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Chapter 34: Invertebrates

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Four Characteristics of all Chordates
Notochord, Dorsal Hollow Nerve Cord, Pharyngeal Slits, Muscular post anal tail
Notochord
long flexible rod between digestive tract and the nerve cord, important for skeletal support, develops into more complex structure in adults
Dorsal Hollow Nerve Cord
developed from ectoderm into the central nervous system (brain and spine)
Pharyngeal Slits
grooves within the pharynx, develop into opening of body, Function depends on animal
Invertebrate Pharyngeal slits
function in suspension feeding
Vertebrates Pharyngeal slits
gas exchange
Tetrapod Pharyngeal slits
develop into parts of ear, neck, and head
Muscular Post anal tail
most are reduced or absent as adult
Lancelets
- Invertebrate Chordate group,
- Named for Blade-like structure
- Marine suspension feeders,
- Segmented muscle and tail for swimming
- Traits develop during embryonic stage
Tunicates
- Invertebrate
- Larva stage has all 4 characteristics except Notochord and tail absent in adult
- Pharynx with slits allow for suspension feeding
Craniate, Chordats that have a head
1. Two cluster of Hox genes (regulate animal morphology)
2. Neural Crest - cells located in neural tubes that gives rise to specific structures
- have heart with at least 2 chambers, kidneys, extensive muscle system which allows for controlling complex coordinated movement
Hag Fish
- least derived surviving cranial lineage
- invertebrates
- Cartilagous skill
- small head, eyes, nose, and brain
- Slime glands - important for preventing predators attack
Lampreyes
- oldest living lineages of vertebrates
- have all characteristics of chordates
- have vertebrae which enclose spinal cord, elaborate skull, more complex nervous system and complex skeleton
- fin ray - stiffens the finds, increase speed of swimming and gas exchange at the gills
- jawless vertebrae
First trait vertebrates developed
presence of jaw
skeletal rods gave rise to
hinged jaws
gnathestomes
jawed vertebrates
common characteristics of gnathestomes
- more Hox gene
- enlarges fore-brain associated with enhanced smell and vision
Chordichtyars (sharks, rays, etc.)
- cartilage skeleton developed secondary to mineralized skeleton
- water ring helps with movement
Sharks
- swift swimmers - use tail and trunk fins
- do not have lungs - gas exchange at gills
- spiral valve - no true stomach, found in the intestine, increase surface area and passage time of food through the digestive tract
Shark reproduction
- internal fertilization but three ways to develop
1. shark lays egg that hatch outside mother
2. fertilized eggs retained within mother in oviduct, and eggs nourished by egg yoke
3. embryo develops in uterus of mother, gains nourishment from placental
Ray Finned and Lobe finned fish
- gnathestomes
- Oslecthyes - include lobe fish and Tetrapod
- swim bladder - important for bouyancy
- operculum - flap that used to protect gills, helps with gas exchange, protects gills
- Lateral line - all organs line up on
Bony Fish
- First vertebrates to have lungs used for air supplementation for gas exchange
- Ray finned fish - tuna and trout
Lobe Fined
- tetrapod evloved from
- Characteristic feature in fin - within fin have rod shaped bone covered with muscle
- three lineages: Coleacemiths, Lungfishs, tetrapod
Lung fish
internal skeleton, no true stomach, have spiral valve
Tetrapod
- gnathostomes that have limbs
- during Paleozoic era - fin of some lobe finned fish evolved into limbs and feet
Specific body adaptations of Tetrapod
1. Four limbs with feet that have digits, important for walking
2. Evolved to have ears, to listen for predators, came from pharyngeal slits
3. Have neck, head, can move
4. Increased reliance on the lungs for gas exchange
Amphibians
- tetrapod
- have retained structure that allow them to survive in water (gills and tails)
- aquatic and terrestrial habitat (aquatic larva)
- undergo metamorphosis - develop lungs, ears, and digestive system
Three orders of Amphibians
1. Salamanders
2. Frogs
3. Order Apoda
Frogs
- have more specialized movement on land, lack tail
- tadpole is aquatic
- fertilized eggs in two places: release sperm and eggs into water to develop, or mobile nursery ( carried by frog on back/mouth)
Salamanders
can be aquatic or live on land, unique feature: retain tail as adult
Order Apoda
evolved from legged ancestors, but trait was lost over time, not snakes
Amniotes
- includes reptiles, mammals, birds
- have terrestrially adapted eggs = more layers
- four specialized membrane - protection of embryo and allow it to develop on land
- reptiles: Para reptiles (extents) Turtles (box like shell, fused vertebrae)
Amniotic eggs
- tissues layers that evolve from outside embryo
- function: protection, gas, exchange, nutrient exchange and waster removal and storage
Amnion
membrane that enclosed the fluid sac
Allantois
membrane responsible for waster removal
Chorian
membrane that function with the allantois membrane for gas exchange
Yolk sac
nutrient storage and exchange with the membrane
Reptiles
- most are cold blooded - cant regulate temperature through metabolism
- ectothermic - absorb heat
- endothermic - able to maintain body temperature through metabolism
- reptiles have scales that create a waterproof barrier of keratin
- also include bird - not cold blooded, endothermic
Type of reptiles
- evolved from legged ancestors
- huge diversity in morphology and size
Birds
- classified as reptiles
- endothermic
- adpatations that help with weight - hallow bones, fused metacarpals, strong pectoral muscles, digestive tract is short, reduced tail, network of bones, feathers are aerodynamic
Characteristics features of bird
- well developed brain, respiratory, circularly systems - important for metabolism
- flight good for hunting, moving
Mammals
have everything as everything else plus hair and are amniotes that produce mile, endothermic, different circulatory and respiratory system
Four derived Characrteristcs of mammals
1. Mammmary glands that produce milk
2. Hair and layer of fat below hair
3. Large Brains
4. Differentiated teeth
Three Linegaes of Mammals
1. Monotremes - small lineage, egg laying mammals
2. Marsupials - second, have milk produced by nipple, refers to any animal with a pouch, embyro develops in placenta but born early and develops rest of the way in the pouch
3. Eutherians - placental mammals, no pouch, longer pregnancy, more complex placent, embyronic development within uterus
Primates
- order with the mammals
- includes lemurs, monkeys, apes
- Characteristics - opposable thumbs, forward facing eyes, well-developed brains, omnivores
Special for apes and monkey
long, arms, short legs, no tail, large brain to body size ratio
Derived Characteristics of Humans
1. Upright posture
2. Bipedal locomotion
3. Use of complex tools
4. Capable of language
5. Reduced jaw and jaw muscles
6. Large Brain
7. Shorter digestive systems
evolved first
bipedal locomotion
evolved second
use of complex tools
evolved last
large brain
sister taxa to humans
Neanderthals
Australepiths
relatively small brain size, have upright posture and used tools
Neanderthals
sister taxa to humans, thick boned with larger brains
Homo Sapiens
only living species of group, appeared in Africa
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