Most cephalopods have a collection of skin components that interact with light. These may include iridophores, leucophores, chromatophores and (in some species) photophores. 1957, Teichert und Moore 1964, Teichert 1988 and others. The three subclasses are traditional and correspond to the three orders of cephalopods recognized by Bather. [139] Only 29 hours after hatching, the cephalopods were thrown into space, hidden in small “aquarium bags.” Ancient sailors knew about cephalopods, as evidenced by works of art such as a stone carving found in the archaeological reconstruction of Bronze Age Minoan Crete in Knossos (1900 – 1100 BC) depicting a fisherman with an octopus. [147] The terribly powerful gorgon of Greek mythology may have been inspired by the octopus or squid, with the octopus body representing Medusa`s severed head, the beak as the protruding tongue, and the fangs and tentacles like snakes. [148] Surprisingly, given their ability to change color, all octopuses[21] and most cephalopods[22][23] are considered colorblind. Coleoid cephalopods (octopus, squid, squid) have only one type of photoreceptor and do not have the ability to determine color by comparing the intensity of photons detected on multiple spectral channels. When they camouflage themselves, they use their chromatophores to change brightness and patterns based on the background they see, but their ability to adjust the specific color of a background can come from cells like iridophores and leucophores that reflect light from the environment. [24] They also produce visual pigments throughout the body and can perceive light exposure directly from their bodies. [25] Evidence of color vision has been found in the Enope sparkling squid (Watasenia scintillans). [22] [26] It achieves color vision with three photoreceptors based on the same opsin but using different retinal molecules like chromophores: A1 (retinal), A3 (3-dehydroretinian) and A4 (4-hydroxyretinian).
The A1 photoreceptor is most sensitive to green-blue (484 nm), the A2 photoreceptor to blue-green (500 nm) and the A4 photoreceptor to blue (470 nm). [27] Britannica.com: Encyclopedia article on cephalopods A cephalopod /ˈsɛfələpɒd/ is any member of the mollusc class Cephalopoda /sɛfəˈlɒpədə/ (Greek plural κεφαλόποδες, kephalópods; “Cephalopods”)[3] such as an octopus, squid, squid or nautilus. These exclusively marine animals are characterized by bilateral body symmetry, a prominent head and a series of arms or tentacles (muscle hydrostats) modified by the foot of primitive mollusc. Fishermen sometimes call cephalopods “squid,” which refers to their common ability to inject ink. The study of cephalopods is a branch of malacology known as teuthology. Cephalopods are widely considered the most intelligent of invertebrates and have well-developed senses and a large brain (larger than those of gastropods). [9] The nervous system of cephalopods is the most complex of invertebrates[10][11] and their brain-body mass ratio is between that of endothermic and ectothermic vertebrates. [8]: It is also known that 14 captive cephalopods come out of their aquariums, maneuver at a distance from the laboratory floor, enter another aquarium to feed on the crabs and return to their own aquarium. [12] With the exception of Nautilidae and octopus species belonging to the suborder Cirrina,[40] all known cephalopods have an ink bag that can be used to eject a cloud of dark ink to confuse predators. [21] This sac is a muscle sac that was created as an extension of the hind intestine. It is located under the intestine and opens into the anus, into which its contents – almost pure melanin – can be injected; Its proximity to the base of the funnel means that the ink can be dispensed by the expelled water when the cephalopod uses its jet drive.
[21] The ejected melanin cloud is usually mixed with mucus produced elsewhere in the mantle during expulsion, and thus forms a thick cloud, resulting in visual (and possibly chemosensory) impairment of the predator, such as a smokescreen. However, a more sophisticated behavior has been observed, in which the cephalopod releases a cloud with a higher mucus content, roughly similar to the cephalopod that released it (this lure is called pseudomorph). This strategy often results in the predator attacking the pseudomorph rather than its rapidly departing prey. [21] For more information, see Ink behavior. Early cephalopods were probably predators at the top of the food chain. [21] After the late extinction of the Cambrian that led to the disappearance of many anomalocarids, predatory niches became available for other animals. [119] During the Ordovician, primitive cephalopods underwent impulses of diversification[120] to become diverse and dominant in the Paleozoic and Mesozoic. [121] one of a class of molluscs characterized by the attachment of tentacles to a particular head, 1825, from French cephalopod, from the modern Latin cephalopoda (the class name), from the Greek kephalē “head” (see cephalo-) + pod-, stem of lice “foot” (from the root PIE *ped- “foot”).