Requirements for Animal Life
•  The demands of 3 unique environments
–  Marine, freshwater, terrestrial
•
•
•
•
•
•
•
Gas exchange
Nutrition
Distribution and transport
Disposal of cellular wastes
Internal water and salt balance
Reproduction and development
Support and movement
Animal
phylogeny
based on
sequencing
of SSUrRNA
!
Radial symmetry
“Radiate" phyla
Phylum.
Cnidaria
Hydrozoa
Class. Scyphozoa
Class. Cubozoa
Class. Anthozoa
Class.
Phylum.
Cnidaria- jellyfish and anemones
Ctenophora
Phylum Cnidaria
hydras, jellyfish, sea anemones and corals
•  Radial Symmetry (mostly)
•  Diploblastic: Tissue level of organization
–  Ectoderm: outer layer  Epidermis
–  Endoderm: inner layer  Gastrodermis
1
Body wall
Dimorphic life cycle
Gastrovascular
cavity
Mesoglea (very thin)
Main Structures of Jellyfish
Cnidae
•  Protection and
food
•  Most complex
organelle in the
world
•  Explode at high
speed
•  Carry poisons and
other chemical
Nematocysts
Locomotion
•  Medusae swim
with muscles
•  Can ambush
prey
•  Can bring prey
to the jelly
2
Feeding
Distribution and Transport
•  Jellies eat many
different prey
•  Some specialize on
other jellies!
•  Some Farm for
Dinner
•  Canals and cell-to-cell
•  Nutrition, cellular wastes, gas exchange…
Senses and Nerves
Class Hydrozoa: colonial polyps*
•  The Jelly “Brain”
–  Nerve Net
• Sensory
Structures
– Eyes, Noses,
Tongues, Ears…
– In Scyphozoansthe Rhopalium
Hydroids
* Mostly
Rare Deep-sea Hydrozoans
3
Scyphozoan life cycle- Aurelia
“Alternation of generations”
Adaptive Value?
Colonial HydrozoansSiphonophores
By-the-wind sailor (Velella velella)
Siphonophores
Colony vs. Ind.
•  Entire colony from single cell, with asexual polyp
reproduction
4
Class Cubozoa
Class Anthozoa: anemones,
corals, gorgonians
•
•
•
•
Anemones
Shape of life…
Worldwide distributions
solitary or colonial
w/ or w/o exoskeleton
Some w/ algal symbionts
no medusoid phase
Coral Reefs
•  Occupy less than 0.2%
of planet, yet…
•  Have upwards of 5% of
all species
•  Use 50% of CaCO3 and
with it, CO2 to build
reefs; around 700 billion
kg/year out of atm.
•  Very productive areas in
a desert, extremely
diverse
Coral Polyps
5
Zooxanthellae
Symbiotic Dinoflagellates
Requirements for Animal Life
•  The demands of 3 unique environments
–  Marine, freshwater, terrestrial
•
•
•
•
•
•
•
Gas exchange
Nutrition
Distribution and transport
Disposal of cellular wastes
Internal water and salt balance
Reproduction and development
Support and movement
Phylum Ctenophora: comb jellies
Bleaching
Animal
phylogeny
based on
sequencing
of SSUrRNA
!
Fig. 13.36a
–  Comb rows
–  Colloblast cells
–  Bilateral
–  Three tissue layers
–  Complete Gut*
6
Cydippida
Lobata
Ctenophores- Comb jellies
Cl. Nuda
Beroida
Arctic Ctenophores
Ctenophores as invasive species
•  Mnemiopsis
–  Black Sea, Caspian Sea, etc…
Requirements for Animal Life
•  The demands of 3 unique environments
–  Marine, freshwater, terrestrial
•
•
•
•
•
•
•
Gas exchange
Nutrition
Distribution and transport
Disposal of cellular wastes
Internal water and salt balance
Reproduction and development
Support and movement
7