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.