- compare ingroup to close species that is not part of the group

-shared characteristic between ingroup and outgroup are considered to be shared ith common ancestor

embryo is initially a blastula

sex cells are formed in specialized organs

motile sperm

all except porifera have germ layers

two sided symmetry

3 germ layers (ectoderm, mesoderm, endoderm)

(first mouth)

blastopore forms mouth

spiral cleavage

mesoderm makes solid bands along body axis, then hollow out to make body cavity

blastopore forms anus (invagination forms mouth)

radial cleavage

mesoderm starts out a out-pocketing of gut cells, which breaks out and is already hollow

Dorsal notochord

Dorsal hollow central nervous system (nerve cord)

postanal tail

pharyngeal pouches

endostyle

slender rod of living cells ventral to nerve chord and dorsal to alimentary canal

hydrostatic organ

(only embryonic in vertebrates)

derived from ectodermal neural plate by invagination

hollow along entire length

nerve tissue surrounds neurocoel

ciliated, mucus-secreting groove in ventral surface of pharynx.

aids in transporting food to esophagus and metabolized iodine

all characteristics of chordata

suspension feeders

endostyle also fixes iodine

characteristic of all vertebrates

regulate development

order is always the same, but number can vary between species

formed by invagination of neural plate

cells are at the border between neural plate and epidermis

form placodes that give rise to all complex sensory organs and lateral line system

form cranial nerves and most of peripheral nervous system

pigmented cells in skin

secretory cells in gut

smooth muscles in blood vessels

muscles, skeleton, mesentery, connective tissues

urinary and reproductive systems

coelom

somites during development

splanchocranium

chondrocranium (cartilaginous neurocranium)

dermatocranium

arises from neural crest cells

builds a series of arches tha lead to different structures

basibranchial

hypobranchial

ceratobranchial

epibranchial

pharyngobranchial

in mammals, plates never reach surface of the skin (subdermal plates - skull bones)

in bony fish and tetrapods: roof of skull and shell around chondocranium, maxilla, premaxilla, bones of lower jaw, temporals, parietals, palatine bones

living cells in lacunae within extracellular matrix

extracellular matrix consists of ground substance (chondroitin sulfate) and fibers (collagen)

hyaline (glassy, homogenous, most common)

fibrocartilage (clearly visible fibers)

elastic cartilage (such as outer ear)

matrix consists of highly ordered calcium phosphate deposits

each osteon: haversian canal with cells blood vessels, lymphatic vessels, and enrves

Conodonts

Ostracoderms

Hagfishes

Lampreys

Jawed Fish (Gnathostomata)

subgroups

Placodermi (oldest)

chondrichthyes - cartilage fish

teleostomi

Jawed fish

bony plates covered by skin

very powerful jaws

successful species

Acandthodii (spined fish)

osteichtyes (bony fish)

actinopterygii

sarcopterygii

Gills in Chondrichthys

specialized kidneys to continually get rid of water

ion pumps to move ions into cells so to minimize loss in urine

300 mOsm

continuous water loss

-instantaneous physiochemical buffering

-respiratory adjustments of the co2-hco3 buffer system

-net transport of acid/base relevant molecules between animal and environment

rete mirabile

oxygen binding capacity of hemoglobin increases with increased pH. System uses H+ secretion and countercurrent exchange to regulate O2 binding.

positive feedback causes plasma to become saturated with free O2 until it diffuses out to swim bladder

protective layer around swim bladder prevents oxygen from leaving.

sphincter muscle can open to let oxygen out and back to blood stream

cornea does not contribute to light breaking, so lens must be round for maximum breaking power

lens moves back and forth to focus

several hair cells covered by cupula

found on surface of all fish

in many teleosts, most are located in lateral line system

modified muscle cells - up to 10,000 in series

specialized cells that cannot be depolarized on one side, so there is a charge across the cell when one side depolarizes

since they are in series, they produce an additive electrical discharge

when electric field comes in contact with an object that has different conductivity than water, the fish sense the change with electroreceptors

can also be used for communication

Elasmobranchii

Neoaoselachii

 sharks

                                       Galeomorpha (with anal fin)

                                      Squalomorpha (no anal fin)

                             Batoidea - rays and Skates

         Holocephali - ratfishes

most are predators (few filter feeders)

eat 3-14% of body weight per week

males and females often hunt in unisex groups

lay eggs in leathery egg case

when eggs are laid, shark is almost ready to hatch

-nourished by uterine milk after hatching

-trophonemata - extensions of uterus into esophagus of offspring

-oophagy - eating unfertilized eggs

Adelphophagy - cannibalism in utero

-Placental - yolk sac undergoes transformation and atteches to uterus to form placenta

oldest known shark species

2 known scales (.4 mm wide)

about 455 million years ago

Late ordovician period

earliest teeth found - 400 million years old

earliest articulated skeleton - 100 million years old

about 370 million years ago

unusual and specialized

- high aspect ratio tailwith transformed stretch of vertebral column supporting upper lobe

-large pectoral fins supported by broad straplike cartilages (primitive)

23.3-5.3 million years ago

(Miocene and Pilocene)

third largest fish species known

ovoviviparous

filter feeder (teeth are not for predation)

worldwide distribution

Great white shark

Sarcopterygii - fleshy fins

Actinoperygii

coelacanthiformes

dipnoi

tetrapods

neopterygii

teleostei

euteleostei

terminal mouth

braincase narrow

three otoliths

Large eyes

bony spines in fins

endochondral bone

lepidotrichia

distinct bones in jaw

ray finned fishes

largest group of vertebrates

most are teleosts

sarcophterygii characteristics

lobe-finned fishes

complex enamel

Massive skull roof

unique palatal teeth

all freshwater

estivation

Australian: gills

African/South American: lungs for O2 uptake