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=oCJ
wHogXtKE&eurl=http://video.aol.com/v
ideo-detail/jellyfish-swimmingmonterey-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/watc
h?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.