Information about Parietal Eye
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Tuataras have a well-developed (but only seen in hatchlings) parietal eye.
A parietal eye, also known as a parietal organ or third-eye is a part of the epithalamus present in some animal species. The eye may be photoreceptive and is usually associated with the pineal gland, regulating circadian rhythmicity and hormone production for thermoregulation.[1]
Function
The lizard-like reptile tuatara has a "well-developed parietal eye, with small lens and retina".[2] Parietal eyes are also found in lizards, frogs and lampreys, as well as some species of fish, such as tuna and pelagic sharks, where it is visible as a light-sensitive spot on top of their head. A poorly developed version, often called the parapineal gland, occurs in salamanders. In birds and mammals the parietal organ (but not the pineal gland) is absent.Physiology
The parietal eye is a part of the epithalamus, which can be divided into two major parts; the epiphysis (the pineal organ, or pineal gland if mostly endocrine) and the parietal organ, often called the parietal eye, or third eye, if photoreceptive. It arises as an anterior evagination of the pineal organ or as a separate outgrowth of the roof of the diencephalon. In some species, it protrudes through the skull.[3] The parietal eye uses a different biochemical method of detecting light than rod cells or cone cells in a normal eye.[4]References
1. ^ Eakin, R. M (1973). The Third Eye. Berkeley: University of California Press.
2. ^ Uetz, Peter (7 Oct 2003). Sphenodontidae. The EMBL reptile database. European Molecular Biology Laboratory, heidelberg. Retrieved on 2007-2-22.
3. ^ Zug, George; Vitt, Laurie Vitt; and Caldwell, Janalee (2002). Herpetology: An Introductory Biology of Amphibians and Reptiles, Second Edition. San Diego: Academic Press, 75. 0-12-782622-X.
4. ^ Xiong, Wei-Hong; Solessio,Eduardo C.; and Yau, King-Wai (1998). "An unusual cGMP pathway underlying depolarizing light response of the vertebrate parietal-eye photoreceptor". Nature Neuroscience 1: 359-65. Retrieved on 2007-2-22.
2. ^ Uetz, Peter (7 Oct 2003). Sphenodontidae. The EMBL reptile database. European Molecular Biology Laboratory, heidelberg. Retrieved on 2007-2-22.
3. ^ Zug, George; Vitt, Laurie Vitt; and Caldwell, Janalee (2002). Herpetology: An Introductory Biology of Amphibians and Reptiles, Second Edition. San Diego: Academic Press, 75. 0-12-782622-X.
4. ^ Xiong, Wei-Hong; Solessio,Eduardo C.; and Yau, King-Wai (1998). "An unusual cGMP pathway underlying depolarizing light response of the vertebrate parietal-eye photoreceptor". Nature Neuroscience 1: 359-65. Retrieved on 2007-2-22.
The epithalamus is a dorsal posterior segment of the diencephalon (a segment in the middle of the brain also containing the hypothalamus and the thalamus) which includes the habenula, the stria medullaris and the pineal body.
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The pineal gland (also called the pineal body, epiphysis cerebri, or epiphysis) is a small endocrine gland in the brain. It is shaped like a tiny pine cone, and is located near the center of the brain, between the two hemispheres, tucked in a groove where the
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A circadian rhythm is a roughly-24-hour cycle in the physiological processes of living beings, including plants, animals, fungi and cyanobacteria. The term "circadian", coined by Franz Halberg,[1] comes from the Latin circa, "around", and diem or
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Thermoregulation is the ability of an organism to keep its body temperature within certain boundaries, even when temperature surrounding is very different. This process is one aspect of homeostasis: a dynamic state of stability between an animal's internal environment and its
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Sphenodon
Gray, 1831
Species
Sphenodon punctatus (Gray, 1842)
Sphenodon guntheri (Buller, 1877)
Sphenodon diversum
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Gray, 1831
black: range (North Island, New Zealand)
Species
Sphenodon punctatus (Gray, 1842)
Sphenodon guntheri (Buller, 1877)
Sphenodon diversum
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Lacertilia*
Günther, 1867
Families
Many, see text.
Lizards are reptiles of the order Squamata, normally possessing four legs, external ear openings and movable eyelids.
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Günther, 1867
Families
Many, see text.
Lizards are reptiles of the order Squamata, normally possessing four legs, external ear openings and movable eyelids.
