Lecture 17: Vertebrates Flashcards
(54 cards)
Vertebrates
- Development of a skeletal system and more complex nervous system
- Better ability to chase prey and run from predators
Most vertebrates have vertebrae that enclose the
spinal cord
* Replaces the mechanical roles of the notochord
Early-diverged vertebra traits
- No jaws
- Cartilage skeleton, composed of extracellular matrix proteins like collagen
- Cartilage can be mineralized with calcium for added support
Gnathostomes: Ancient Greek, gnathos-stoma, ‘jaw-mouth’
- Cartilage fish (sharks, rays, etc.)
- One of the biggest and most successful vertebrate predators in oceans
- Predominantly cartilage skeleton
- Limited use of mineralization may be a ‘derived trait’ for these species, as mineralization was present before they diverged from other vertebrates
Jaws
hinged structures that enable
animals to grip food items / slice them
Ray-finned fishes
- Fins are made of bony rays connected with webs without muscular structure
- Most of the extant ‘fish’ species are ray-finned
Lobe-fin fishes
- Pectoral and pelvic fins have a thick muscle
supporting the bony fin - Muscular fins can be used to walk on the bottom of the water
- Not a lot of extant species (with exception)
Ray-finned fishes and lobe-finned fishes skeleton and skeletal composition
Nearly all have ossified (bony) endoskeleton with a hard matrix of calcium phosphate
Three major groups of Lobe-fin fishes
Coelacanths
Lung fish
Tetrapods
Coelacanths definition
(pronounced SEE-le-kanth): The ‘living fossil’ that is believed to have remained unchanged from its ancestral shape for ~400 million years
Lung fish definition
Fish who has lungs as the means for gas exchange (in addition to gills)
Tetrapods definiton
Sister group of lung fish who adapted to life on land
* Muscular, pectoral and pelvic fins of lobe-fin fishes evolved into limbs with digits
Tetrapods structure and evolutionary timeline
- Tetrapods are Gnathostomes that have limbs with digits
- Greek,”four feet”
- Diverged about 365 million years ago
- Limbs support animal’s weight on land while digits efficiently transmit forces to the ground when walking
- Limbs changing into hands, wings and flippers
Amphibians
- Salamanders, frogs, caecilians
- Amphibian (‘both ways of life) refers to the dual life stages of frogs
- Tadpole: Aquatic larval stage, herbivore, legless, tail, gills
- Frog: Terrestrial adult stage, carnivore, legs, tailless, lungs
Many amphibians are strictly __ or __
aquatic, terrestrial
* Still need to inhabit moist habitat
* Major gas exchange through skin
* Lays egg in moist environment or in water; eggs are not well protected from desiccation
Amniotes
- Amniotes are tetrapods with terrestrially adapted eggs
- Reptiles and mammals
Amniotic egg contains
specialized membranes to nurture the embryo
* Amnion is the membrane that encloses the amniotic fluid which the embryo floats in
* Other membranes function in gas exchange, transfer of nutrients, waste storage
Amniotic egg allows terrestrial organisms to
nurture embryo without having access to a body of water
Reptiles
Turtles, tuataras, lizards, snakes, crocodilians, birds
Many reptiles such as lizards and snakes are
ectothermic
* ‘Cold blooded’
* Use the environment (sun/shade)to
regulate their body temperature
* Need tenth of the energy to survive compared to a mammal of the same size
Birds are
endothermic
* Uses metabolic activity to maintain body
temperature
* Less energy efficient but resilient to harsher environments
Mammals
Mammals are Amniotes that have hair and produce milk to nurture the young
Milk
balanced diet rich in fats, sugars, proteins, minerals and vitamins
* Produced in mammary glands
Mammals are __ with high metabolic rate
endothermic
* Hair and fat layer under the skin provides insulation