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Sponges, Cnidarians and Platyhelminthes
BIOL 1407
Invertebrates
• Animals without backbones
• Most animals
Sponges
• Porifera ≠ clade• Two possible
phyla:– Silicea (most
sponges)– Calcarea
• Photo Credit: BIOL 1407 Student
Characteristics of Sponges
• Cellular organization• Radial or no
symmetry• Photo Credit: BIOL 1407 Student
Characteristics of Sponges
• Filter feeders• Aquatic• Sessile• Photo Credit: Mila Zinkova, 2008,
Wikimedia Commons
Cell Types
• Choanocytes• Amoebocytes• Epidermal cells• Porocytes (in
some)
Choanoflagellates and Choanocytes
Skeleton
• Spicules– Calcium carbonate– Silica
• Spongin– Collagen protein
• Photo Credit for bath sponges: Alcinoe, 2005, Wikimedia Commons
• Photo Credit for Venus’ Flower Basket: NOAA, 2002
Phylum Cnidaria
• Hydroids (Hydra, Obelia)– http://www.youtube.com/watch?v=12OmszObAkM&feature=related
• Corals and Sea Anemones
• Jellies
• Cubozoans (sea wasps)
Hydroids
Photo Credit for Portuguese Man o’ War: UNK Vieques 2008 Field Trip
Corals and Sea Anemones
Photo Credit for Hard Coral: BIOL 1407 Student
Jellies and Cubozoans
Characteristics of Cnidarians
• Radial symmetry• Diploblastic
– Epidermis– Gastrodermis– Mesoglea
• Gastrovascular Cavity• Tentacles with
cnidocytes
Two Body Forms
Exchange Processes
• Body wall Two layers of cells
• Cell transport occurs at both layers– Water Balance– Ion Balance– Waste Disposal– Gas Exchange
Digestion• Two forms
– Intracellular– Extracellular
• Extracellular digestion major evolutionary advance
• Allows animals to eat things larger than their cells
• Video: http://www.youtube.com/watch?v=M3VSvyxrwXA
Intracellular vs. Extracellular Digestion
Transport
• As cnidarian moves, water moves through GVC
• GVC serves as transport system
• Video: http://www.youtube.com/watch?v=oCJwHogXtKE&eurl=http://video.aol.com/video-detail/jellyfish-swimming-monterey-bay-aquarium/1285587528
Platyhelminthes
• Free-living Flatworms– Planarians– Marine Flatworms
• Flukes
• Tapeworms
Planarian and Marine Flatworm
Photo Credit of planarian: Dr. Stephen Bostic, 2008
Fluke
Tapeworm
Characteristics of Platyhelminths
• Bilateral Symmetry• Triploblastic• Acoelomate• Gastrovascular
Cavity– Extensive branching
• Flat body• Photo Credit: Richard Ling, 2005, Flickr
Exchange Processes• Body is flat and thin
↑ Surface Area• Highly branched GVC
↑ Surface Area• Cell transport occurs
at both places– Water Balance– Ion Balance– Waste Disposal– Gas Exchange
Photo Credit of planarian: Dr. Stephen Bostic, 2008
Transport
• GVC serves as transport system
• Video: http://www.youtube.com/watch?v=A6N8KZqGAJg&feature=related
• Photo Credit: Richard Ling, 2006, Flickr
Excretory System: Protonephridia
Centralized Nervous System
The End
Unless otherwise specified, all images in this presentation came from:
Campbell, et al. 2008. Biology, 8th ed. Pearson Benjamin Cummings.