Bio Sci 2 Exam 2
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What Phylum are humans in?
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
What is a notochord?
A flexible, supportive, longitudinal rod
The are small, blade-like chordates that live in marine sands
Of the 1.7 million known organisms, how many are animals?
What is a duck-billed platypus?
A monotreme, a small group of egg-laying mammals
Have a backbone
Have jaws and two pairs of limbs
Terrestrially adapted eggs
What are the most primitive vertebrates?
Hagfishes and lampreys
- The notochord is the body's main support in the adults
- - Craniate
- - Lacks paired fins and hinged jaws
- –have a supportive notochord but also have rudimentary vertebral structures, making them vertebrates
- - Craniates
- - Lack a hinged jaw and paired fins
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
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
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
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.
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
Types of Ray-Finned fishes
Tuna and Trout
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)
How many species of ray-finned fishes are there?
- - The greatest number of species of any vertebrate group
Characteristics of lobe-finned fishes
- Lobe-fins have muscular pelvic and pectoral fins, supported by rod-shaped bones
What are the three lineages of lobe-fins?
- - Coelacanths
- - Lungfishes
- - Tetrapods
What are tetrapods?
Jawed vertebrates with limbs and feet
- - 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)
- - Most live on land
- - They walk with a side-to-side bending of the body
- More developed for moving on land with powerful hind legs
- - Blind, limbless and they burrow in soil
- - Mainly live in tropical areas
Where are most amphibians found?
- - In damp habitats
- - Moist skin supplements lungs for gas exchange
- - Many of them have poison glands for defense
Reptiles, birds, and mammals
A private pond in which the embryo develops
Types of amniotic reptiles
Snakes, lizards, turtles, crocodilians, and birds
Most diverse of the reptiles
- Closely related to lizards
- Limbless due to ancestors burrowing lifestyles
- Haven't changed much over time
- Uncertain of ancestral lineage
- Crocodiles and alligators
- They are the largest living reptiles
What are the important roles or essential services of birds?
Pollinate flower, disperse seeds, and consume insects
Basic characteristics of birds
- Bipedal (2-legged) vertebrates
- Have a backbone
What is the purpose of feathers for birds?
- Essential for temperature regulation
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
- Richly provisioned external eggs
- No species bear live young
- Large and well-developed (6 - 11 times the size of comparable reptiles)
- Neural system is highly developed
How many birds are on earth?
~300 billion birds on Earth
Current classification for birds
- 30 Orders
- 193 Families
- 2099 genera
- About 9700 species
What is variety and diversity of birds based off of?
- Adaptive Radiation
- Evolutionary change and adaptation
The evolution of additional varied species adapted to different ecologies and behaviors
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.)
- One egg at a time
- Very long life span
- Very short lifespan
- Large clutch sizes
When does Avian history start?
More than 150 million years ago
What major extinctions was Class Aves in?
- Late Cretaceous
- Beginning of the Pleistocene about 3 mya (about 25% of bird population lost)
Similarities between birds and reptiles
- Similar leg structure
- In both, females are the heterogametic sex
- Nucleated red blood cells
- Original link - Archaeopteryx
- Fine-grained limestone
- From late Jurassic (155-135 mya)
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)
- Endothermic amniotes
- Have hair, which insulates the body
- Have mammary glands, which produce milk
When did the first true mammals arive?
200 million years ago as nocturnal insectivores
What are the three main groups of mammals?
- Euterians (placental mammals)
When did marsupials diverge from euterians?
What are the oldest lineages of monotremes?
- Duck-billed platypus
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
Only North American marsupial
- 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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