Phylum Porifera General Characteristics SPONGES Simplest of all

Phylum Porifera

General Characteristics �SPONGES! �Simplest of all animals �Cellular level organization �Specialized cells, but no tissues (bodies are a loose aggregation of cells) �No true tissues or organs �Radial or asymmetrical �Marine and Freshwater �Saltwater are colorful �Freshwater are dull green color

General Characteristics Cont. • Sponges are sessile (not free moving) as adults • Free swimming larval stage called dipleurula • Porifera means pore-bearing • Water enters through pores (ostia) bringing in food and oxygen • Sexual & Asexual Reproduction • Osculum- large opening at the top where excess water leaves

WATER OUT Water Flow Through the Sponge WATER IN Osculum

3 Basic Cell Types 1. Pinacocytes 2. Mesenchyme Cells 3. Choanocytes

3 Basic Cell Types • 1. Pinacocytes- flat cells that line the outer surface of the sponge. –May be slightly contractile –Porocyte: a specialized type of pinacocyte; are tube-like in shape; contractile; and can regulate water circulation.

� 2. Mesenchyme Cells- move around in the mesohyl layer; are specialized for reproduction, secreting the skeleton, transporting/storing food. �Amoebocyte: jelly-like layer just underneath the pinacocyte layer. (makes spicules – skeletal)

• 3. Choanocytes- flagellated cells that line the inner chamber of the sponge; called collar cells. –Flagellum: flagella spins to create water currents to pull in water and food –Collar: “trap” plankton and other fine particles from the water

Choanocyte

Structural Skeleton �Consists of either one or all of the following: �Spicule: microscopic needle-like spikes that are made of Calcium carbonate (Ca. CO 3) or silica (glass). �Spongin: a fibrous protein made of collagen

Sponge Skeletons Silica Spicules Limestone Spicules SPONGIN

Sponge Body Types • 3 Kinds–Ascon – Sycon –Leucon

Ascon • Simple tube perforated by pores • Open internal part of tube is called the spongocoel (coel = gut) • Are vase-like • Least common type of sponge • Single opening to the outside called the osculum

Sycon • Sponge wall is folded into canals • Choanocytes line the radial canals to move water osculum

Leucon • Have an extensively branched canal system. • Multiple canals lined with flagellated cells • Multiple ostia for water to exit • Increased surface area means more water can move through sponge

Body Forms Summary

Reproduction �Sexual Reproduction- sponges are monoecious (male and female in the same body) �Release sperm and eggs into the water from the Osculum �Cross-Fertilization takes place in the ocean Fertilized eggs form larvae which swim off looking for a place to settle

Reproduction Sponge Releasing Eggs & Sperm

Reproduction Cont’ o Sponges can regenerate (regrow) lost body parts through mitotic cell division (asexual) o Sponges also reproduce asexually by (budding)

Reproduction Cont’d gemmule �Asexual Reproduction- involves the formation of gemmules �gemmules: resistant capsules that sponges release to survive unfavorable conditions. When conditions become favorable, the gemmules sprout into sponges.

CLASSES • Phylum Porifera – 3 Classes • Class Calcarea • Class Hexactinellida • Class Demospongiae

Class Calcarea • • Spicules made of Calcium Carbonate Can have all three body forms Most primative Ex. Grantia

Class Hexactinellida • Deep sea sponges • Can have syncon or leucon body forms –Often fused into an intricate lattice –Glass sponges (silica)

Class Demospongiae • • Spicules made of silica, spongin, or both. Most common (fresh (green) & salt) All are Leuconoid Ex: bath sponge