Phylum Porifera

PHYLUM PORIFERA SPONGES

Sponges • Pore-bearing animals • Most primitive of all animals. • Phylum Porifera is huge phylum that contains about 5000 species which lives in seas, lakes and rivers. • Most sponges are marine while some are fresh water species. • Sessile or non-moving. • Do not exhibit any symmetry. • They vary in color—from white, gray, brown to red, orange, yellow, purple, and black.

The freshwater sponge, Spongilla lacustris

Marine sponge, yellow tube sponge.

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DIFFERENT COLORS OF SPONGE

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• Sponges are all filter feeders. • Their body consist of tiny pores, the small incurrent pores & the large excurrent pores. • They do not have a nervous system. • They’re complex colonies of flagellated unicellular protozoalike organisms. • The only animal phylum that does not possess at least 2 distinct embryonic tissue layers. • Their unique lack of tissue organization has prompted taxonomists to classify them as parazoa (next to animals).

• Some sponges are specialized for reproductive or nutritional purposes, and this slight organizational complexity gives them a toehold on the edge of the animal kingdom. • Sponges include a system of pores (also called ostia) and canals, through which water passes. • They do not have any organ. • They often have a skeleton of spicules. • They also have a protein in their body called spongin which helps provide body support. • They have a hollow space inside.

Structure of a Sponge.

• Sponges are the simplest animals. They have no head, arms, legs or organs. Since they have no stomach and a digestive gut, sponges depend on a system of water canals in its body to bring in food and oxygen which also carries away waste and carbon dioxide. Sponges eat tiny plants and animals called plankton. To get the food, flagella circulate the water through the sponge. The water enters through the sponge's pores and flows through chambers called flagellated chambers.

The chambers are called this because each cell that lines them have a flagellum, a long thread that whips around to help the water flow. The water then moves out of the sponge's body through the osculum, a large opening in the sponge's body. The tiny animals and plants that are captured by the cells that line the chambers are called choanocytes or collar cells. Each of these cells holds a flagellum. The ameobacyte or amoeba-like cells digest the food, captured by the flagellum.

Water Circulation • The open pores on the surface of the sponge come in two types. The 'entry' cells are known as ostia, while the exit cells, which are bigger, are the oscula, often termed 'excurrent'. Specialised cells, the choanocytes, allow water into the ostia. • Water flows through the body of the sponge, entering at the ostia, circulating around the canals and chambers, then leaving from the oscula.The flow of water through the sponge is unidirectional, driven by the beating of flagella which line the surface of the chambers.

The water movement through some sponges is aided by ambient currents passing over raised 'excurrent' openings, the oscula. This moving water creates an area of low pressure above the excurrent openings that assists in drawing water out of the sponge. Sponges are capable of regulating the amount of flow through their bodies by the constriction of various openings. The volume of water passing through a sponge can be enormous, up to 20 000 times its volume in a single 24hour period.

Reproduction of Sponges 1. Asexual Reproduction is done through the formation of buds or gemmules. Buds are groups of cells that enlarge and attach to the parent for some time, while gemmules are groups of cell masses, which are surrounded by a heavy coat of organic matter and produced by the parent sponge — these are capable of growing into adult sponges.

2. Sexual Reproduction is done when these sponges develop eggs & sperms. Sperms shed into the water fertilize the egg in another sponge by passing through the incurrent pores. The fertilized egg develops into a flagellated larva that escapes from the sponge and grows into a young sponge after swimming for a while.

Sexual Reproduction of sponges

EXAMPLES OF SPONGES

Orange Puffball sponge (Tethya auranti)

Gray moon sponge (Spheciospongia confoederata)

Ball Sponge

Branching Tube Sponge (Pseudoceratina crassa)

Colony of Blue Haliclona Sponge

Baitfish Ball over a Barrel Sponge (Xestospongia testudinaria)

Giant Barrel Sponge (Xestospongia muta)

Economic Uses of Sponge • The remaining skeletal parts of the sea sponges are the ones that are used by humans. • Soft sponges are for padding for helmets, portable drinking utensils and municipal water filters. • Synthetic sponges, they were used as cleaning tools, applicators for paints and ceramic glazes and discreet contraceptives.

KITCHEN SPONGE for cleaning purposes.

For bathing

Applicators for paints

Contraceptives

Make flowerpots hold water longer

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