Porifera and Cnidaria Notes PDF

1 OUTLINE Phylum Porifera - Sponges 1. Introduction 2. Cell types 3. Canal systems 4. Reproduction 7 CELL TYPES General Arrangement of Cell Types in Sponge Body: Porocytes Archaeocytes (Ostium)...

1 OUTLINE Phylum Porifera - Sponges 1. Introduction 2. Cell types 3. Canal systems 4. Reproduction 7 CELL TYPES General Arrangement of Cell Types in Sponge Body: Porocytes Archaeocytes (Ostium) Pinacocytes (Pinacoderm) Mesohyl (gelatinous matrix) Sclerocytes Choanocytes (mineral (Choanoderm) spicules) 8 CANAL SYSTEMS Three major canal system types 1. Asconoids - flagellated spongocoels 8 CANAL SYSTEMS 1. Asconoids - flagellated spongocoels osculum - excurrent canal - one & large WATER ostium - incurrent canal - many & small - porocyte choanocyte - choanoderm pinacocytes - pinacoderm mesohyl spongocoel (Gelatinous matrix) 9 CANAL SYSTEMS 2. Syconoids Incurrent Canal - flagellated canals Ostium Prosopyle Choanocyte Canal (Radial Canal) Apopyle Spongocoel NOT lined with choanocytes 10 11 CANAL SYSTEMS 3. Leuconoids - flagellated chambers - most sponges are leuconoid - no spongocoel - usually have more than 1 osculum ostium 12 13 REPRODUCTION - All sponges reproduce asexually and sexually. Asexual Reproduction in Sponges: 1. Gemmules: - archaeocytes cluster together inside the sponge and phagocytose other cells to store nutrients. - Cells on outer perimeter secrete thick protective covering of spongin with microsclere (capsule). (micropyle) (capsule) (cluster of archeocytes) 14 REPRODUCTION Gemmule -When environmental conditions are favourable, archaeocytes leave gemmule through micropyle (opening in gemmule) and differentiate into new individual. (micropyle) (capsule) (cluster of archeocytes) 14 REPRODUCTION Gemmule -well developed system in freshwater sponges. -habitat prone to seasonal freezing and periodic dessication. -Gemmule withstands dessication, freezing temp., low oxygen. (micropyle) (capsule) (cluster of archeocytes) 15 REPRODUCTION Asexual Reproduction in Sponges: All sponges are capable of fragmentation and/or budding 2. Fragmentation 3. Budding 16 REPRODUCTION Sexual Reproduction in Sponges: - Elusive processes because no specific reproductive structures. 1. Viviparous sponges: (Usually Monoecious) - sperm formed from choanocytes (spermatocysts = special flagellated chamber) and released to the environment. - Eggs formed from archaeocytes (sometimes choanocytes), distributed throughout mesohyl. - Parenchymula : flagellated larvae 17 18 REPRODUCTION 2. Oviparous sponges: (Usually Dioecious) - release egg and sperm to the environment (usually a mass population event at one time of the year, ie: October/November at new moon). - fertilization and development all occur in the environment. - eggs with nurse cells snag sperm of other individuals and soon become negatively buoyant and sink. Male sponge: sperm release Female sponge: egg release 19 1 OUTLINE Phylum Cnidaria - Jellyfish, Sea anemones, Corals 1. Introduction 2. Body Forms and Structure 3. Cnidae (e.g.: nematocysts) 4. Nerve Net / Muscles 2 INTRODUCTION Chordates Arthropods Hemichordates Annelids Brachiopods Echinoderms Mollusks Bryozoans Nematodes Nemerteans Gastrotrichs Rotifers Flatworms Cnidarians ✓ Sponges Ancestral Metazoan ✓ Unicellular Eukaryotes 3 INTRODUCTION - polymorphic: 2 body forms (polyp, medusa) - 2 germ layers (ectoderm, endoderm) - radial symmetry - Gastrovascular cavity (enteron) with single opening, surrounded by tentacles - Cnidocytes (contain cnidae)