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Phylum Porifera : Sponges. Biology 11. Characteristics. Name means “pore bearers”- body has many pores in it Sessile Multicellular Mostly marine (only 100/9000 are freshwater). Structure. Asymmetrical body shape Made of 2 cells layers Ectoderm Endoderm - PowerPoint PPT Presentation
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Phylum Porifera: Sponges
Biology 11
Name means “pore bearers”- body has many pores in it
Sessile
Multicellular
Mostly marine (only 100/9000 are freshwater)
Characteristics
Asymmetrical body shape
Made of 2 cells layers◦ Ectoderm◦ Endoderm
No specialized tissue or organ systems◦ Individual cells sense and react to environmental
changes
Structure
Do have specialized cells that fulfill the sponge’s life functions
◦Epidermal cells◦Pore cells◦Collar cells◦Amoebocytes
Specialized Cells
Epidermal cells form outer covering
Water is drawn in through pore cells into a central cavity
The collar cells have flagella that beat to create a current to make sure water is being drawn in through pore cells
Water flows out of sponges through a larger opening called the osculum
Make spicules◦Needle-like structures that provide
structural support◦Made of silica or calcium carbonate◦Some made of spongin protein (softer
skeleton) Carry nutrients to other cells Aid in reproduction
Amoebocytes
Contain a flagellum to move water in
Brings oxygen and food particles into body of sponge
Collar Cell
Water acts as the circulatory, respiratory, reproductive, and excretory systems
Brings in food, oxygen, carries away waste, gametes, larvae
Oxygen is brought in and carbon dioxide and other metabolic wastes are given off
Movement of Water
Feeding and Digestion◦ No mouth or digestive tract
◦ Are filter feeders- sift food particles from the water Driven by water flow Filtered by collar cells
Excretion◦ Driven by water flow
Life Functions
Respiration◦Oxygen diffused from surrounding water
into cells◦Carbon dioxide diffused from cells to
surrounding water
Movement◦Adults sessile: Remain attached, don’t move
◦Larvae are mobile
Sexual
Most are hermaphrodites (produce both egg and sperm)
Reproduction
Sperm released out of osculum and swim to another sponge (with the help of currents)◦Enter another sponge’s pore cell◦Picked up by collar cells◦Carried to an egg by amoebocytes◦Fertilization occurs◦Zygote develops into a flagellated larvae
which is mobile (can be dispersed)
Increase change of fertilization
They do not fertilize their own eggs with their own sperm
Why do sessile animals tend to be hermaphroditic?
Can also reproduce asexually by:◦Fragmentation: part of sponge breaks off◦Budding: mitotic growth and break off◦Gemmules: collection of cells that are
enclosed by hard outer covering contain spicules Form when conditions are unfavourable
Provides habitat for many other animals◦ Like snails, shrimp, sea stars, bacteria…
Is a food source for other animals
Provides a symbiotic relationships with bacteria (bacteria provide food and oxygen to sponge and remove wastes)
Ecological Importance
Used as bath sponges
Produce chemicals (to discourage other animals from eating them) that are being used in research for cancer, viruses, and antibiotics
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