BIO SCI 100 1st Edition Lecture 6Outline of Last Lecture I. ProtozoaII. Cellular OrganellesIII. Protozoan DiversityIV. Plasmodium Life CycleOutline of Current Lecture I. EvolutionII. Grouping PoriferansIII. Phylum Porifera: DiversityIV. Phylum Porifera: EcologyCurrent LecturePhylum PoriferaI. Evolution- Ancient group, fossils from the early Cambrian period 600 mya.- Metazoan animals.- Porifera means “pore-bearing”.- Once thought to be plants.- Mobile as larvae, but sedentary as adults.- Simplest metazoans.- Aggregation of cells.o No true tissues or organs.- An aggregation of cells and spicules in a gelatinous matrix.- Sponge rigidity is due to spicules composed of calcium carbonate or silicone.- Metazoan advantage:Higher cell surface: volume ratio.- Increased area available for metabolic activities.- Ostia (pores) and canals create filter-feeding system.- Water currents bring food and oxygen in and remove wastes.These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.- Mostly marine environments.II. Grouping PoriferansCanal Complexity1. Asconoid; flagellated spongocoel.2. Syconoid; canals folded in layers andlined with flagella.3. Leuconoid; chambers lined with flagellamost efficient in moving waterand extracting nutrients.Water Flow- Water flow through a sponge is very important to survival!o Brings in food and oxygen and allows wastes to flow out of sponge.o Water volume can be 20,000 times body volume per day!o Controlled by flagella.- Water flow is unidirectional.o Water drawn in through the pores called ostia.o Water out through the osculum.Feeding & Digestion- How do sponges feed?o Filter feeding.o Filter tiny food particles out of water: bacteria &plankton.- Cells involved in feeding & digestion:• Choanocytes: line canal system.• Flagellated cells that trap food particles using sieve-like collar.• Pass food particles to archaeocytesfor digestion by phagocytosis.Reproduction- All sponges are capable of both asexual and sexual reproduction.- Asexual reproduction by budding: external &internal.- Common in poor environmental conditions.Sexual Reproduction- Sponges are monoecious:produce both male &female gametes.- Sperm are released into the water via canal systemo These sperm are taken in from the water by other sponges through their canal system; o Then sperm migrate to the eggso Fertilized eggs develop into larvae, that are released into water via canal system- Larvae have cilia and are mobile (disperse) before settling on the ocean floor to develop.III. Phylum Porifera: Diversity- Class Calcarea: Sponges with spicules of calcium carbonate.o Very small (less than < 10 cm tall).o Usually tubular.o Spicules straight or with 1-4 branches.o Most primitive Class of sponges.o Shallow marine habitats.- Class Hexactinellida: “Glass sponges” that are made only of silicone.o Spicules have six points.o Most rigid of all sponges.o 10-30 cm or larger in height.o All marine, mostly deep seaforms.o Found worldwide, but most abundant in the Antarctic.- Class Demospongiae: skeleton of silicone, spongin fibersor both.o Includes 80% of all sponge species.o Can be a few millimeters to over 2 meterstall.o Leuconoidcanal system.o Mostly marine species :shallow & deep water.o Includes the “bath sponges”.IV. Phylum Porifera: Ecology - 5,000 + species worldwide.o Mostly shallow seas, but present at all depths.o Make important shelter for many other marine animals.o Some live in mutualistic symbiosis with algae.o Bio-indicators of pollution.o Important food source for Hawksbill turtles.- Sponge Predatorso Not eaten by many animals.o How does a sessile organism avoid predation? Presence of spicules. Evolved chemical defenses. Produce toxins that smell or taste bad to predators.- Focus of research for new drugs to fight human diseases such as AIDS, TB, & Cystic