Lab Exercise 4 Porifera Cnidaria Platyhelminthes
Organization in Animals
• Cellular level: Random assembly of cells
• Tissue level: Cells connected to form distinct tissues
• Organ level: Tissues connected to form organs
Levels of Biological Organization
• Organ system level
– All more advanced organisms
– Multiple organ systems working together form an complex organism
1 Biological Symmetry
• Radial Symmetry
– Body can be divided into mirror image halves through the center
–Examples • Mature Cnidarians
Biological Symmetry
• Bilateral Symmetry
– Body is divisible into left and right halves by a single plane only
–Examples •Flatworms • Arthropods • Vertebrates
Biological Symmetry
• Asymmetry
– Body cannot be divided to produce mirror image halves
–Example • Porifera
2 Embryonic Development
Cell Cleavage
Blastula Gastrula
Gastrula
Gastrula Gastrula (Diploblastic) (Triploblastic) Ectoderm
Endoderm
Mesoderm
Archenteron- Space within endoderm
Blastopore Blastopore
Archenteron: becomes adult digestive tract Blastopore: becomes the mouth or anus
Phylum Porifera
• Diploblastic • Asymmetrical • No digestive tissue- absorbs particles from water
3 Phylum Porifera
Ostium
• Ostium • Choanocytes • Amoebocyte • Spicules • Spongocoel • Osculum
Phylum Porifera— 3 Body Plans
Asconoid Syconoid Leuconoid
Phylum Cnidaria
• Characteristics – Radial symmetry – Cnidocytes – Simple nerve net – Life cycle alternates between two forms • Medusa •Polyp
4 Cnidaria - body plan
Polyp Medusa
Cnidocyte
Operculum Cnidocil
Cnidocyte
Nematocyst
Class Hydrozoa - Hydras
• Polyps are the mature form
• Individuals or colonies
• Portuguese Man-o- war special colony
5 Class Hydrozoa - Hydras
• Prey on zooplankton
• You will observe Hydra feeding on Daphnia – Look at locomotion
http://www.youtube.com/watch?v=Kukv0AtIVdU
•Marine Mesoglea Gastric pouch
Gonad • Medusas: dominant life form
• Aurelia
Tentacles Ectoderm Endoderm Oral arms
6 Class Anthozoa • Anemones and corals
• Most complex cnidarians
• Always polyps
• Symbiosis with dinoflagellates
Class Anthozoa - Anemones
pharynx
coelentron
basal
http://www.emc.maricopa.edu/faculty/farabee/biobk/anemone.gif
Phylum Platyhelminthes- Flat worms
•Triploblastic
• Bilateral Symmetry
•Organs
• Sac-like gut
•Acoelmate –No cavity
• Monoecious
7 Class Turbellaria– Planarian spp.
• Free living
• Cephalization- – You can see where you are going – Brain center- coordinate movement
• Bilateral Symmetry = efficient movement
Class Turbellaria Planarian cross-section
Ectoderm Mesoderm Endoderm
Pharyngeal cavity Pharynx Gut
Gut Lumen of the pharynx Parenchyma
Class Trematoda-Flukes
• Life cycle with multiple hosts
• Parasites – Opisthorchis sinensis- Human liver fluke
8 Class Cestoda- Tapeworms
• Thin, ribbon-like
• Sections = proglottids
• Parasites
• 1 or 2 Hosts
Class Hydrazoa
Gonangia
Hydranth
Class Scyphozoa
9 Class Trematoda
• Life cycle with multiple hosts
10