oceany: Squid

Evidence: 100 • authority: 72

A squid (pl. squid) is a mollusc with an elongated soft body, large eyes, eight arms, and two tentacles in the orders Myopsida, Oegopsida, and Bathyteuthida (though many other molluscs within the broader Neocoleoidea are also called squid despite not strictly fitting these criteria). Like all other cephalopods, squid have a distinct head, bilateral symmetry, and a mantle. They are mainly soft-bodied, like octopuses, but have a small internal skeleton in the form of a rod-like gladius or pen, made of chitin. Squid diverged from other cephalopods during the Jurassic and radiated at the beginning of the Late Cretaceous, and occupy a similar role to teleost fish as open-water predators of simil…

Evidence: 84 • authority: 72

Chromatophores are cells that produce color, of which many types are pigment-containing cells, or groups of cells, found in a wide range of animals including amphibians, fish, reptiles, crustaceans and cephalopods. Mammals and birds, in contrast, have a class of cells called melanocytes for coloration. Chromatophores are largely responsible for generating skin and eye colour in ectothermic animals and are generated in the neural crest during embryonic development. Mature chromatophores are grouped into subclasses based on their colour under white light: xanthophores (yellow), erythrophores (red), iridophores (reflective / iridescent), leucophores (white), melanophores (black/brown), and cya…

Evidence: 84 • authority: 72

Underwater camouflage is the set of methods of achieving crypsis—avoidance of observation—that allows otherwise visible aquatic organisms to remain unnoticed by other organisms such as predators or prey. Camouflage in large bodies of water differs markedly from camouflage on land. The environment is essentially the same on all sides. Light always falls from above, and there is generally no variable background to compare with trees and bushes. Near to the sea surface reflectivity and blue coloration are the most common form of camouflage. Below, countershading is more common, with blue coloration on the dorsal side and white on the ventral side. Below the epipelagic zone transparency is more…

Evidence: 67 • authority: 88

Squid use Bragg reflectors in their skin to change colour. Using a microscopy technique known as holotomography, scientists at the Marine Biological Laboratory in Woods Hole, Massachusetts, have found that the tuneable optical properties of squid skin stem from winding columns of platelets in certain cells.

Evidence: 67 • authority: 72

Camouflage is the use of any combination of materials, coloration, or illumination for concealment, either by making animals or objects hard to see, or by disguising them as something else. Examples include the leopard's spotted coat, the battledress of a modern soldier, and the leaf-mimic katydid's wings. A third approach, motion dazzle, confuses the observer with a conspicuous pattern, making the object visible but momentarily harder to locate. The majority of camouflage methods aim for crypsis, often through a general resemblance to the background, high contrast disruptive coloration, eliminating shadow, and countershading. In the open ocean, where there is no background, the principal m…

Evidence: 51 • authority: 80

Squid flicker and flash for communication and camouflage

Evidence: 51 • authority: 80

Multiple calcium signalling pathways in squid giant presynaptic terminals

Evidence: 51 • authority: 92

Embryonic development of a centralised brain in coleoid cephalopods.. The last common ancestor of cephalopods and vertebrates lived about 580 million years ago, yet coleoid cephalopods, comprising squid, cuttlefish and octopus, have evolved an extraordinary behavioural repertoire that includes learned behaviour and tool utilization. These animals also developed innovative advanced defence mechanisms such as camouflage and ink release. They have evolved unique life cycles and possess the largest invertebrate nervous systems. Thus, studying coleoid cephalopods provides a unique opportunity to gain insights into the evolution and development of large centralised nervous systems. As non-model s…

Evidence: 51 • authority: 72

Sepioteuthis lessoniana, commonly known as the bigfin reef squid, tiger squid, glitter squid, oval squid, or northern calamari, is a species complex in the loliginid squid family. It is one of the three currently recognized species belonging to the genus Sepioteuthis. Studies in 1993, however, have indicated that bigfin reef squids may comprise several cryptic species, that are very similar and closely related. Bigfin reef squids are characterised by a large oval fin that extends throughout the margins of its mantle, giving them a superficial similarity to cuttlefish. They are small to medium-sized squids, averaging 3.8 to 33 centimetres (1.5 to 13.0 in) in length. They exhibit elaborate ma…

Evidence: — • authority: 92

Environmental control of morphological color changes in the Bigfin Reef Squid, Sepioteuthis lessoniana. ABSTRACT Phenotypic plasticity enables organisms to adjust their traits in response to environmental conditions, yet studies of animal coloration—particularly in cephalopods—have largely focused on rapid neural control while overlooking slower, substrate-level changes. Here, we investigate whether morphological color change contributes to phenotypic plasticity in the bigfin reef squid ( Sepioteuthis lessoniana ). Hatchlings were reared in contrasting light (white) and dark (black) environments for 14 weeks, and chromatophore organization was quantified across developmental stages (4, 9, a…

Evidence: — • authority: 92

Situational motionless camouflage of a loliginid squid.. Coleoid cephalopods have the most elaborate camouflage system in the animal kingdom. This enables them to hide from or deceive both predators and prey. Most studies have focused on benthic species of octopus and cuttlefish, while studies on squid focused mainly on the chromatophore system for communication. Camouflage adaptations to the substrate while moving has been recently described in the semi-pelagic oval squid (Sepioteuthis lessoniana). Our current study focuses on the same squid's complex camouflage to substrate in a stationary, motionless position. We observed disruptive, uniform, and mottled chromatic body patterns, and we i…

Evidence: — • authority: 92

Metabolomic Profiling of Squid Chromatophores Reveals Differential Biochemical Fingerprints across Red, Yellow, and Brown Colors.. Cephalopods possess the ability to camouflage using specialized dermal organs, including chromatophores that modulate pigment-based color, iridophores that produce structural iridescence, and leucophores that scatter light to create diffuse white. Among these organs, chromatophores─present as yellow, red, and brown variants─contribute to rapid color changes during camouflage, as their multicellular architecture expands under neuromuscular control. While the general structure and function of chromatophores have been characterized, the specific biochemical feature…