3The Sponges Phylum Porifera (Latin porous, “pore”; ferre : “to bear”). About 5,500 living species most marine although there are about 200 freshwater species; 30 freshwater species in the US.
4Characteristics of Sponges Metazoa: without true tissue. Cellular grade of complexity (Parazoa).Adults asymmetrical or superficially radialy symmetrical.Unique flagellated cells the choanocytes that drive water through canals and chambers: the aquiferous system.Adults sessile suspension feeders; larval stages are motile.Reproduction sexual or asexual.
6The Poriferan Bauplan Two unique organizational attributes: The aquiferous systemHighly totipotent nature of sponge cells
7Overview of general structures Sponges move water through their bodies using choanocytesAll cells are loosely arranged into a gelatinous matrix, the mesohyleWater enters small holes called ostiaWater exits large holes called osculaA skeleton helps maintain the structure of the sponge.
8Body Structure and the Aquiferous System The mesohyl includes a non cellular coloidal mesoglea in which are embedded collagen fibers, spicules and various cells.Most of these cells are able to change from one type to another as required.Water flows through the ostia all the chanels and eventually out through the osculum.Dermal pores or ostia3)
9Types of Canal SystemsMost sponges can be separated based on their type of canal system.1. Asconoid2. Syconoid3. Leuconoid
10Asconoid spongesFound in radially symmetrical calcarous sponges: rarely exceed 10cm in height.
11Asconoid sponges Simple organization Water moves through the ostia into the spongocoelChoanoderm simple and continuous one cell thick.
12Syconoid spongesSyconoid condition: simple folding of the pinacoderm and choanoderm.As complexity increases the mesohyl may thicken and appear to have two layers.Water is brought in through the incurrent canals and then to radial canals (lined with choanocytes).
41Demospongiae Common sponges Skeleton is variable Can be large Spicules SponginbothCan be large
42Siliceous Spiculse in Desmospongia Never six-rayedMicroscleresMegascleres
43The Big Picture Sponges are metazoans, but don’t have true tissues They are an ancient group (dead end)Three main groups (taxonomic), which fall into three main structural groupsFour types of specialized cells *Choanocyte*