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The pineal gland, a photosensitive organ regulating melatonin production by capturing light signals through the photoreceptor cell converting them into intercellular signals of the lamprey is located in the midline of its body, for lamprey, the pineal eye is accompanied by the parapineal organ. [38]
A parietal eye (third eye, pineal eye) is a part of the epithalamus in some vertebrates. The eye is at the top of the head; is photoreceptive; and is associated with the pineal gland , which regulates circadian rhythmicity and hormone production for thermoregulation . [ 1 ]
The pineal gland is present in almost all vertebrates, but is absent in protochordates in which there is a simple pineal homologue. The hagfish, archaic vertebrates, lack a pineal gland. [7] In some species of amphibians and reptiles, the gland is linked to a light-sensing organ, variously called the parietal eye, the pineal eye or the third ...
An abundance of cilia and centrioles has also been found in these Type 2 cells of the pineal gland. [7] Unique to the Type 2 is the presence of vacuoles containing 2 layers of membrane. [ 7 ] As Type 1 cells contain serotonin , Type 2 cells contain melatonin and are thought to have similar characteristics as endocrine and neuronal cells.
The sea lamprey has an eel-like body without paired fins. Its mouth is jawless, round and sucker-like, and as wide or wider than the head; sharp teeth are arranged in many concentric circular rows around a sharp, rasp-like tongue. There are seven branchial or gill-like openings behind the eye. Sea lampreys are olive or brown-yellow on the ...
As with all lamprey species, the least brook lamprey spends the majority of its life as a worm-like ammocoete. The ammocoete (5 mm–20 cm) is clear with a pigmented head when small (<5 cm), but becomes a dark/golden brown as it matures. Ammocoetes have pigmented eye spots located in the head that can detect light and dark.
The southern brook lamprey (Ichthyomyzon gagei) is a lamprey found in the Southern United States including Arkansas, Louisiana, Mississippi, Alabama, and Georgia. It is a jawless fish with a sucking mouth on one end of it (like a leech). It can appear to be a small eel, since it is rarely longer than one foot in length.
The Pacific lamprey (Entosphenus tridentatus) is an anadromous parasitic lamprey from the Pacific Coast of North America and Asia in an area called the Pacific Rim. [4] It is a member of the Petromyzontidae family. The Pacific lamprey is also known as the three-tooth lamprey and tridentate lamprey. Ammocoetes held by biologist in the Carmel River