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Download Section 2: Energy Flow in Ecosystems
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Simple Invertebrates Phylum Porifera Pore – bearers : Sponges Section 1 Simple Invertebrates Section 1 Characteristics of Sponges • Most sponges are a mass of cells stuck together by a gel-like substance. • Sponges are classified as animals because – – – – multicellular heterotrophic have no cell walls some specialized cells Simple Invertebrates Section 1 Characteristics of Sponges, continued • A sponge’s body is a sessile, filter-feeding structure. • Water enters the sponge through ostia in the body wall and exits through the osculum. Simple Invertebrates Section 1 Characteristics of Sponges, continued • Lining the inside of a sponge is a layer of cells called choanocytes, or collar cells. – Trap material on their flagella – like extensions • Amoebocytes – move around the body wall collecting nutrients and carry away wastes Simple Invertebrates Section 1 Visual Concept: Feeding Habits of Sponges Simple Invertebrates Sponge Reproduction • Sponges reproduce both asexually and sexually. • Most sponges are hermaphrodites, – they produce both eggs and sperm – advantages? Section 1 Simple Invertebrates Section 1 Sponge Reproduction, continued • Asexually – Fragmentation – Budding • Freshwater produce gemmules, fluid – filled ball of ameobocytes • Sexually – External into water – Larva is mobile Simple Invertebrates Section 1 Groups of Sponges • Sponges live in warm, shallow sea water and in deep, cold areas of the ocean. A few species even live in fresh water. • There are three main types of modern sponges comprising the 5,000 species living today. • All have skeletons which keep the sponge from collapsing in on itself. Simple Invertebrates Section 1 Groups of Sponges, continued • The skeleton of most sponges is comprised of tiny needles made of silica or calcium called spicules. • A few sponges have a skeleton composed of a resilient, flexible protein fiber called spongin. • Modern sponges are classified according to the composition of the skeleton in their body wall. • Calcareous sponges have a hard skeleton while glass sponges have a latticelike skeleton. Simple Invertebrates Section 1 Summary • Sponges are classified as animals because they are multicellular, are heterotrophic, have no cell walls, and contain some specialized cells. • Sponges reproduce both asexually and sexually. Most sponges are hermaphrodites, which means they produce both egg and sperm. • The modern sponges are classified according to the composition of the skeleton in their body wall.
