b2 lec t3

choanoflagellate.  Single (Monosiga) or Colonial (Proterospongia)

"side animals".  No tissues--cells not held together by junctions, etc.  No animal symmetry.  Porifera.  Sponges. 

"pore bearer".  Parazoa.  Sponges.  Marine (or fresh water)  No symmetry, specialized tissues or organs.  Sessile (larvae free-swimming).  Cells will reorganize and reform if disturbed. 

pinocytes.  outer epithelial layer of flattened cells and pores.  Responds to external stimuli. 

layer of flagellated cells lining inner cavity (spongeocoel). Set up a current to obtain food and expel waste. 

(sclerocytes)center region that contains spicules

sponge skeleton--jacks in mesenchyme made of calcium carbonate, silica or protein.  Support and give shape. 

(archaeocytes).  Motile cells for food digestion

animals with definite shape and symmetry.  Most have tissues. 

have two embryonic tissues: ectoderm and endoderm.  Also have mesoglia in center--gluey but not a tissue. 

gluey cells that are not tissues in between the endoderm and ectoderm of diploblastic organisms

• Radiata (radially symmetric with a center mouth) with a sac-like body and two tissue layers.  No organs. 
• Cnidocytes: stinger cells.  Consist of:
• Hydrazoa
• Schyphozoa
• Anthozoa
• Two forms (Medusa and polyp).  Larva stage is planula. 
• Carnivorous
• nerve net

Cnidarian (Radiata, Eumetazoan), with Cnidocytes.  Sessile polyps that release medusa-gametes. 

Jellyfish.  Medusa. Zygote is briefly a polyp

Polyps with no medusa form.  Solitary or colonial (Sea anemone is solitary and coral polyps are colonial--symbiotic relationship with zozanthelle). 

sessile and attached form of cnidarians.  Dominant in Hydrozoa and Anthozoa

free-floating form of Cnidarians.  Planktonic. Dominant in Scyphozoa. 

larval stage of Cnidarians. 

having 3 embryonic tissues: endoderm, ectoderm, mesoderm

head-end

tail-end

belly

back

side

tail

outside from

inside from

towards center

fish's face, dorsal to ventral

dorsal to ventral on side of fish

• better movement--more efficient food-gathering and retreat from predators, and finding a mate. 
• concentration of sensory structures will allow for a brain-end.  Allows nerve cord arrangement. 
• All bilaterally symmetrical animals are triploblastic

no body cavity

false body cavity

true body cavity, lined with mesdermal tissue on both sides, with mesentary and peritoneum

• mouth forms first, then anus
• spiral arrangment
• fate of each cell is fixed--if something dies, structure will be missing something. 

• anus forms first, then mouth. 
• Fate is not fixed. 

dorsoventrally flattened worms.  Acoelomic.  anal pores.  May or may not have a mouth.  Turbellaria, Trematoda and Cestoda

non parasitic flat worms with anal pores.  Pharynx like a flatworm.  Planarians (have triangle heads with sensory organs)

parasitic (flukes).  No sensory organs.  Hermaphroditic.  Pharynx and anal pores. 

Parasitic tapeworms.  No mouth or anal pores.  Scolex, neck and proglottids (segments). 

roundworms.  Mouth and anus.  Mostly separate sexes and parasitic.  "threadworms", boy has hook, female is big.  pseudocoelomic.  Ascaris (hookworm).  Also heartworm, pinworm, trichinella (muscle worm), Intestinal (hook?)

• Phylum Mollusca
• Phylum Annelida
• Phylum Arthropoda

• 3 body parts: head/food, visceral mass, mantle.
• 4 classes: polyplacophora (chitons)
• Bivalvia
• Gastropoda
• Cephalopoda

carbohydrate plate armor of Mollusca. 

Chitons (Mollusca).  Most primitive, chitinous plates, open circulatory system.  Invertebrates. Small, living on rocky outcrops.  Mouth, stomach, valves (plates), anus.  Hemocoel. 

blood cavity.  (Polyplacophora)

Clams, oysters, scallops (Mollusca).  Calcium carbonate (chalky) shell, open circulatory system.  Gills in mantle. 

