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 evidenceArthropod-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