Question

Q- describe life history of polystomella.

Answer 1

LIFE HISTORY OF POLYSTOMELLA(ELPHIDIUM)
Life history of Polystomella shows alternation of generations (Sexual method of reproduction will alternate with asexual method of reproduction).

Elphidium-Asexual reproduction :

in Elphidium microspheric form takes up asexual reproduction by multiple fission. The nuclei break into many Chromatin bits. They become round. They are covered by bits of cytoplasm. Several amoeboid cells are formed. These amoebulae are liberated into water. In the water these Amoebulae will develop shell. The first chamber is called 'Proloculum'.

This grows into megalospheric form. It contains only single nucleus. This takes up sexual reproduction.