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FROG
General
Dianelos Georgoudis, Damian Leroux, and Billy Simón Chaves
1998
Cipher detail
Key size(s):| 128, 192, or 256 bits
Block size(s):| 128 bits
8
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General
Dianelos Georgoudis, Damian Leroux, and Billy Simón Chaves
1998
Cipher detail
Key size(s):| 128, 192, or 256 bits
Block size(s):| 128 bits
8
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Petromyzontiformes
Family: Petromyzontidae
Subfamilies
Geotriinae
Mordaciinae
Petromyzontinae
A lamprey (sometimes also called lamprey eel
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Family: Petromyzontidae
Subfamilies
Geotriinae
Mordaciinae
Petromyzontinae
A lamprey (sometimes also called lamprey eel
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Tuna are several species of ocean-dwelling fish in the family Scombridae, mostly in the genus Thunnus. Some tuna are able to inhabit freshwater environs as well. Tunas are fast swimmers—they have been clocked at 77 km/h (48 mph)—and include several species that
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SHARK
General
Vincent Rijmen, Joan Daemen, Bart Preneel, Antoon Bosselaers, Erik De Win
1996
KHAZAD, Rijndael
Cipher detail
Key size(s):| 128 bits
Block size(s):| 64 bits
Substitution-permutation network
6
In cryptography,
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General
Vincent Rijmen, Joan Daemen, Bart Preneel, Antoon Bosselaers, Erik De Win
1996
KHAZAD, Rijndael
Cipher detail
Key size(s):| 128 bits
Block size(s):| 64 bits
Substitution-permutation network
6
In cryptography,
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Caudata/Urodela
Suborders
Cryptobranchoidea
Salamandroidea
Sirenoidea
Salamander (orig. from Persian: sām, Fire, and andarūn, Within) is the common name applied to approximately 500 species
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Suborders
Cryptobranchoidea
Salamandroidea
Sirenoidea
Salamander (orig. from Persian: sām, Fire, and andarūn, Within) is the common name applied to approximately 500 species
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Aves
Linnaeus, 1758
Orders
About two dozen - see section below
Birds (class Aves) are bipedal, warm-blooded, egg-laying vertebrate animals.
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Linnaeus, 1758
Orders
About two dozen - see section below
Birds (class Aves) are bipedal, warm-blooded, egg-laying vertebrate animals.
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Mammalia
Linnaeus, 1758
Subclasses & Infraclasses
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Linnaeus, 1758
Subclasses & Infraclasses
- Subclass †Allotheria*
- Subclass Prototheria
- Subclass Theria
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The epithalamus is a dorsal posterior segment of the diencephalon (a segment in the middle of the brain also containing the hypothalamus and the thalamus) which includes the habenula, the stria medullaris and the pineal body.
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Epiphysis is the name for a rounded end of a long bone. The epiphysis is filled with red marrow, which produces erythrocytes, or red blood cells. Located in the epiphysis is the epiphysial plate, also known as the growth plate.
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The pineal gland (also called the pineal body, epiphysis cerebri, or epiphysis) is a small endocrine gland in the brain. It is shaped like a tiny pine cone, and is located near the center of the brain, between the two hemispheres, tucked in a groove where the
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parietal eye, also known as a parietal organ or third-eye is a part of the epithalamus present in some animal species. The eye may be photoreceptive and is usually associated with the pineal gland, regulating circadian rhythmicity and hormone production for
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The diencephalon is the region of the brain that includes the thalamus, hypothalamus, epithalamus, prethalamus or subthalamus and pretectum. It is derived from the prosencephalon. The diencephalon is located at the midline of the brain, above the mesencephalon of the brain stem.
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skull is a bony structure found in many animals which serves as the general framework for the head. The skull supports the structures of the face and protects the head against injury.
The skull can be subdivided into two parts: the cranium and the mandible.
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The skull can be subdivided into two parts: the cranium and the mandible.
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Location Retina
Function Low light photoreceptor
Morphology rod shaped
Presynaptic connections None
Postsynaptic connections Bipolar Cells and Horizontal cells
Rod cells, or rods
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Function Low light photoreceptor
Morphology rod shaped
Presynaptic connections None
Postsynaptic connections Bipolar Cells and Horizontal cells
Rod cells, or rods
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Cone cells, or cones, are photoreceptor cells in the retina of the eye which function best in relatively bright light. The cone cells gradually become more sparse towards the periphery of the retina.
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