See also: Lamellar Body = Pineal Eye Amphioxus Hormones Endostyle = Thyroid
Amphioxus Gut Hormones Amphioxus Pituitary Amphioxus Gonads
Amphioxus Stress Hormones Amphioxus Oxytocin Amphioxus Genomics
Pineal gland (Wiki)
This description of the human pineal is provided for reference.
"Melanopsin is a photopigment found in specialized photosensitive ganglion cells of the retina that are involved in the regulation of circadian rhythms, pupillary light reflex, and other non-visual responses to light. In structure, melanopsin is an opsin, a retinylidene protein variety of G-protein-coupled receptor." "In non-mammalian vertebrates, however, such as birds, fish and amphibians, melanopsin is found in certain other retinal cells, and also outside the retina in structures known or presumed to be directly photosensitive, such as the iris muscle of the eye, deep brain regions, the pineal gland, and the skin."
Localization and partial characterization of melatonin receptors in amphioxus, hagfish, lamprey, and skate.
"Through its secretion of melatonin, the pineal complex of vertebrates exerts a range of physiological effects including regulation of circadian rhythms, seasonal reproduction, metamorphosis, and body color change."
"No specific binding was found in hagfish or amphioxus, which lack a pineal complex."