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Whereas fish or crustaceans brought up from such depths inevitably arrive dead, a nautilus will be unfazed despite the pressure change of as much as 80 standard atmospheres (1,200 psi). The exact reasons for this ability, which is thought to be coincidental rather than specifically functional, are not known, though the perforated structure of ...
Mollusca is a phylum of protostomic invertebrate animals, whose members are known as molluscs or mollusks [a] (/ ˈ m ɒ l ə s k s /). Around 76,000 extant species of molluscs are recognized, making it the second-largest animal phylum after Arthropoda . [ 5 ]
The taxonomic term Bivalvia was first used by Linnaeus in the 10th edition of his Systema Naturae in 1758 to refer to animals having shells composed of two valves. [3] More recently, the class was known as Pelecypoda, meaning "axe-foot" (based on the shape of the foot of the animal when extended).
The internal anatomy is visible, including the paired siphons to the right A siphon is an anatomical structure which is part of the body of aquatic molluscs in three classes : Gastropoda , Bivalvia and Cephalopoda (members of these classes include saltwater and freshwater snails , clams , octopus , squid and relatives).
In some mollusks the mantle cavity is a brood chamber, and in cephalopods and some bivalves such as scallops, it is a locomotory organ. The mantle is highly muscular. In cephalopods the contraction of the mantle is used to force water through a tubular siphon, the hyponome , and this propels the animal very rapidly through the water.
Mussel (/ ˈ m ʌ s ə l /) is the common name used for members of several families of bivalve molluscs, from saltwater and freshwater habitats. These groups have in common a shell whose outline is elongated and asymmetrical compared with other edible clams, which are often more or less rounded or oval.
The lower right portion of this image shows a Venerupis senegalensis with a distinct pallial sinus on the viewer's right side/ animal's right valve which points towards the animal's posterior The oldest point of a bivalve shell is called the beak , and the raised area around it is known as the umbo (plural umbones ). [ 9 ]
In practice, fish anatomy and fish physiology complement each other, the former dealing with the structure of a fish, its organs or component parts and how they are put together, such as might be observed on the dissecting table or under the microscope, and the latter dealing with how those components function together in living fish. The ...