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

Age of Man Age of Mammals Age of Reptiles Age of Inverts 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 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