Phylum Porifera The Sponge

Sponges are Simple, multicellular animal with pores Asymmetrical, no organs or tissues Invertebrates (lacking backbone) without any specialized features Aquatic (mostly marine) Sac-like bodies with many pores Sessile (no movement)

Classification: Domain- Eukaryota Kingdom - Animalia Phylum - Porifera Based on spicules (tiny needle-shaped structure that form the skeleton of the sponge) Domain- Eukaryota Kingdom - Animalia Phylum - Porifera Class - Hydrozoa -Scyphozoa -Anthozoa

Anatomy of Porifera Epidermal Cells (outer layer of cells) Mesoglea (middle layer that contains spicules) Spicultes form the skeleton Collar cells (Choanocytes) No Nerve Cells

3 Types of Cells Pinacocytes: flat cells that cover the outer surface of sponges. -Function: Protect sponge’s surface Provide limited movement Amoebocytes: Cells that move through a jelly-like layer secreting the spicules and spongin Choanocytes: cells that create a current to bring in water Function: Engulf and digest food particles

Spicules- Forms the skeleton 3 Types Calcium Carbonate (chalk) Silica (glass) Spongin (protein made of collagen) gives the sponge flexibility

Sponge Anatomy Draw and label a choanocyte (collar cells) in your notes

Pinacocytes These cells are the "skin cells" of sponges. They line the exterior of the sponge body wall. They are thin, leathery and tightly packed together. Porocytes Poriferans do not have any muscle cells, so their movement is rather limited. However, some poriferan cells can contract in a similar fashion as muscle cells. Porocytes which surround canal openings and pores can contract to regulate flow through the sponge. Sponge Cell Wall

Diet of Porifera Sessile filter feeders Remains in one place and filter food from the water Collar Cells engulf and digest food particles in the cells.

TYPICAL SPONGE FEEDING Water flowing through sponges provides food and oxygen, as well as a means for waste removal. This flow is actively generated by the beating of flagella. This moving water creates an area of low pressure above the 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 24 hour period. Some sponges trap roughly 90 percent of all bacteria in the water they filter.

Compare and Contrast the 3 sponge body types Use these diagram to label the water flow of water and nutrients Complete the venn diagram to discuss the similarities and differences between the 3 types of sponges

Reproduction of Porifera Regeneration (ability to replace lost body parts) Asexually Budding Fragmentation Sexually (egg and sperm) hermaphroditic Budding

Asexual Reproduction aka monoecious or hermaphroditic 3 Types: Budding Fragmentation Gemmule Formation (internal buds – usually in freshwater )

Asexual Reproduction:Gemmules Asexual Reproduction where An internal bud, found in some freshwater sponges and designed to overwinter in cold climates and grow to a new sponge in the spring. Environmentally resistant because it is lined with spicules. They open when conditions are suitable, releasing the cells within so they can grow, divide, differentiate, and organize, forming new sponge.

Asexual Reproduction: Regeneration Definition: Ability to replace lost body parts A piece cut from the body of a sponge is capable of growing into a complete sponge. If a sponge is cut into small pieces and squeezed through a fine silken mesh to separate cells, the separated amoebocytes will reunite and in a few days will develop canals, flagellated chambers and skeleton and grow up into a new sponge. This power of regeneration helps the sponges to repair the damage caused in the harsh environment.

Asexual Reproduction: Fragmentation Sponges can break into several pieces along several lines of weakness and breaking into fragments that are capable to tide over unfavourable environmental conditions and grow into complete sponges in the following favorable season.

Sponge Sexual Reproduction The process of sexual reproduction between sea sponges occurs in the mesohyl, an gel layer that is the innermost layer of the sponges body. After developing gametes, the "male" sponge will release its sperm into its canals. The sperm is pumped out of the sponge and into the surrounding water by the osculum. Once in the water the sperm cells are then taken into the pore systems of neighbour "female" sponges similarly to how food particles would be. Once inside a female sponge the gametes are collected by collar cells. These cells, also known as choanocytes, then proceed to shed their collars. In the majority of sea sponges, the fertilized egg will then develop into a blastula. In some species the blastula will be released into the water directly after fertilization, where in others release is delayed and some development will first take place within the parent sponge. Upon release, the larvae may either settle immediately and grow into an adult sponge, or may act planktonically for a few days. The next time the sponges reproduce, they may change sexual roles.

Sponges are usually grouped according to the type of spicules into three classes: Class 1: Calcarea about 700 species sponges with spicules of calcium carbonate, needle-shaped or three-rayed or four-rayed canal systems: asconoid, syconoid, or leuconoid and all marine examples: Sycon, Leucosolenia

Class 2: Class Hexactinellida about 500 species sponges with three-dimensional, spicules spicules often united to form network body often cylindrical or funnel-shaped canal systems: syconoid or leuconoid all marine, mostly deep water Examples: Euplectella (Venus' flower basket), Hyalonema. Hyalonema Euplectella (Venus’ flower basket)

Class 3: Demospongia about 7000 species sponges with siliceous spicules (not six-rayed), spongin, or both canal system: leuconoid one family freshwater, all others marine examples: Spongilla (freshwater sponge), Spongia, (commercial bath sponge), Cliona (a boring sponge) most sponges belong to this class Cliona Spongia

Class 4: Sclerospongiae Coral sponges & have spongin & silica and calcium carbonate spicules This is a small group of sponges that resemble corals. All in this class have the leuconoid canal system. All Marine, usually found in dark tunnels in coral reefs Fossil Cup Sponge

Sponge development-Indirect or Direct? Direct development refers to the process of development in which an animal is born in a smaller version of its adult form. There is no major transition in the form of the animal from infancy to maturity. With indirect development, an animal's birth form is very different from the adult form. The embryo hatches from the egg in a larval form (amphiblastula). The larva undergoes a drastic metamorphosis in order to achieve its adult stage. Animals that undergo indirect development lay numerous eggs.

Indirect or Direct? Indirect development due to the free swimming sedentary(using cilia to move) larval stages and sessile adults

Diagram Labelling: Asexual Reproduction Spongocoel: internal cavity that opens to the outside by an osculum Porocytes: small pores in epithelia wall to all oxygen and food to enter. Osculum: large opening where water is expelled.

Bonus: Many years ago, scientists considered sponges to belong to Kingdom Plantae. What sort of evidence convinced them that sponges belonged to Kingdom Animalia? ON YOUR TEST!