Phylum Porifera

• Sponges are the simplest of all animals; best described as aggregations of specialized cells

• Sponges do not have true tissues or organs; cells are largely independent of one another

• All are sessile (non-mobile)• Porifera means “pore bearer”• NO body symmetry

Phylum Porifera

• Tiny pores, or ostia allow water to enter and circulate through a series of canals where plankton and other organic debris are filtered out and eaten

• Sponges are suspension feeders, animals that eat food particles suspended in the water column

• Filter feeders; they actively filter out food particles

Phylum Porifera

• Water is pumped into a feeding chamber lined with collar cells, or choanocytes

• Choanocytes have a flagella that generates a current, and a thin collar that traps food particles

• Food is then ingested within the cell

Phylum Porifera

• As sponges get larger, they need structural support

• Most have spicules, supporting structures of different shapes and sizes, made of silica or calcium carbonate

• Many also have a ‘skeleton’ of tough, elastic fibers made of a protein called spongin

Phylum Porifera

• Wandering cells, or amebocytes secrete the spicules and spongin

• Amebocytes also transport and store excess food particles, and can change into other cell types, quickly ‘repairing’ any damage to the sponge

• ~80% of food particles are engulfed and ingested by choanocytes; smaller particles, inc. bacteria and dinoflagellates are eaten by amebocytes

You are what you eat…

• The silica frustules of diatoms and other phytoplankton help make the glass spicules of sponges!

DiatomsSponge

Sponges are boring!

• A family of sponges known as boring sponges bore into shells by use of an enzyme produced by the amebocytes

• Sponge larvae settle onto wood and/or shells and create burrows where they will grow

Sponge worthy?

• Unlike most animals, many sponges reproduce asexually

• Branches or buds break off to form separate, but identical, sponges

• Like all animals, however, sponges also reproduce sexually– Specialized coanocytes or amebocytes produce

eggs and sperm– Sponge larvae is planktonic!