Anatomy
Not being a true phylogenetic group, soft-bodied organism vary enormously in anatomy. Cnidarians and flatworms have a single opening gut and a diffuse nerve system. The roundworms, annelids, molluscs, the various lophoporate phyla and non-vertebrate chordates have a tubular gut open at both ends. While the majority of the soft-bodied animals typically don't have any kind of skeleton, some do, mainly in the form of stiff cuticulas (roundworms, water bears) or hydrostatic skeletons (annelids).
While their lack of a skeleton typically restrict soft-bodied animals' body size on land, but some marine representatives can grow to very large sizes. The heaviest soft-bodied organisms are likely the giant squids, with maximum weight estimated at 275 kilograms (610 lb) for females, while arctic lion's mane jellyfish mat reach comparable sizes. The longest animal on record is also thought to be a soft-bodied organism, a 55 metres (180 ft) long thread-like bootlace worm, Lineus longissimus found on a Scottish beach 1864. Most soft-bodied organisms are much smaller, even microscopic. The various organisms grouped as mesozoans and the curious Placozoa are typically composed of just a few hundred cells.
Read more about this topic: Soft-bodied Organisms
Famous quotes containing the word anatomy:
“Man is a shrewd inventor, and is ever taking the hint of a new machine from his own structure, adapting some secret of his own anatomy in iron, wood, and leather, to some required function in the work of the world.”
—Ralph Waldo Emerson (1803–1882)
“I love to see, when leaves depart,
The clear anatomy arrive,”
—Roy Campbell (1902–1957)
“But a man must keep an eye on his servants, if he would not have them rule him. Man is a shrewd inventor, and is ever taking the hint of a new machine from his own structure, adapting some secret of his own anatomy in iron, wood, and leather, to some required function in the work of the world. But it is found that the machine unmans the user. What he gains in making cloth, he loses in general power.”
—Ralph Waldo Emerson (1803–1882)