What is Canal System & Types of Canal Systems - NEET Zoology XI - Animal Kingdom

What is Canal System & types of Canal Systems - NEET Zoology XI - Animal Kingdom Canal System: The body of a sponge is organized to form a complex system of pores and canals called canal system or water transport system or aquiferous system. Aquiferous system and highly totipotent nature of cells are two characteristic features of sponges. Three types of canal systems are found in sponges: (i) Ascon Type. (ii) Sycon Type. (iii) Leucon Type. (i) Ascon Type: It is the simplest type of canal system seen in Leucosolenia and few other sponges. The course taken by water current in ascon type is as follows: Ingressing water ⟶ Canal ⟶ Spongocoel ⟶ Osculum. (ii) Sycon Type: It is more complex than the ascon type. It is seen in Sycon, Grantia and some other sponges. The body wall of syconoid sponges shows two types of canals. They are incurrent canal and radial canal. The course taken by water current in sycon type is as follows: (iii) Leucon Type: It is most complex canal system which is seen in Spongilla. The course taken by water current in leucon type is as follows: Leucon type of canal system presents three successive grades in their evolutionary pattern. They include eurypylous type, aphodal type and diplodal type. Leuconoid - Eurypylous Type: It is the simplest and most primitive type of all leucon types. Leuconoid - Aphodal Type: In this type, apopyle is drawn out as a narrow canal called aphodus. Aphodus connects flagellated chambers with excurrent canals Leuconoid - Diplodal Type: It is seen in fresh water sponges like Spongilla and Oscarella. Besides aphodus, another narrow tube called prosodus is present between the incurrent canal and flagellated chamber In demospongiae, the leuconoid condition is derived from a larval stage, called the rhagon. It is a conical organism with a flattened base. The canal system of rhagon larva does not occur in any adult sponge. Because of its derivation from rhagon stage in demospongiae, the leucon type of canal system is also called the rhagon type. For more such resources go to https://goo.gl/Eh96EY Website: https://www.learnpedia.in/