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Invertebrates http://www.docstoc.com/docs/79739092/ Invertebrates-Section-1

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Invertebrates

http://www.docstoc.com/docs/79739092/Invertebrates-Section-1

Age of Inverts

• Age of Fishes

Age of Reptiles

Age of MammalsAge of Man

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

Beroe

Pleurobrachia

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

• 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

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

• 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