The word Porifera is derived from the Latin word porous meaning pore and ferro meaning. They are called spore-bearing animals. The animals of this phase are known as sponges. Animals of this phase are called living pumps. The number of species in this category is about 8,659. Robert Grant (1836) named this group Porifera.
Characteristics of the circulation phase
1. They are the simplest multicellular organisms and are immobile.
2. Their body wall has numerous openings called ostia.
3. The body contains flagellated cells called koanocytes.
4. The body has a cavity called spongocele or paragastric. Each spongocele has a single pore called an osculum.
5. The body does not have well-organized organs, organs or systems.
6. They have a duct system in their body. There are three types of canal system. Ascon type, cycon type and leucon type. It functions in respiration and water flow.
7. Endoskeleton composed of spicules or spongy fibers. Spicules are composed of lime and spongy collagen proteins.
8. The body wall consists of 3 layers. Pinoderm on the outside, mesenchyme in the middle and choanoderm on the inside.
9. The matrix in the middle of the body wall contains a gelatinous protein called mesohyl. This matrix contains amoebocytes and skeletal material.
9. Food, oxygen, and sperm enter the ostia through water currents.
10. They are bisexual and reproduce both sexually and asexually. Asexual reproduction occurs by buds or gameules.
11. The life cycle consists of amphiblastula or parenchymula larvae.
Classification of Porifera
The order Porifera is divided into 3 classes.
1. Calcarea: They are small in size and pale in color. Spongin is less. Their skeleton is made of calcium carbonate. They are quite fragile in nature. For example – Sycon gelatinosum.
2. Hexactinellida: These are cup or vase shaped sponges. Large in size. Their spicules are made of silica. Exopinacoderm absent. For example – Euplectella aspergillus.
3 Demosponges: They look like cups or vases and are large. Their choanocytes are narrow. Spicules are made of silica. For example – Spongilla locustris.
Animals of the order Porifera
Scypha gelatinosum
Spongilla – Spongilla lacustris
Bath sponge – Spongilla officinalis
Freshwater sponge – Spongilla proliferan
Clathrina – Clathrina lacunosa
Leucosolenia – Leucosolenia complicata
Euplectella – Euplectella aspergillus
Chalina – Chalina oculata
Hyalonema – Hyalonema longissimum
Euspongia – Euspongia officinalis
Chiona – Chiona celata
Grantia-Grantia compressa
Neptune Cup – Poterion neptuni
Ostia
Ostia means hole. Ostia are the tiny openings on the outside of the body of peripheric animals. Water enters the body through the ostia. For example – Scypha (Scypha gelatinosum).
spongocoel
A spongocele is called a paragastric cavity. The body cavity of peripheric animals is called spongocele. The opening of spongocele is called osculum. The spongiocele holds water and exits the body through the osculum. For example – Spongilla (Spongilla lacustris).
Choanocyte
Cells with goblet-shaped flagella in the bodies of protozoa are called choanocytes. It resides within the walls of the ducts. It controls the flow of water.
Spicule
The tiny spines that make up the body structure of animals of the peripheries phase are called spicules. It is composed of lime or silica. It is a hard material. Neptune Cup (Poterion neptuni).