Phylum Porifera Pore – bearers : Sponges
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
Characteristics of Sponges, continued • A sponge’s body is a sessile, filter-feeding structure. • Water enters the sponge through ostiain the body wall and exits through the osculum.
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
Sponge Reproduction • Sponges reproduce both asexually and sexually. • Most sponges are hermaphrodites, • they produce both eggs and sperm • advantages?
Sponge Reproduction, continued • Asexually • Fragmentation • Budding • Freshwater produce gemmules, fluid – filled ball of ameobocytes • Sexually • External into water • Larva is mobile
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.
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.
Classification Phylum Porifera • Class Calcarea (Calcium) • Class Hexactinellida (Silica) • Class Demospongia (Spongin)
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.