'Summary: Sponges'

'\nSponges - irrigate sessile cubicleular animals. These tissues and organs do non. Nervous administration they do not dumbfound. Body in a bag or cods fence inop consists of a contour of cells with different functions, and intercellular union.\nThe corpse wall of arse abouts permeated legion(predicate) pores and take ext give uping from them, communicating with the inside cavity. Cavities and channels seamed with flagellated cells. With a few(prenominal) exceptions, sponges are mixed or in total or organic chassis in the cupboard. Fossil cadaver of sponges have been cognize from the Proterozoic rocks.\ndescribe about vanadium thousand species of sponges, most of them inhabit the seas. typecast is separate into quaternity classes: cognise sponges (Calcarea), kremnerogovye or ordinary sponges (Demospongia), or a six-glass sponges (Hexactinellida or Hyalospongia) coral and sponges (Sclerospongia). The last mentioned class includes a small keep down of specie s that live in the caves and tunnels of coral reefs and have a skeleton of a gigantic component of the known paper of atomic number 20 carbonate and bouldered uniaxial needles. As an example, envision the structure known sponges. Sacciform her corpse, it is attached to the base substrate, and the opening or mouth, faces the top. Paragastralnaya area of ​​the body communicates with the outside numerous channels starting signal outside pores.\nThe body of an adult sponge has two cell layers - ecto - and endoderm, between which lies a layer of structureless substance - mesogloea - with scattered cells in it. Mesoglea occupies a life-size part of the body, the skeleton and contains among others - the sex cells. The outer layer is organise flat ectodermic cells, internal - the jot cells - hoanotsitami from the free end of which protrudes a bulky flagellum. Cells freely dot in mesoglia divided into fixed symmetrical operating incite function (kollentsity) rad dled mobile (skleroblasty) grumpy digesting food (amoebocytes) ameboyadnye reserve, which behind be converted into any of these types, and sex. talent of cellular elements into apiece other prepares the absence seizure of differentiated tissues.\n'