invertebrates
TRANSCRIPT
Age of Inverts
• Age of Fishes
Age of Reptiles
Age of MammalsAge of Man
http://hotelcondesdeharo.com/contacto/time-periods-dinosaurs
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
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
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.
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
CTENOPHORA
• Probably an offshoot of Cnidaria, similar body plan
• Biradial symmetry• Ciliary combs and sticky tentacles for
catching prey• Known for bioluminescence
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
• 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
• 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
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
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
• 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