Instruct: Given a question, retrieve relevant passages that answer the question.
Query: Is the cuttlefish a mollusk?
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.
These penguins feed on krill, squid, octopus, lantern fish, mollusks, plankton, cuttlefish, and mainly crustaceans.
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.
The siphuncle is a strand of tissue passing longitudinally through the shell of a cephalopod mollusk. Only cephalopods with chambered shells have siphuncles, such as the extinct ammonites and belemnites, and the living nautiluses, cuttlefish, and "Spirula". In the case of the cuttlefish, the siphuncle is indistinct and connects all the small chambers of that animal's highly modified shell; in the other cephalopods it is thread-like and passes through small openings in the walls dividing the chambers.
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.
Some cephalopods such as "Sepia", the cuttlefish, have a large internal shell, the cuttlefish bone, and this often washes up on beaches in parts of the world where cuttlefish are common.
Cuttlefish are indeterminate growers, so smaller cuttlefish always have a chance at finding a mate the next year when they are bigger.[27] Additionally, cuttlefish unable to win in a direct confrontation with a guard male have been observed employing several other tactics to acquire a mate. The most successful of these methods is camouflage; smaller cuttlefish use their camouflage abilities to disguise themselves as a female cuttlefish. Changing their body color, and even pretending to be holding an egg sack, disguised males are able to swim past the larger guard male and mate with the female.[26][28][29]
Cuttlefish are quite popular in Europe. For example, in northeast Italy, they are used in risotto al nero di seppia (risotto with cuttlefish ink), also found in Croatia and Montenegro as crni rižot (black risotto). Catalan cuisine, especially that of the coastal regions, uses cuttlefish and squid ink in a variety of tapas and dishes such as arròs negre. Breaded and deep-fried cuttlefish is a popular dish in Andalusia. In Portugal, cuttlefish is present in many popular dishes. Chocos com tinta (cuttlefish in black ink), for example, is grilled cuttlefish in a sauce of its own ink. Cuttlefish is also popular in the region of Setúbal, where it is served as deep-fried strips or in a variant of feijoada, with white beans. Black pasta is often made using cuttlefish ink.
The common cuttlefish (Sepia officinalis) is the best-known cuttlefish species Hooded cuttlefish (Sepia prashadi) Engravings by the Dutch zoologist Albertus Seba, 1665–1736
Sepia apama, also known as the giant cuttlefish and Australian giant cuttlefish, is the world's largest cuttlefish species, growing to 50 cm (20 in) in mantle length and over in weight. Using cells known as chromatophores, the cuttlefish can put on spectacular displays, changing color in an instant.
Pharaoh cuttlefish often show a solid color when resting on a solid color background, alternating from a pale white to all dark brown. Additionally, they can show a mottled white and brown color, with a center circle of brown. The mechanism for color is the same in the Pharaoh cuttlefish as it is in other cuttlefish. This colour-changing function is produced by groups of red, yellow, brown, and black pigmented chromatophores above a layer of reflective blue and green tinted iridophores and leucophores, with up to 200 of these specialized pigment cells per square millimeter. These sacs of color are controlled by rings of muscle around the sac. The cuttlefish expands and contracts these muscle rings in order to show different colors.
The pharaoh cuttlefish is native to at least the western Indian Ocean, including the Red Sea and Persian Gulf. Of all the cuttlefish species in the Persian Gulf, it is the most commonly caught. When hunting at night, it swims up to shallower parts of the sea to feast on a variety of smaller fish, crabs, and occasionally other cuttlefish. It is thought to have reached the Mediterranean Sea as a Lessepsian migrant via the Suez Canal after many of its cuttlebones were washed up on beaches in Israel in the early 2000s.
Like other marine mollusks, cuttlefish have ink stores that are used for chemical deterrence, phagomimicry, sensory distraction, and evasion when attacked.[20] 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.[20]
An ink sac is an anatomical feature that is found in many cephalopod mollusks used to produce the defensive cephalopod ink. With the exception of nocturnal and very deep water cephalopods, all coeloids (squid, octopus and cuttlefish) which dwell in light conditions have an ink sac, which can be used to expel a cloud of dark ink in order to confuse predators. 
The words mollusc and mollusk are both derived from the French "mollusque", which originated from the Latin "molluscus", from "mollis", soft. "Molluscus" was itself an adaptation of Aristotle's "ta malákia" ("lit." "the soft ones"; < "malakós" "soft"), which he applied inter alia to cuttlefish. The scientific study of molluscs is accordingly called malacology.
It is a commonly fished species of cuttlefish in the Philippines, as well as the most economically important cuttlefish in the northern Indian Ocean. It is often eaten by humans in these areas. Typically, cuttlefish is consumed as dried, shredded cuttlefish, a popular snack food. And, in the Qing Dynasty manual of Chinese gastronomy, the Suiyuan shidan, the roe of the cuttlefish is considered a difficult to prepare but sought-after delicacy. This species is also being harvested by fishermen as a commercial species in the Suez Canal, Egypt.
Cuttlefish or cuttles[2] 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.
"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.
The 2014 event's mascot was Stobie the Disco Cuttlefish, a 13 m long street performance puppet inspired by the Giant Australian Cuttlefish of South Australia. Stobie the Disco Cuttlefish flashed multi-coloured lights, waved its tentacles and played pre-recorded disco music while a group of professional dancers performed original choreography each Saturday night during the event. Public participation was invited and a video teaching the steps to a dance called 'The Cuttlefish' was available online.
A seafood rice dish is the "risotto alla pescatora" ("Fisherman's risotto"), prepared with various mollusks (different types of clams, squids, cuttlefishes), shrimps and a broth made from the boiling of seafood shells.
Cuttlefish sometimes use their color patterns to signal future intent to other cuttlefish. For example, during agonistic encounters, male cuttlefish adopt a pattern called the intense zebra pattern, considered to be an honest signal. If a male is intending to attack, it adopts a "dark face" change, otherwise, it remains pale.[46]
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.[4] Cuttlefish also have one of the largest brain-to-body size ratios of all invertebrates.[4]
The Kamchatka flounder's diet consists of fish and zoobenthos organisms such as squid, cuttlefish, shrimps, prawns, amphipods, mysids, mollusks and marine worms, though the most important prey item is the walleye pollock, which accounted for 56-86% of stomach contents by weight in one study.
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".
The pharaoh cuttlefish ("Sepia pharaonis") is a large cuttlefish species, growing to 42 cm in mantle length and 5 kg in weight.