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What Phylum are humans in?
Chordata
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What are the 4 features that embryos (and often the adults) possess?
- - A dorsal, hollow nerve cord
- - A notochord
- - Pharyngeal slits
- - A muscular, post-anal tail
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What is a notochord?
A flexible, supportive, longitudinal rod
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Lancelets
The are small, blade-like chordates that live in marine sands
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Of the 1.7 million known organisms, how many are animals?
1.3 million
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What is a duck-billed platypus?
A monotreme, a small group of egg-laying mammals
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Vertebrates
Have a backbone
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Tetrapods
Have jaws and two pairs of limbs
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Amniotes
Terrestrially adapted eggs
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What are the most primitive vertebrates?
Hagfishes and lampreys
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Hagfishes
- The notochord is the body's main support in the adults
- - Craniate
- - Lacks paired fins and hinged jaws
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Lampreys
- –have a supportive notochord but also have rudimentary vertebral structures, making them vertebrates
- - Craniates
- - Lack a hinged jaw and paired fins
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Characteristics of Hagfishes
- - There are 40 species
- - Deep sea scavengers
- - They produce slime as an anti-predator defense
- - They are nearly blind but have excellent smell and touch
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Characteristics of Lampreys
- - They are parasites that penetrate the sides of fishes with rasping tongues
- - Larvae resemble lancelets
- - They are suspension feeders that live in fresh water streams, where they feed buried in sediment
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Where did jaws come from?
- They arose as modifications of skeletal supports of the anterior pharyngeal gill slits (originally used for trapping suspended food particles)
–The remaining gill slits remained as sites of gas exchange
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What are the three lineages of jawed fishes?
- – Class Chondrichthyes, which includes sharks and rays
- – Ray-finned fishes that have lungs (or lung derivatives)
- – Lobe-finned fishes that have lungs (or lung derivatives) and muscular fins supported by stout bones.
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Characteristics of Chondrichtyes (Sharks and Rays)
- - Sharks and rays have a flexible skeleton made of cartilage
- - Most sharks are fast-swimming predators, with sharp vision and a keen sense of smell
- - Electrosensors on their heads and a lateral line system aid them in locating prey
- - Most rays are adapted for life on the bottom, with dorsoventrally flattened bodies and eyes on the top of their heads
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Types of Ray-Finned fishes
Tuna and Trout
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Characteristics of ray-finned fishes
- - Internal skeleton reinforced with a hard matrix of calcium phosphate (CaPO3)
- - Flattened scales covered with mucus
- - Operculum to move water over the gills
- - A buoyant swim bladder (derived from an ancestral lung)
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How many species of ray-finned fishes are there?
- 27,000
- - The greatest number of species of any vertebrate group
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Characteristics of lobe-finned fishes
- Lobe-fins have muscular pelvic and pectoral fins, supported by rod-shaped bones
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What are the three lineages of lobe-fins?
- - Coelacanths
- - Lungfishes
- - Tetrapods
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What are tetrapods?
Jawed vertebrates with limbs and feet
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Amphibians
- - Includes frogs, salamanders, and caecilians
- - Most have tadpole larvae
- - They were the first tetrapods to be able to move on land (but some are still entirely aquatic)
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Salamanders
- - Most live on land
- - They walk with a side-to-side bending of the body
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Frogs
- More developed for moving on land with powerful hind legs
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Caecilians
- - Blind, limbless and they burrow in soil
- - Mainly live in tropical areas
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Where are most amphibians found?
- - In damp habitats
- - Moist skin supplements lungs for gas exchange
- - Many of them have poison glands for defense
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Amniotes
Reptiles, birds, and mammals
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Amnion
A private pond in which the embryo develops
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Types of amniotic reptiles
Snakes, lizards, turtles, crocodilians, and birds
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Lizards
Most diverse of the reptiles
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Snakes
- Closely related to lizards
- Limbless due to ancestors burrowing lifestyles
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Turtles
- Haven't changed much over time
- Uncertain of ancestral lineage
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Crocodilians
- Crocodiles and alligators
- They are the largest living reptiles
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What are the important roles or essential services of birds?
Pollinate flower, disperse seeds, and consume insects
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Basic characteristics of birds
- Bipedal (2-legged) vertebrates
- Have a backbone
- Feathers
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What is the purpose of feathers for birds?
- Flight
- Essential for temperature regulation
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Characteristics of bird feet and perching
- Their feet grip tightly
- The tendons automatically flex when the bird squats on a branch
- The toes lock around the branches
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Bird Eggs
- Richly provisioned external eggs
- No species bear live young
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Bird Brains
- Large and well-developed (6 - 11 times the size of comparable reptiles)
- Neural system is highly developed
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How many birds are on earth?
~300 billion birds on Earth
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Current classification for birds
- 30 Orders
- 193 Families
- 2099 genera
- About 9700 species
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What is variety and diversity of birds based off of?
- Adaptive Radiation
- Evolutionary change and adaptation
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Adaptive Radiation
The evolution of additional varied species adapted to different ecologies and behaviors
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How are birds diversified?
- Bill size and shape changes due to the type of food eaten
- Leg length changes in relation to perching and terrestrial locomotion
- Wing shape changes due to different patterns of flight
- Seasonal and social behavior (reproductive rate, life span, age of maturity, etc.)
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Albatrosses
- One egg at a time
- Very long life span
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Songbirds
- Very short lifespan
- Large clutch sizes
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When does Avian history start?
More than 150 million years ago
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What major extinctions was Class Aves in?
- Late Cretaceous
- Beginning of the Pleistocene about 3 mya (about 25% of bird population lost)
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Similarities between birds and reptiles
- Similar leg structure
- Scales
- In both, females are the heterogametic sex
- Nucleated red blood cells
- Original link - Archaeopteryx
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Archaeopteryx
- Fine-grained limestone
- From late Jurassic (155-135 mya)
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Characteristics of Archaeopteryx
- There are now 7 specimens
- Crow-sized, bipedal ‘reptile’ with scales
- Blunt snout, many small teeth
- Feathers on wings and tail (probably entire body as well)
- Capable of gliding, weak flapping
- Feather veins were asymmetric (indication of flight)
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Mammals
- Endothermic amniotes
- Have hair, which insulates the body
- Have mammary glands, which produce milk
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When did the first true mammals arive?
200 million years ago as nocturnal insectivores
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What are the three main groups of mammals?
- Marsupials
- Monotremes
- Euterians (placental mammals)
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When did marsupials diverge from euterians?
180 mya
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What are the oldest lineages of monotremes?
- Duck-billed platypus
- Ecidna
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Embryos of marsupials and eutherians
- The embryos of marsupials and eutherians are nurtured by a placenta within the uterus
- The placenta allows nutrients from the mother’s blood to diffuse into the embryo’s blood
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Only North American marsupial
Virginia Oppossum
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Eutherian reproduction
- They are commonly called placental mammals, because their placentas are more complex than those of marsupials
- Young complete development within mother
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