Invertebrates
http://www.docstoc.com/docs/79739092/Invertebrates-Section-1
Age of Man
Age of Mammals
Age of Reptiles
•
Age of Fishes
Age of Inverts
http://hotelcondesdeharo.com/contacto/time-periods-dinosaurs
Shapes:
Tiny cups, broad branches, tall vases, encrusting round masses
PORIFERA-sponges
• Most primitive multi-cellular organisms
• No symmetry
• Aggregate of independent cells, lack tissues
and organs
• Sessile and filter feeding
• 10,000 species and three classes based on type
of spicule
Amebocytes
• A wandering cell that
secretes materials for
building a sponge
Choanocyte/Collar cells
• Cell w/ flagella that creates
a water current through the
sponges ostia. The sponge
obtains its nutrients and
oxygen by processing this
flowing water
Osculum
• The large opening through which water exits
Ostia (ostium plural)
• Water flows thru these
tiny pores
Pinacocytes
• the sponge's outer layer of cells / “skin”
Porocytes
• cells with pores that allow water into the
sponge; they are located all over the sponge's
body
Spicules
• spicules are sharp spikes (made of calcium
carbonate) form the "skeleton" of many
sponges.
Fig. 7.7
CNIDARIA
• First animals to move-primitive nervous
system and muscle tissue
• First animals to have a space for digestion
• Radial symmetry and stinging tentacles
• 4 classes: Anthazoa, Hydrazoa, Scyphazoa,
• Two body types: polyp and medusa
Pleurobrachia
Beroe
CTENOPHORA
• Probably an offshoot of Cnidaria, similar body
plan
• Biradial symmetry
• Ciliary combs and sticky tentacles for
catching prey
• Known for bioluminescence
Bell
• free-swimming umbrella-shaped body
Ciliary Combs
• Cilia on a comb jelly that help them swim
Colloblasts
• Sticky tentacles of a comb jelly / for catching
prey
Medusa
• a form of cnidarian in which the body is
shaped like an umbrella.
Polyp
• Polyp is the sessile form of the cnidarians with
more or less a cylindrical body shape.
Nemotocysts
• Stinging cell of cnidarians
Nerve Net
• Simple nervous system in Cnidarians
Statocysts
• Cells that give a sense of balance/ orientation
in the water column
Worms on
• Bilateral symmetry in all the rest of the invert
groups from this point on…
• Worms are first groups to develop complete
digestive tract, blood vessels, body cavity,
headlike area, and a coelom
• Most are soft bodied, live in tubes and deposit
feed or suspension feed.
FLATWORMS
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Most primitive bilateral animal
Acoelomate- no body cavity /solid body
Trematoda and cestoda classes are parasitic
Turbellaria are carnivorous, many have eyes
Incomplete digestive tract
NEMERTEANS
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Offshoot of flatworm groups
Acoelomate- no body cavity /solid body
Simple circulatory system with blood vessels
Complete digestive tract
Proboscis for catching food- may be poisonous
and barbed
– Entirely carnivorous and prey on annelid worms
and small inverts
NEMATODA
• Pseudocoelomate- not a true body cavity but a
similar fluid filled space
• Complete digestive tract
• Some of most widespread and numerous
multicellular animals
– 1 m2 of mud can have up to 4,420,000 in it
• Covered by scales or cuticle
• Free-living and parasitic species
Leech
Sabella pavonina
Nereis sp.
Lumbicus terrestris
ANNELIDA
• Segmented worms- important in increased
mobility and evolution of appendages
• Largest worms and most differentiated
• Coelom
• Head-like area
– Polychaetes-parapodia on each segment, some with
poisonous bristles, gills, eyes and sensory organs on
head
– Many feeding methods
– Hirudinea-leeches: parasitic
MOLLUSCS
• Second largest invert phylum and fossils back
to the Cambrian era
• Diversity of form based on an ancestral body
plan: bilateral symmetry, head with tentacles,
muscular foot for locomotion, shell-excreted
by mantle tissue, radula for feeding, open
circulatory system in most and coelom
• Gastropoda, Bivalvia, Cephalopoda
Mollusc Annelid Connection
• Similar larvae
• Similar segmentation in the Mollusc group
monoplacophora
ARTHROPODS
• 80% of all known species
• Chitinous exoskeleton-molted for growth
• Jointed appendages but tendency towards
reduction in number and more specialized in
use
• Small coelom, open circulatory system, high
degree of cephalization, well-developed sense
organs and behaviors
• Subphylum chelicerata and crustacea
• en.wikipedia.org
en.wikipedia.org
Chelicerata
• Body lacks antennae, divided into
cephalothorax and opisthoma
• 5 to 6 pairs of walking arms and book gills
• Chelicerae –feeding appendage
– Merostomata- horseshoe crabs
• scavengers and feed on molluscs, worms and bottom
dwelling algae
– Pycnogonida-sea spiders
• Also have proboscis for feeding
• Exclusively bottom dwelling
Mollusc-Annelid Connection
• Similar embryology
• Similar segmentation in a group of molluscs
called monoplacophores
• Molecular evidence
Arthropod-Annelid Connection
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Similar segmentation
Similar appendaging like polychaets
Embryology
Similar organ system arrangement
Crustacea
• 2 pairs of antennae, mandibles, maxillae, and
compound eyes
• Areas of body are specialized by region and in
some cases fused together
• Biramous appendages
• Great range of diet and even some parasitic
examples
ECHINODERMS
• Only major invert group that is a
deuterostome.
• Entirely marine and largely bottom dwelling
• 5 part radial symmetry but start life as
bilateral larvae
• Endoskeleton of calcium carbonate
• Water vascular system for locomotion and
attachment