subphylum urochordata 

have chordate larval forms - have notocord, dorsal nerve cord, tail, and pharyngeal slits - adult form only has pharyngeal slits

ancestors to vertebrates (which are a subphylum of phylum chordata)

bilateral symmetry

deuterstomes

sea squirts from North Atlantic

dorsal hollow, nerve cord

deuterstome coelomates

ancestor to vertebrates (subphylum of chordata)

4 characteristics - nerve cord, notochord, pharyngeal slits, postanal tail

bilateral

dorsal, hollow

lies in dorsal position above digestive tract and notochord (unlike annelids/arthropods which has a solid nerve cord below digestive tract)

hollow - fluid filled central canal (neurocoel)

below nerve cord

hydrostatic, elastic organ that resists compression but is laterally flexible

contains connective tissue sheath, collagenous sheath, and vacuoles in notochordal cells

lies above body cavity and is axially incompressible (resists shortening in length)

prevents collapse of body and muscle contractions on alternating sides efficiently flex the body in swimming strokes

connect pharynx (mouth tube) to external environment

more like pouches for terrestrial vertebrates

allows water entering mouth to exit body without passing through entire digestive tract

extends beyond anus

provides propulsion for many aquatic species

tail lost during embryonic development in many chordates (Homo)

subphylum cephalochordata

brain

450 mya

first fishes

subphylum myxini - jawless fish

lack paired appendages

brain with a cranium or skull of cartilage

notochord persists in adults

subphylum vertebrata

first vertebrates - cephalaspidomorphi

cartilaginous pipe surrounding notochord

cartilaginous projections extend from pipe upward and paritally enclose dorsal hollow nerve cord

fastens onto its prey and rasps out a hole with its rough tongue

anicoagulant in the lamprey's saliva keeps the wound open for hours or weeks, until teh lamprey is satiated or the host fish dies

545 mya

vertebral column - replaces notocord

head - brain with 3 pairs sensory organs

neural crest - cells develop many structures

internal organs - closed circulatory system, unique excretory system

endoskeleton - cartilage or bone (strong but not brittle like chitin)

1. cartilaginous fish

2. ray-finned fish

3. coelacanths

4. lungfishes

5. tetrapods - amphibians

modification of existing structures

420 mya

skeleton of the jaw and supports evolved from two pairs of skeletal rods located btw gill slits that were near the mouth - pair of rods anterior to those that formed teh jaws were either lost or incorporated into the jaws

gills behind mouth supported by series of cartilage arches - in btw them were gill slits

jaws evolved from 1st gill arch on either side - folded over and joined in the midline to form upper/lower jaws

teeth - developed from skin that lined mouth

acanthodians - first vertebrates with jaws (420 mya)

devonian period - "age of fishes" (360-400 mya)

all extinct - later out - competed by bony fishes (360 mya)

first gnathostomes (jaw mouth)

sharks, skates, rays, stingrays, chimaeras

dominant predators (evolution of jaws)

highly mobine (evolution of 2 pairs of fins)

out-competed later by marine reptiles (Ichthyosaurs and Plesiosaurs)

actinopterygii - ray-finned fishes

actinistia - lobe-finned fishes

diploi - lungfishes

yellow perch - rays in dorsal fins, operculum, lateral line, pelvic fins, pectoral fins

long-snouted sea horse

thought extinct until caught 1939 in south africa

ancient characteristics - well developed notochord, fleshy appendages, divided tail

has both lungs and gills

evolved lungs connected to pharynx (retained gills)

inhabit stagnant ponds (low oxygen)

habitats dry out - burrow mud to aestivate (summer sleep)

secrete skin mucus, hardens, forms cocoon (to resist water loss)

dominant predators in shallow freshwater habitats

ANCESTORS to AMPHIBIANS and all other TETRAPODS

1. 415 mya - eusthenopteron - fleshy-finned fish

2. 400 mya - panderichthys - fleshy-finned fish, lacks dorsal and anal fins

3. 380 mya - acanthostega - labryithodont - ancient tetrapod - 4 footed fish with weight-bearing girdles; internal gills and lungs; aquatic

4. 370 - ichthyostega - tetrapod - no internal gills; lungs; aquatic when juvenile; terrestrial when adult

5. balanerpeton - tetrapod - more ossified limb girdles and limbs

fish with tetrapod limb skeletal structure - 380 mya

fish - devonian tetrapod

aquatic vertebrate with gills as adult; appendages had tetrapod skeletal structure

200 mya

monophyletic

salamander, frog, caecilian

adult skin must be kept moist

dessication (drying out) of body and respiratory structures

desiccation (drying out) of gametes, eggs

gravity

sensory organs go from water to air

feeding/excretion

jelly-covered egg must be kept moist - 1 extra-embryonic membrane

inside is the yolk which has the embryo

salamander, frog, caecilian

male grasps female frogs

egg-guarding frogs

foam nest builders

specialized sites for egg deposition

parental care: mouth-brooding frogs

dorsal carrying of eggs

parental care: gastric-broodig frogs

live-bearing frogs

parental care - dorsal carrying of tadpoles

pustulosus

foam nest builders

protein protects from drying and provides antibacterial protection

goldent rocket toad (costa rica)

threatened by ongoing forest loss

deposit eggs in bromeliad plants, larvae develop in puddles of water

parental care - darwins frogs

females deposit eggs in leaf litter

once eggs start to move, adult males ingest eggs and incubate in vocal sacs

larvae development inside male and merage after metamorphosis

pipa

eggs carried by being imbedded in dorsum of parent

parental care - southern gastric-brooding frog

extinct - australia - family rheobatrachidae

females brood the larvae in their stomachs and give birth to froglets through the mouth

