Is the cuttlefish a mollusk?
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Cuttlefish or cuttles are marine molluscs of the order Sepiida. They belong to the class Cephalopoda, which also includes squid, octopuses, and nautiluses. Cuttlefish have a unique internal shell, the cuttlebone.
Cuttlefish
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Two submarines of the United States Navy have been named Cuttlefish for the cuttlefish, a ten-armed marine mollusk similar to the squid.
USS Cuttlefish
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The blood of a cuttlefish is an unusual shade of green-blue, because it uses the copper-containing protein haemocyanin to carry oxygen instead of the red, iron-containing protein haemoglobin found in vertebrates' blood. The blood is pumped by three separate hearts: two branchial hearts pump blood to the cuttlefish's pair of gills (one heart for each), and the third pumps blood around the rest of the body. Cuttlefish blood must flow more rapidly than that of most other animals because haemocyanin carries substantially less oxygen than haemoglobin. Unlike most other mollusks, cephalopods like cuttlefish have a closed circulatory system.
Cuttlefish
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Like other marine mollusks, cuttlefish have ink stores that are used for chemical deterrence, phagomimicry, sensory distraction, and evasion when attacked. The composition of the ink leads to a richly colored "black" ink which is rich in ammonium salts and amino acids that may have a role in phagomimicry defenses.
Cuttlefish
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Idiosepiidae is a family of mollusk in the class Cephalopoda. This family appears to be related to the cuttlefish in the order Sepiida and the bobtail squid in the order Sepiolida but the exact placement of this family within the Decapodiformes is "incertae sedis".
Idiosepiidae
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"B-2" was laid down by Fore River Shipbuilding Company in Quincy, Massachusetts, under subcontract from Electric Boat Company of New Suffolk, L. I., as Cuttlefish, making her the first ship of the United States Navy to be named for the cuttlefish, a 10-armed marine mollusk similar to the squid.
USS B-2 (SS-11)
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Cuttlefish eat small molluscs, crabs, shrimp, fish, octopus, worms, and other cuttlefish. Their predators include dolphins, sharks, fish, seals, seabirds, and other cuttlefish. The average life expectancy of a cuttlefish is about 1–2 years. Recent studies indicate cuttlefish are among the most intelligent invertebrates. Cuttlefish also have one of the largest brain-to-body size ratios of all invertebrates.
Cuttlefish
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The common cuttlefish is one of the largest species of cuttlefish with their mantles (does not include their head and arms) reaching upwards of 45 cm. The mantle houses the reproductive and digestive tracts of the cuttlefish and is also home to an internal shell called the cuttlebone. The common cuttlefish has two highly developed eyes, eight arms which are located around the mouth and are used to hold and move prey, two tentacles which are used to quickly capture prey, and a radula which is used to tear and rip apart any prey they have captured. Cuttlefish are well known for their unmatched camouflaging abilities which are possible due to light scattering leucophores, pigmented chromatophore organs, and structurally reflecting iridophores all located in their skin. These specialized characteristics give them the ability to not only change their colour, but also change the texture appearance of their skin and all of this is done despite them being colour-blind. Their camouflaging abilities are categorized into four main types including mottle, stipple, uniform, and disruptive. These complex camouflage abilities are not just present in adult cuttlefish, but cuttlefish juveniles also contain these complicated characteristics which allows them to be able to camouflage from a young age.
Common cuttlefish
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During the day, most cuttlefish can be found buried below the substrate and fairly inactive. At night however, they are actively searching for prey and can ambush their prey from under the substrate. Cuttlefish are carnivorous and eat a variety or organisms including crustaceans (crabs and shrimp), small fish, molluscs (clams and snails), and sometimes other cuttlefish which is more commonly seen when the abundance of other prey is low.
Common cuttlefish
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"S. apama" is a neritic demersal species. They are carnivorous, opportunistic and voracious predators who feed predominantly on crustaceans and fish. Using neurally controlled cells known as chromatophore organs (red to yellow), iridophores (iridescent: spans the entire visible spectrum from blue to near-IR) and leucophores (white), the cuttlefish can put on spectacular displays, changing colour and patterns in a fraction of a second. Located in three layers under the skin, leucophores make up the bottom layer, with chromatophores the outermost. By selective blocking, the three layers work together to produce polarised patterns. Unlike those in most animals, cuttlefish iridophores are physiologically active; they can change their reflectivity, and the degree of polarisation can also be controlled. Cuttlefish are colourblind; however, the photoreceptors of cuttlefish eyes are arranged in a way which gives them the ability to see the linear polarisation of light. While the mantis shrimp is the only known creature to have true polarisation vision, cephalopods may also. Because the optic lobes of cuttlefish are larger than any other region of the brain and their skin produces polarised reflective patterns, they may communicate through this visual system. By raising elaborate papillae on their skin, "S. apama" squid can change the shape and the texture of their skin to imitate rock, sand, or seaweed.
Sepia apama