Biology Chapter 34

763, 000 vertebrae vs. 10^6 Insect species

oldest animals ( some symmetrical or asymmetrical, don't have layers)

oldest true animals ( have radial symmetry, diploblastic)

most diverse body plans (are acoelomate, coelomate, and pseudocoelomate)

molters, most species rich animal group, individual numbers largest group

• most disparate species ( widest range of difference in characteristics)
• wide specetrum of chracteristics, ex: body mass
• largest animal on earth is a vertebrate and smallest animal on earth is a vertebrate

notochord, hollow nerve chord, pharyngeal clefts/slits, muscular post-anal tail

long flexible rod, located between nerve cord and digestive tract, made up of mesodermal cells, main funtion is to provide skeletal support ( allows animal to swim , provides firm flexible structure for swimming, skeleton vertebrae forms around notochord, in humans becomes gelatinous disk material found between the vertebrae ( distributes hydrolic pressure because of the compressive loads)

• unique to chordates
• made up from rolled up ectoderm
• ultimately develops into the central nervous system

• allows direct access to outside of the body
• invertebrates: pharygeal slits allow water to flow through for suspension feeders or filter feeders
• vertebrates: ( not tetrapods) these slits form into gills for gas exchange
• tetrapods: clefts do not develop into slits instead help form ears and parts of the neck and skull

• skeletal elements and muscle
• propulsion in water
• ex: lancelet, grows to about 5 cm max. , classic chordate body plan
• ex: tunicate development, looks like a chordate but as it deveops into an adult the tail and notochord are resorbed
• nervous sysem degenerates completely
• remaining orgas rotate 90 degrees
• have 9 hox genes, all other animals have 13
• during development goes through radical changes adult and anything pre-adult look nothing alike

• have vertebrates and invertebrates
• ex: tunicate
• have genes that encode for the heart and thyroid
• craniate is a type of chordate with a head

• chordates with a skull
• have 2 clusters of hox genes
• duplication in transcription and signaling molecuels
• neural crest is unique to craniates cells are from parts of the skull
• pharyngeal clefts in aquatic craniates: become gills for gas exchange
• terrestrial craniates=form other body parts
• have higher metabolism compared to other animals
• more extensive muscular system, ex: digestive system
• more developed ciruclatory system
• has heart with 2 chambers and redblood cells
• has kidneys to remove waste from blood

lack genes that encode for heart and thyroid

• oldest craniates
• least developed
• skull made out of cartelidge
• have brain
• are chrodates
• have ears and eyes
• have nasal opening connected to the pharynx
• marine bottom dwelling
• have slime gland that make slime that absorbs water
• can make several liters of slime per minutes
• possible stem blood flow in surgery in future?

• duplicationin in Dlx family of transcription factors
• more extensive skull
• back bone of vertebrae ( developed back bone)
• majoriy of vertebrates (spinal chord enclosed by vertebrae, replaced function of notochord)
• aquatic vertebrates have acquired fine ( dorsal ,ventral, anal for streering)
• ex: gnathostomes

• ex: gnathostome ( jawed mouth), ancestors of modern animals like sharks rays fishes, reptiles, amphibians, mammals
• have jaws,
• have enlarged forbrain which leads to better vision and sense of smell
• have lateral line

chondrichthyans and osteichthyans

• cartilage fish
• ex: sharks, skates, rays, ratfish

• oviparous
• ovoviviparous
• viviparous

lay fertilized eggs, eggs hatch externally

fertilized eggs are inside female then hatch inside female ( not live birth), in hard casing called mermaid purse

no egg casing, live birth, embryos feed off of placenta

bony fish has 2 groups: ray finned and lobe finned

fin is fanned you can see individual bones used in fins for swimming

• fin looks like bone but is actually muscle surrounding rod shaped bones can be used for crawling
• ex: coelacanths, lung fish and tetrapods

organ on each side of the animal to developement of senses motion in the water, function: to sense vibration or motion in the water , then the animal can tell where things are in it's surroundings

• four footed
• have individual digits on limbs
• head separated from body by neck
• pelvic bones are fused to the back bone
• no gill slits
• pharygeal clefts develop into ears and skull ( parts)
• ex: amphibians

• 1st part of life in water
• 2nd part of life on land
• different orders : frogs , toads, salamanders, caecilians ( leg less almost blind , spend life underground)
• skin: used for gas exchange
• undergoes radical metamorphosis

• starts out as a tadpole with gills, lateral line, tail, no lungs , herbavorious, aquatic, undergoes metamorphosis
• during metamorphosis: has legs, lungs, no gills, no tail (resorbed) has external ear drums, no lateral line, develops digestive tract, becomes terrestrial
• returns to water for mating, females lay eggs and male use external fertilization
• reproduction is oviparous, ovoviviparous, and viviparous

• composed of reptiles and mammals
• reptiles include avian and non-avian

• has amniotic egg
• a shell
• rib cage

• 4 parts
• amnion: fluid filled compartment shock absorber ( prevents injury)
• chorion: involved in gas exchange
• yolk sac: nutrients to feed embryo
• allantois: dual function of gas exchange with chorion and removes waste from the embryo
• pretty revolutionary
• it was a response to not having water

• non avian reptiles has a leathery flexible shell
• birds have hare calcerous shells
• mammals have no shell ( in utero)
• main function of shell is to prevent dessiccation ( dehydration)

can be ectothermic or endothermic

• crocodiles, alligators, tortoises, non-avian
• heat up from the outside using external sources of heat ( sun) use external sources of heat to regulate body temp. more than internal metabolism
• requires less energy= restricted to geography ( can be only where there are external sourches of heat)

• avian
• use internal metabolis more than external sources for heat
• requires more energy=requires more feeding
• more mobile

• have mammary glands=milk production
• hair
• layer of fat under skin to retain body heat
• 4 chambered heart for more effcient respirtory and circulatory system
• diaphragm ( ventilate lungs)
• relatively large brain
• differntiated teeth
• varied diet
• classified into monotremes, marsupials and eutherians

• only found in australia and new guinea
• lay hard shelled egges
• have mammary glands but lack nipples so you suckle on mothers furr
• ex: platypus

named for pouch they have , being development in utero then travel to marsupium, to develop completely

special external pouch on mom, young will literally migrate to continue development will nurse during this time suckling milk

placental mammals, mammals that have true placenta, longer pregnancies, embryo develops comepletly in utero, and feed off placenta