Search results
Results from the WOW.Com Content Network
Morphological change is the result of a change in the density of pigment containing cells and tends to change over longer periods of time. Physiological change, the kind observed in cephalopod lineages, is typically the result of the movement of pigment within the chromatophore, changing where different pigments are localized within the cell.
Reflectin proteins are likely distributed in the outer layer of cells called "sheath cells" that surround an organism's pigment cells also known as chromatocyte. [2] Specific sequences of reflectin ables cephalopods to communicate and camouflage by adjusting color and reflectivity. [3]
Coleoid cephalopods (including octopuses, squids and cuttlefish) have complex multicellular organs that they use to change colour rapidly, producing a wide variety of bright colours and patterns. Each chromatophore unit is composed of a single chromatophore cell and numerous muscle, nerve, glial , and sheath cells. [ 43 ]
Diagram of a cephalopod's photophore, in vertical section. A photophore is a glandular organ that appears as luminous spots on marine animals, including fish and cephalopods. The organ can be simple, or as complex as the human eye, equipped with lenses, shutters, color filters, and reflectors; unlike an eye, however, it is optimized to produce ...
Cephalopods are able to communicate visually using a diverse range of signals. To produce these signals, cephalopods can vary four types of communication elements: chromatic (skin coloration), skin texture (e.g. rough or smooth), posture, and locomotion. Changes in body appearance such as these are sometimes called polyphenism. [21]
The cephalopods were once thought to have evolved from a monoplacophoran-like ancestor [8] with a curved, tapering shell, [9] and to be closely related to the gastropods (snails). [10] The similarity of the early shelled cephalopod Plectronoceras to some gastropods was used to support this view.
Probably, photoreceptor cells existed long before the Cambrian explosion. [13] Higher-level similarities – such as the use of the protein crystallin in the independently derived cephalopod and vertebrate lenses [14] – reflect the co-option of a more fundamental protein to a new function within the eye. [15]
Good evidence exists for the appearance of gastropods, cephalopods and bivalves in the Cambrian period . However, the evolutionary history both of the emergence of molluscs from the ancestral group Lophotrochozoa, and of their diversification into the well-known living and fossil forms, is still vigorously debated.