Poriferans (sponges)

• ‘pore bearing’• Spongocoel• Choanocytes or Collar cells• Archeocytes• Epidermal cells• Has Mesophyl sandwiched between two thin layers

of cells.

Defining Characteristics

• Microvillar collars surround flagella, with units arising from either single cells or syncytia.

• Lack nerves and no true musculature.

Skeleton• Sponges are either radially symmetrical or

asymmetrical.

• Mesohyl=Endoskeleton • Spicules=Sclerocytes• Spongin=Spongocytes

Food Capture and Digestion

• detritus particles, plankton, bacteria

• Choanocytes

• Food items are taken into individual cells by phagocytosis, and digestion occurs within individual cells.

Excretion and Water Balance

• A sponge has carbon dioxide and other wastes removed as the water moves in and out through the pores.

Respiration and internal Transport

• Diffusion of gases through the help of water

• Archeocytes remove mineral particles that threaten to block the ostia.

Nervous System

• A sponge has a very low level reaction to the world around it and does not have a brain per se.

Reproductive system

• Asexual+fragmentation+buds

*external buds*internal buds or gemmules

• Sexual (mesohyl)+eggs and sperms+hermaphroditic

*External and internal fertilization

Development

• Hollow blastula or Coeloblastula

• Amphiblastula-the hollow sponge larvae

• Some species, from coeloblastula to stereoblastula

• Larvae are incapable to feeding and swim for less than 24 hours before metamorphosing.

Ecology and Evolution

• 98% in marine

• 2% in water and mostly with spongin fiber

• Many in tropics

• Sponges have strong structures that are able to handle the high volume of water that flows through them each day

• release toxic substances into the environment

PLACOZOANS (Flat plate)

• They were discovered in the late 1880's living on the glass walls of an aquarium in a European laboratory.

• Single species

Defining Characteristic

• Multicellular• Amorphous• Mobile• flagellated animals lacking a body cavity, digestive

system and nervous system • composed of 2 layers of epithelial cells.

• 2 distinct layers of epithelial cells +ventral- columnar cells w/ flagellum

- Glandular cells with enzymes - Endodermal

+Dorsal- Flat, thinner and No gland cells. -Ectodermal

+In between- fluid-Contractile fibrous cells.

Movement

2 Ways;

• gliding on their cilia

• changing their shape like an amoeba.

Digestion

• Atops the food using the Ventral surface • No sign of phagocytosis• Extracellular digestion

Reproduction

• Sexual

+ generally, produces one oocyte.

+developed embryos

• Asexual

+Budding

+Fragmentation

+Binary fission