longevity – the length or duration of life.

Lymphocyte – type of white blood cell (leukocyte) having a large, round nucleus surrounded by a thin layer of nongranular cytoplasm.

Median – of, relating to, or situated in or near the plane that divides an animal into right and left halves.

Metabolism – the chemical processes occurring within a living cell or organism that are necessary for the maintenance of life. In metabolism some substances are broken down to yield energy for vital processes while other substances, necessary for life, are synthesized.

Morphology – the form and structure of an organism.

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Nictitating membrane - a thin membrane, or inner or third eyelid, present in many animals, capable of being drawn across the eyeball, as for protection.

Nocturnal – active at night.

Nucleus – a part of the cell containing DNA and RNA and responsible for growth and reproduction.

Optic nerve – the nerve that carries electrical signals from the retina in the eye to the brain.

Order – order is the name for groups that living organisms are assigned. The four orders of reptiles include Sphenodontia (tuatara), Crocodilia (crocodiles and alligators), Squamata (snakes and lizards) and Chelonia (turtles and tortoises).

Parietal eye – a median outgrowth of the diencephalon anterior to the pineal gland, having visual adaptations in many amniotes and lizards.

Pelvis – the structure of the vertebrate skeleton supporting the lower limbs in humans and the hind limbs or corresponding parts in other vertebrates.

Phagocyte – any cell that ingests and destroys foreign particles, bacteria, and cell debris.

Pineal gland – a small, cone-shaped organ in the brain of most vertebrates that secretes the hormone melatonin. In some animals it is connected with a rudimentary eye and in other animals it is supposed to be the remnant of a dorsal median eye.

Posterior – at or near the hind end in quadrupeds or toward the spine in primates. 

Protozoa – any of a large group of one-celled organisms (called protists) that live in water or as parasites. Protozoans include the amoebas, flagellates, foraminiferans, and ciliates.

Pupil – the expanding and contracting opening in the iris of the eye, through which light passes to the retina.

Quadruped – a four-footed animal.

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Refraction – the deflection of light, for example, from a straight path.

Retina – the innermost coat of the posterior part of the eyeball that receives the image produced by the lens, is continuous with the optic nerve, and consists of several layers, one of which contains the rod cells and cone cells that are sensitive to light.

Rod cells – one of the rod-shaped cells in the retina of the eye, more sensitive to light than cone cells and responsible for the ability to see in dim light. Do not contribute greatly to the perception of colour.

Rookery – a breeding place or colony of animals, especially birds.

Sclera – a dense, white, fibrous membrane that (with the cornea) forms the external covering of the eyeball.

Sexually dimorphic – where males and females of a species are morphologically different.

Snout-vent length (SVL) – a measurement of size taken from the tip of an animal’s nose to the opening of the cloaca at the tail base.

Sternum – a long flat bone in most vertebrates that is situated along the ventral midline of the thorax.

Tapetum lucidum – a layer in the choroid chiefly of nocturnal animals that reflects light causing the eyes to glow when light strikes them at night and that is made up of several layers of flattened cells covered by a zone of doubly refracting crystals.

Temporal fenestra – a small opening or perforation, as in a bone.

Temperature-dependent sex determination (TSD) – where the sex of an individual is determined by the temperature experienced by embryos during the thermo-sensitive period of development during incubation.

Terrestrial – living on or in the ground.

Tetrapod – having four limbs or descended from four-limbed ancestors.

Thorax - the part of the trunk in higher vertebrates between the neck and the abdomen, containing the cavity, enclosed by the ribs, sternum, and certain vertebrae, in which the heart, lungs, etc., are situated. The chest.

Uncinate process – a curved, bony projection on certain ribs of birds and tuatara that projects backward and overlaps the succeeding rib, serving to strengthen the thorax.

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Vascular – of, characterized by, or containing vessels that carry or circulate fluids, such as blood, lymph, or sap, through the body of an animal or plant.

Ventral - situated on or toward the lower, abdominal plane of the body.

Vertebrate – an organism that has a backbone or spinal column.

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Updated: 11 September, 2007     © 2004 Victoria University of Wellington, New Zealand