Question

Asconoid type of canal system is found in
A. Scypha
B. Leucosolenia
C. Euplectella
D. Hyalonema

Answer 1

Hint: Asconoid is the simplest type canal system found in sponges. This type of canal system is also called the ascon type. This canal system of sponges helps in food acquisition, respiratory gas exchange and in excretion too.

Complete answer: Sponges are multicellular organisms. Their body is composed of pores and channels that allow water to circulate. Usually, in the asconoid type of canal system, Ostia or incurrent pores (these are microscopic apertures) are present on the surface of the body, i.e. they are extended from the external surface to the spongocoel. Ostia is lined by choanocyte cells and the spongocoel opens to the outside through the osculum, so that water that enters the spongocoel through the Ostia will leave through the osculum. The spongocoel is lined by choanocytes.
a) Scypha has a syconoid type or sycon type canal system, which is more advanced than the asconoid type.
b) Euplectella also has a syconoid type canal system.
c) The canal system of Hyalonema is complicated as the spongocoel is absent, but the osculum and ostia are present.
d) Leucosolenia has the asconoid type canal system as it is a sponge. Clathrina is also another example. This type of canal system is found in the adult stages and the Olynthus stage of some calcareous sponges.
Hence, the correct answer is option B.

Note: Ascon type is the simplest type canal system found in sponges. Sponges belong to the phylum Porifera. It is found during some of the developmental stages of all syconoid sponges. The body is vase-like and is symmetrically radial.