A muscular hydrostat is a biological structure, found in animals. It is used to manipulate items (including food), or to move its host about, and is made mainly of muscles, with no skeletal support. It performs its hydraulic movement without fluid in a separate compartment, as in a hydrostatic skeleton. The principle behind the hydrostatic skeleton is that water is incompressible at physiological pressures. Therefore, a fiber-wound chamber full of water will act as a constant-volume system. What makes the muscular hydrostat special is that it relies on the same principle, but there is no water-filled cavity. Instead, the bulk of the organ is made up of muscle, which also has constant volume. Therefore, instead of a cylinder wrapped with muscle and connective tissue that changes its shape, a muscular hydrostat is a cylinder made of muscle. Jump to: navigation, search Phyla Porifera (sponges) Ctenophora (comb jellies) Cnidaria Placozoa Subregnum Bilateria  Acoelomorpha  Orthonectida  Rhombozoa  Myxozoa  Superphylum Deuterostomia     Chordata (vertebrates, etc. ... Jump to: navigation, search A top-down view of skeletal muscle Muscle is a contractile form of tissue. ... Skeleton is also a winter sport: see skeleton (sport). ... Hydraulics is a branch of science and engineering concerned with the use of liquids to perform mechanical tasks. ... A hydrostatic skeleton is one in which the bodys shape and/or function is maintained by an incompressible fluid such as blood or hemolymph. ... A hydrostatic skeleton is one in which the bodys shape and/or function is maintained by an incompressible fluid such as blood or hemolymph. ...

Origin of the name

Muscular hydrostat is a term coined by Dr. William M. Kier in 1982 to characterize the arms of octopuses and the arms and tentacles of squid. In a paper published in 1985, he showed that other organs, such as mammalian and reptile tongues and elephant trunks, fit in the category as well.

Common muscular hydrostats

Ordered by geologic age, oldest first, newest last. Jump to: navigation, search Geology (from Greek γη- (ge-, the earth) and λογος (logos, word, reason)) is the science and study of the Earth, its composition, structure, physical properties, history, and the processes that shape it. ... Jump to: navigation, search The geologic time scale is used by geologists and other scientists to describe the timing and relationships between events that have occurred during the history of the Earth. ...

• Whole bodies of many worms.
• Feet of mollusks, which became:
  • Arms and tentacles of cephalopods such as nautiloids, octopuses, squids.
• Tongues of animals.
• Trunks of elephants.