tanzania - threatened by forest loss

gives birth to live young (viviparous)

parental care

tadpoles carried on male's back by adherent ventral surface

1. chorion

2. amnion

3. yolk sac

4. allantois

outermost membrane - lies below porous shell

allows exchange of respiratory gases btw embryo and environment - retains water

protects embryo in fluid-filled cavity

prevents dehydration and cushions mechanical shock

disposal sac

surrounds a cavity into which waste products from the embryo are excreted

develops inside eggshell - keeps it from drying out but allows for gas exchange

chorion and allantois fuse to form chorioallantois membrane (facilitate embryonic breathing)

tetrapods evolved from freshwater bony fishes and are highly aquatic

reptiles evolved from Anthracosaurs (divergent group of tetrapods)

first amniotes are reptiles - amniotic egg and horny scaled skin

transition from shallow water/water side species to abundant and diverse terrestrial species occured during Carboniferous period

1. anapsid - no temporal hole

2. synapid - one lateral temporal opening

3. diapsid - two temporal openings (lateral and dorsal)

220 to 65 mya

reptiles were dominant animals for about 200 my

1. land - herbivorous vs. carnivorous

2. flying - pterosaurs

3. marine, freshwater - plesiosaurs, ichthyosaurs

all descendents (birds, crocodiles, snakes, lizards, turtles) sharing teh same ancestor are included

mammals stem from horny scales directly; others mentioned stem from an ancestor with keratinzed skinn

amniotes

lack parental care

bury eggs to prevent drying out and overheating

arribada (arrival) at playa ostional, costa rica

density of nesting affects hatching success

amniots

parental care (protects them bro)

206 mya

shrew-like

amniotes

parental care

evolved from diapsid reptiles

missing link between reptile (teeth, many-boned tail, solid bones, unfused) and bird (light body, feathers)

150 mya

amniotes

crocodiles are more ecologically similar to birds than other reptiles (build nests, parental care, four chambered heart)

direct descendents of dinosaurs - resembled small theropods (small T-rexs)

exponential decline of leatherback turtles (nesting decreased)

endangered - in 20 years, went from 115,000 adult females to 30,000

1. fishing - gill nets and long lines

2. development of beaches - no nesting beaches, no turtles

3. taking of eggs - poaching

1. feathers

2. lightweight skeleton - fused hollow bones

3. no teeth

4. large breast muscles

5. keeled breastbone, fused collarbone

6. retain amniotic egg

7. retain horny scales on feet and lower legs

8. endothermic, high metabolism, efficient circulation, 4 chambered heart

most diverse terrestrial vertebrate group

28 orders, 166 families, 8600+ species

elephant bird egg is HUGE - 27 pounds

ruby throated humming bird egg is like a marble

ostrich egg is like a child's head

clutch size is maximum number of young that parents can feed or care for

clutch of eggs - all eggs produced by bird/reptile at a single time

clutch size 1

benefits quality - 300-450 g/egg - increased offspring size

greatest egg mass/body ratio of any bird species

egg is 26% of body mass

clutch size 9-27

21-30 g/egg - more offspring

benefits quantity

small clutch = increased quality, larger offspring

large clutch = increased quantity, more offspring

natural selection is those in middle

single bone on either side of lower jaw

hair - mammary glands

reptilian to mammalian

ectothermy vs. endothermy

horny scales vs. hair (insulation)

low metabolism vs. high metabolism

small jaw muscle vs. large jaw muscle

homodont teeth vs. heterodont teeth

no secondary palate vs. secondary palate

parietal foramen vs. no parietal foramen

(teeth and jaw muscle evolve at same time)

ancient - larger girth, more circular, large-cannine like tooth, temporal fenestra is small

recent - longer rather than girthier, large dentary (complex postcanine teeth), larger temporal fenestra

1. subclass prototheria (O. monotremata) - monotremes (lay eggs)

2. subclass theria (infraclass marsupialia)

3. subclass theria (infraclass eutheria) - placental mammals

5 species

echidna, duck-billed platypus

retention of reptilian characteristics (lay shelled eggs; pelvic and pectoral girdle reptile like; cloaca: opening for feces, urine and eggs)

289 species

kangaroo, koala, opossum, etc.

1. no shell around egg - just amnion and chorion

2. short-lived placenta around chorion

3. embryonic marsupial born; crawls into pouch; fed by mammary gland

4. two juveniles of diff ages can be nourished simultaneously

5. immediate replacement if one dies

about 5200 speices - everything else

placenta nourishes embryo throughout development (fetal and maternal blood vessesl present; formed from chorion and allantois)

1.5 gram to 100,000 kg whale

long embryonic development period before being born

SKELETON - has huge, cumbersome antlers - runaway sexual selection (females attracted to larger antlers, but harder to escape predators, mortality increases)

or climate change

apes - smaller braincase, smaller forebrain, fewer sinuses

humans - larger braincase, larger forebrain, more/extensive sinuses

fossil found on island in indonesia

may have evolved from homo erectus - hobbit man - descent through modification

island dwarfism - limited food, fewer predators, isolation from mainland

natural selection:

1. variation exists in populations of organisms

2. certain traits are favored over others

more success at reproducing, higher survival rate, change in allele frequences over time

leads to microevolution, may lead to macroevolution