One shell, stomach-foot (Mollusca).  Slug, Snail, Conch.  Visceral mass undergoes torsion (slug un-twists) so anus escapes shell in embryo.  Open circulatory system.  Teeth of chiton. 

Head foot (Mollusca). Shelled, reduced-shelled or shell-less.  Octopus (chitonous beak), Squid (reduced shell), Nautilus, cuttlefish.  Advanced CNS, nerve cord, eyes, closed circulatory system. Carnivores with chitious beaks

floating.  Like a jellyfish or medusa.  Not active swimmers. 

• Metamers and closed circulatory systems (red blood).  Paired nephridia at every metamer.  Breathe through skin.  Consist of:
• Polychaete
• Oligochaete
• Hirudinea

many bristels (Annelida).  Chitinous.  Live in water, reproduction is easy, 2 sexes.  Centipede-looking. 

2 bristles (Annelida).  True hermaphrodites.  Can fertilize each other--both walk away pregnant.  land-worms.  ventral nerve cord, clitellum (where eggs are), 5 heart loops, crop, gizzard, non-segmented intestine.  Cut apart, they'll make more. 

leeches (Annelida).  True hermaphrodites.  Back to the water.  Head sucker and foot sucker.  care for young. 

• Chitinous exoskeleton, classification based on Appendages, open circulatory system. 
• Ocelli and Ommatidia.  Molt to grow, go through metamorphosis to reproduce. 
• 4 subphyla:
• Chelicerata
• Crustacea
• Unirama
• Triblobitamorpha

Spiders, ticks, horseshoe crab, scorpion.  1st pair: chelicera (food-ripping), 2nd pair pedipalps (hand-feet), 4 walking legs.  Fused metamers to make cephalothorax (tagma).  No moving mouth-parts

light-sensing organs of Arthropoda (sense light and dark). 

Large seeing-eyes of Arthropoda are made of units called ommatidia and bristles.  Complex. 

• barnacle, shrimp, lobster, crab, crayfish.  Moving mouth-parts, paired appendages at each segment, 4 pairs of walking legs, fused cephalothorax, Biramous (2 branches at appendage). 2 antennae.
• barnacle is sessile. 
• 2 big pincers. 

• Arthropod.  3 classes:
• chilopoda
• diplopoda
• insecta

centipedes. 30 or more legs, 1 pair per segment, separate sexes, carnivores (toxic to humans). 

millipedes.  2 pair of appendages per segment.  60 or more legs, separate sexes, herbivores

Head with various mouth-parts, 3 pair of appendages attached to thorax, if there are wings, also attached to thorax, abdomen.  Breathe through holes in sides (spiracles are holes and trachea from them open into hemocoel). largest group of organisms on earth.  3 body sections. 

make uric acid crystals to conserve water in Insecta

Extinct trilobites.  Cephalothorax, jointed legs. 

simple or complex, all arthropods go through metamorphosis to reproduce. Uses ecdysis or moulting until adulthood is reached

juvenile resembles adult.  Wings develop externally with no resting stage.  nymphs until final molt: adult. 

wings develop internally during resting or pupa stage.  Juvenile looks and acts nothing like adult. 

process by which exoskeleton is shed by splitting the old cuticle along specific lines. 

(bees).  Each ommatidium acts independantly and are in the brain.  Image is inverted and ommatidium is surrounded by pigment cells

(moths).  Images from a series of ommatidia are combined on a cornea, the image is right side up, there are no pigment cells

leaf-like plates found in a chamber which draw in and expel air by muscle contractions

(Class Arachnida, Subphylum Chelicerata).  Pedipalps are modified into pincers.  Book lungs

Spiders. (Class Arachnida, Subphylum Chelicerata). Prey on insects and small animals with poison glands.  Spineretts on posterior of abdomen make webs. 

mites. (Class Arachnida, Subphylum Chelicerata). Most diverse, in every environment.  Oval-shaped, unsegmented body. 

Horseshoe crabs.  (Class Aracnida, Subphylum Chelicerata).  "Living fossils".  Grow large, lay in deep water, mate in sand.  Females lay eggs in sand.  Respiration is by book lungs.  Feed on Mollusks and annelids

sea spiders (Class Aracnida, Subphylum Chelicerata).  Small, parasitic or predators.  Sucking proboscis.  Use diffusion for respiratory and excretory action.