Section 31.4 (Exam 3) Flashcards
Tetrapods Diversified Rapidly in Terrestrial Environments (64 cards)
What was necessary for the fish to evolve into land animals?
The ability to breath air; lung-like sacs (lungfishes)
What resulted in the ability to walk on land in lobe-limbed vertebrates?
paired pelvic and pectoral fins became more muscular, joined to the body by an enlarged bone
When were coelacanths thought to have become extinct?
65 mya
Where were living coelacanths found and when?
Off the coast of South Africa in 1938
What is a derived feature of coelacanths?
cartilaginous skeleton
Why is a cartilaginous skeleton a derived feature of coelacanths?
Because its ancestors had bony skeletons
What are some characteristics of lungfishes?
They have lungs and gills
They can burrow in mud when ponds dry up and survive many months in an inactive state while breathing air
What was the first step that aquatic lobe-limbed vertebrates took to evolve into ancestral tetrapods?
Using terrestrial food sources and became adapted to life on land
Which two groups make up tetrapods?
Amphibians and amniotes
What are some characteristics of amphibians?
Most remain tied to moist habitats; they lose water easily through the skin; eggs dry out if exposed to air.
Some species are entirely aquatic, and in others adults live on land, but must return to water to lay eggs; larvae develop in the water.
What are the three groups of amphibians?
Caecilians
Anurans
Salamanders
What are caecilians?
A major amphibian group
Wormlike, limbless, tropical burrowing animals
What are some characteristics of anurans, a major amphibian group?
Some have tough skins and other adaptations for dry habitats.
Many are arboreal; some completely aquatic.
All have a short vertical column and pelvic region modified for hopping/leaping or kicking in the water.
What are some characteristics of salamanders, a major amphibian group?
Many live in moist soil and rotting logs.
One major group has lost the lungs and relies on gas exchange through skin and mouth lining.
Completely aquatic species – they develop through neoteny.
What is neoteny?
retention of juvenile characteristics
Many amphibians have complex social behaviors. What are some examples of these?
Male anurans call to attract females and defend territories.
Some species lay a few eggs and guard the nest or carry the eggs on the body
What are some characteristics of amniotes that enable them to conserve water and exploit terrestrial habitats?
Amniote egg
Adult amniotes have a tough skin with scales, feathers, or hair to prevent drying.
Kidneys allow excretion of concentrated urine
How do kidneys in amniotes prevent water loss?
Kidneys allow excretion of concentrated urine, allowing excretion of nitrogen wastes without losing a lot of water
What are some characteristics of the amniote egg?
Relatively impermeable to water; the embryo develops in a contained aqueous environment
Leathery or brittle shells
Yolk
Extraembryonic membranes
What are some characteristics of the leathery/brittle shells of amniote eggs?
Retard water evaporation
Allow gas exchange
What is the function of a yolk in amniote eggs?
storing food
What is the function of extraembryonic membranes in the amniote egg?
protect the embryo from drying and assist gas exchange and excretion of nitrogen
Name some ways in which the amniote egg was modified for different organisms.
In several groups, modification of the egg allowed the embryo to develop inside its mother’s body
In mammals the egg lost its shell entirely; functions of the extraembryonic membranes were retained and expanded.
What are the two major groups of animals that amniotes split into?
Reptiles and mammals
