Phylum Poifera

INTRODUCTION:

Phylum phylum Porifera is the simplest and is considered the close primitive of the multicellular animals.

NAME:

The word Porifera is derived from Latin.Porus means revolve about and ferra means to bear.So,the Poriferas atomic number 18 pore-bearing animals,commonly called the

sponges.

HABITAT:

All Poriferas ar aquatic.Out of total 5000 species,150 species live in fresh water art object all others be marine.

SIZE:

The Poriferas range in size from fewer millimeter wide to more than one meter tall.They be macroscopic i.e., can be seen with naked eye.Scolymastra joubini-a barrel same glass sponge of Antarctica is more than a metre tall.

COMPOSITION:

These animals are composed of many cells,however,there is no tissue organization and create no organs.Sponges lack symmetry.

In most sponges,the body wall is organise of :

(1)an outer layer,pinacoderm,made up of cells called pinacocytes and,

(2)an inner layer,choanoderm,made of flagellated collar cells called choanocytes.

Between these twain layers is present gelatinous

mesenchyme which may contain amoeboid cells and spicules or sponginfibres.

Penetrating the pinacoderm are cylinderical cells called sporocytes.

BODY CAVITY:

There is a single cavity inside the body,the

spongocoel.In most sponges, this spongocoel may be divided into flagellated chambers or canals,lined by flagellated choanocytes.

CIRCULATION AND RESPIRATION:

Numerous pores are present in the body wall.



The pores through which water enters the body are called ostia and pore through which the water leaves the body is known as osculum(main opening).There are no respiratory or circulatory organs.

NUTRITION:

Since the sponges are sessile,therefore,these depend

upon the intellectual nourishment coming to them along with water currents brought about by driving force of flagella of choanocytes.The viands includes small animals called zooplankton and plants called phytoplankton which constitute about 20% of thier food.

80%of thier food consists of detrital organic particles.The food enters the spongocoel cavity through ostia.The food is ingested by the flagellated cells,the choanocytes.The waste products either...

If you want to get a sufficient essay, order it on our website: Orderessay



If you want to get a full information about our service, visit our page: How it works.