Phylum Porifera Chapter 26

General Characteristics No mouth, gut, specialized tissues or organ systems Multicellular Kept rigid through deposits of calcium carbonate, silica or spongin Reproduce asexually through budding and/or sexually through sperm and egg Water enters through the central cavity, deposits nutrients, and leaves through a hole called the osculum (filter feed) sessile majority are marine (salt water) species, ranging from tidal zones to depths exceeding 8,800 metres

Gemmules When conditions deteriorate, for example when temperatures drop, many freshwater species and a few marine ones produce _______________, “survival pods,” of unspecialized cells that remain dormant until conditions improve and then either form completely new sponges or re-colonize the skeletons of their parents.

Ecological Importance Environmental >____________________________________ Economical >____________________________________ Medicinal >___________________________________ ____________________________________

Phylum Cnidaria

General Characteristics Have a mouth and gastrovascular cavity with digestive enzymes Lacks an _______________(excretory system) and _______________________ Simple nervous system (nerve nets and sensory cells – statocysts and ocelli) Soft bodied with stinging tentacles around their mouth Carnivores (capture prey with their nematocysts) Asexual reproduction: _________________ Sexual reproduction occurs in medusa form (depending on the species, fertilization is external – chance encounter or inside an egg-carrying medusa)

Two Body Forms 1. Polyp – sessile flowerlike 2. Medusa – motile bell-shaped Depending on the type of cnidarian, their life cycle may include both body types.

Three Classes of Cnidarians 1. ___________________ -size: few cm to a metre -freshwater -polyp and short medusa phase -usually separate sexes, but a few are hermaphroditic ex: hydras Portuguese Man-of-War

Three Classes of Cnidarians 2. ____________________ -medusa is large and long-lived -polyp is a tiny larval stage -can grow up 2m in diameter -most nematocysts are harmless to humans ex: Jellyfish

Three Classes of Cnidarians 3. _________________ -polyp stage only -many shallow water species depend on photosynthetic symbiotic relationships -can grow up to 1m ex: sea anemones and corals

Ecological Importance

Unsegmented Worms Phylum Platyhelminthes and Phylum Nematoda

General Characteristics _____________________ Simple nervous system with sensory organs and a simple brain in their anterior region (head) Has 3 germ layers (ectoderm, mesoderm and endoderm)

Phylum Platyhelminthes (Flatworms) -Carnivores that feed on tiny aquatic animals, scavengers feeding on recently deceased animals, or parasites feeding on blood or tissue fluids inside their hosts body -Use a pharynx to suck food into a gastrovascular cavity -Undigested food is expelled through the mouth (____________________________) -Lack a specialized circulatory and respiratory system. Depend on diffusion to transport oxygen and nutrients to their tissues and wastes out -Have light sensitive organs ( ____________________) Examples: >Class Turbellaria: __________________________ >Class Trematoda: __________________________ >Class Cestoda: ____________________________

Phylum Nematoda (Roundworms) Have a ____________ and an ______________ Simple nervous system Bilateral symmetry Free-living Mostly carnivorous Breathe and excrete their wastes through their body walls via diffusion Reproduce ___________

Ecological Importance Mostly negative – disease causing in humans and animals – Example: Trichinella, elephantiasis, Ascaris, etc. Your Task: read and make notes pages answer questions #1-5 pg 578