Phylum Porifera Sponges Kingdom Animalia Phylum Porifera Classes

Phylum Porifera “Sponges” Kingdom: Animalia Phylum: Porifera Classes: Hexactinellida Demospongia Calcarea

Phylum Porifera • • Pronounced (po-rif'-er-a) The name means “bearing pores” 5, 000 living species Most primitive of all animals

Phylum Porifera Sponges are sessile, meaning they have a stationary, inactive lifestyle can move up to 4 mm per day Because they are sessile, they are highly dependent on ocean currents to bring food to them and eliminate waste products. Embryos are free-swimming.

Major Characteristics: They have no organs or true tissues. Digestion, respiration, and excretion all occur by simple diffusion directly into and out of the cells. No nervous system. Most sponges are asymmetrical. Occasionally radial

Major Characteristics: Their bodies are made up of thousands of cells mixed together in a gel-like mixture, supported by small skeletal structures called spicules.

Major Characteristics: • Feed by filtering water through their outer walls and pumping it out of body • Flow of water is uni-directional Sponges are made up of a system of tiny pores and canals that make up a intricate filter feeding system.

Structure/General Anatomy: • Opening at top called • • the osculum Gelatinous interior called the mesohyl The interior cavity called the spongocoel OSCULUM - opening SPONGOCOEL MESOHYL

Sponge Skeletons Thin strands of collagen are found throughout the bodies of sponges. The class of Demospongiae produces a form of collagen known as spongin.

Sponge Skeleton Spicules on the left Spongin on the right

Spicules:

Structure / Anatomy:

Structure / Anatomy: • No tissues or organs • Each type of sponge • cell is responsible for a specific function The outer surface is covered by tiny openings called ostia

Cellular Structure of Sponges The inner material that makes up the main body (a type of connective tissue) of a sponge consists of a loose gel-like mixture called Mesohyl. Porocytes make up the ostia that allow the passage of water into the sponge.

The epithelial cells of sponges are called Pinacocytes. These cells play a role in trapping food particles.

Amoebocytes are cells in the mesohyl that perform a variety of functions. The primary functions are digestion (archaeocytes) and production of spicules and collagen.

• The spongocoel is lined with flagellated cells called choanocytes or collar cells. • The flagella beat to cause a current – drawing water in through the ostia • The collar traps food particles

Cellular Structure of a Sponge

Structure / Anatomy:

Feeding: Moving Water/Current = Low Pressure • Flow of water through the • sponge allows for feeding, waste removal, and the intake of oxygen Sponges filter bacteria as a food source Some sponges filter as much as 1500 liters/day (that is equivalent to about 400 gallons/day). Water pumped in through the walls

Sponge Digestion

Digestive: • Filter feeders • NO GVC – food • • is digested intracellularly Collar cells engulf and digest food vacuoles Use amoeboid cells to distribute nutrients

Circulatory: • Amoeboid Cells in the wall transport food and nutrients

Excretory: • All wastes are purged through the main pore called the osculum

Respiratory • Various cells take in oxygen through diffusion

Sponge Sexual Reproduction Most sponges are monoecious. Meaning a single sponge can have both male and female sex cells. Sperm cells develop from choanocytes. Egg cells can develop from choanocytes in some species and from archaeocytes in others. After fertilization, the a free-swimming flagellated larva called a parenchymula breaks off from the adult sponge and are carried away by ocean currents.

Sponge Asexual Reproduction fragmentation and by external budding. Fragmentation occurs when a fragment is broken off from the main body of the sponge. Budding occurs when a small sponge grows off of the adult sponge. Eventually these can break off and regenerate.

Sponge Asexual Reproduction Gemmules are internal buds that usually remain dormant and contain archaeocytes. Gemmules are usually formed during unfavorable conditions After the unfavorable conditions pass, the archaeocytes can then be released - regenerate into a new adult sponge.

Parenchymula and Gemmules on the left Parenchymula on the right.

Sponge Ecology Adults are always attached to other objects. (rocks, corals, submerged objects etc. ) Many other organisms such as crab and fish live symbiotically in or on sponges. Some sponges live on other organisms like mollusk shells and corals.

Class Calcarea Spicules made of calcium carbonate (calcite and limestone) All three types of canals represented (asconoid, syconoid, and leuconoid). All marine Example (Clathrina)

Class Hexactinellida Six-rayed spicules made of silica (same substance as glass) Body often cylindrical and funnel shaped Syconoid or leuconoid All Marine Example, Venus Flower Basket (Euplectella)

Class Demospongiae Skeleton made of silica spicules that are not six-rayed, or a skeleton made of spongin, or both. Leuconoid type canal systems only. One family freshwater, all others are marine. Very diverse group of sponges