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Phylum Porifera : Sponges

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

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Phylum Porifera : Sponges

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  1. Phylum Porifera: Sponges Biology 11

  2. Characteristics • Name means “pore bearers”- body has many pores in it • Sessile • Multicellular • Mostly marine (only 100/9000 are freshwater)

  3. Structure • Asymmetrical body shape • Made of 2 cells layers • Ectoderm • Endoderm • No specialized tissue or organ systems • Individual cells sense and react to environmental changes

  4. Specialized Cells • Do have specialized cells that fulfill the sponge’s life functions • Epidermal cells • Pore cells • Collar cells • Amoebocytes

  5. Epidermal cells form outer covering • Water is drawn in through pore cells into a central cavity

  6. 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

  7. Amoebocytes • 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

  8. Collar Cell • Contain a flagellum to move water in • Brings oxygen and food particles into body of sponge

  9. Movement of Water • 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

  10. Life Functions • 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

  11. Respiration • Oxygen diffused from surrounding water into cells • Carbon dioxide diffused from cells to surrounding water

  12. Movement • Adults sessile: Remain attached, don’t move • Larvae are mobile

  13. Reproduction • Sexual • Most are hermaphrodites (produce both egg and sperm)

  14. Sperm released out of osculumand 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)

  15. Why do sessile animals tend to be hermaphroditic? • Increase change of fertilization • They do not fertilize their own eggs with their own sperm

  16. 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

  17. Ecological Importance • 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)

  18. 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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