Chordates

chordates

Echinoderms and chordates, mouth develops last 

Major vertebrate groups

  • Fishes

  • Amphibians

  • Reptiles

  • Birds

  • mammals

What four features do all these chordates have in common (all found in the embryonic stage) 

  • Notochord (entire body)- becomes backbone

  • Pharyngeal slits (gill pouch)

  • Hollow nerve cord

  • Tail 

Fishes

Two groups

  • Cartilaginous skeleton

  • Bony fishes

  • Bout half of all vertebrate species

  • Skates and rays (cartilage)

Characteristics

  • gills

  • jaws(most) and paired appendages (fins) 

  • Operculum, swim bladder (bony fishes)

(bony fishes) Operculum- protects the gills, the fish can open and close them so they can obtain water to obtain oxygen 

(Bony fishes) Swim bladder- controls buoyancy 

Sharks have a skeleton of cartilage instead of bone


Amphibians

  • First vertebrates to have both aquatic and terrestrial (land) adaptations 

  • Part of life in the water and part of its life on land

  • Evolved from fishes

  • Moist skin, require water for reproduction 

  • Has to have water for reproduction (similar to mosses and ferns) 

  • Specialized legs

  • Respiration (cutaneous, lungs)

Reptiles

Crocodile is a V

Alligator is a U

  • Characteristics fr life on land (prevent dehydration:

  • Dry skin, scales

  • Cold blooded (ectotherms) must use environment to control body temperature

  • Don't need water to reproduce or live in 

  • Ecto- outer

  • Four chambered heart (large and efficient) 

  • Respire only through lungs

  • Amniotic egg- watertight with 4 distinct membranes 

Amniotic egg(reptiles)

  • Oxygen goes in co2 goes out 

  • Leathery shell

  • Amniotic layer- chorion 

  • Yolk sac- food and nutrients for development

  • Allantois- for gas and liquid waste 

  • Amnion- surrounds baby 

Birds

Reptilian characteristics

  • One lineage of dinosaurs survives today as birds

  • Amniotic egg

  • Scales (but lack teeth)

-Most species are song birds

Archaeopteryx is an ancestor 

Feathers- modified scales

  • Some fly and some dont

  • Water 

  • s

Smallest bird ?bee hummingbird 

Largest bird ? ostrich 


Unique characteristics

  • Feathers (scales but lightweight) and probably evolved initially for insulation 

  • Flight skeleton: thin hollow bones

  • Some fused, anchor large breast muscles 

  • Tip of the v uses most energy 

  • Endothermic- generate metabolic heat for optimal, near constant body temperature

Mammals

  • Most terrestrial, some aquatic (share common ancestor with reptiles)

  • Dolphins, whales, corpus 

Characteristics

  • hair/fur ( warmth) 

  • Mammary glands- parental care (milk) 

  • Spend more time with their young (protected, fed, taught)

  • Specialized teeth 

  • Incisors

  • Amniotic tissues

  • Sweat glands

  • Yolk sac- important for early embryonic development

  • Allitos missing 

  • Waste in a mammal goes through the bloodstream

  • 5000 species of mammals 

  • Eutherians- 95% placentals

  • Marsupials- pouch

  • monotremes - lays eggs

  • Platypus and anteater lay eggs and produce milk 

Primates-The order of mammals that include humans

  • Grasping fingers and toes

  • Binocular vision- enhances depth perception 

  • Expanded brain

  • Complex social interaction 

  • Live in communities, groom each other, have a dominate male