vertabrates Flashcards
(23 cards)
Which animals are classified as vertebrates?
Vertebrates include hagfish, lampreys, sharks and rays, bony fishes, amphibians, mammals, and reptiles (including birds).
What do the pharyngeal pouches develop into in aquatic species?
Gills.
What does the notochord become in vertebrates?
The vertebral column.
What does the dorsal hollow nerve cord develop into?
The spinal cord.
What is the function of the vertebral column?
Body support and movement.
What are somites?
Segmented blocks of tissue that later differentiate into vertebrae, ribs, and skeletal muscles.
What are the two synapomorphies that distinguish vertebrates?
- A column of cartilaginous or bony structures called vertebrae
- A cranium that encloses the brain.
What is the role of the vertebrae and cranium in vertebrates?
They protect the central nervous system and key sensory structures.
How is the vertebrate brain organized?
Divided into three distinct regions: forebrain, midbrain, and hindbrain.
What does the forebrain house?
The sense of smell.
What does the midbrain associate with?
Vision.
What is the hindbrain responsible for?
Balance and hearing.
What did the earliest vertebrates resemble?
Streamlined, fishlike bodies with gills, a notochord, post-anal tail, and paired eyes.
Where were the earliest vertebrate fossils found?
Chengjiang formation of China and Burgess Shale in Canada.
What is the hagfish hypothesis for early vertebrates?
- Hagfishes and lampreys have a notochord
- Gills
- A muscular post-anal tail
- A three-part brain
- Paired eyes
- Cartilaginous cranium.
What are the four major living lineages of jawed fishes?
- Cartilaginous fishes (Chondrichthyes)
- Ray-finned fishes (Osteichthyes)
- Coelacanths
- Lungfishes.
What is the significance of jaws in vertebrates?
They improved the ability of fishes to capture and kill prey.
What is the gill-arch hypothesis?
Proposes that natural selection acted on developmental regulatory genes to produce the first working jaw.
What modifications occurred to jaws in ray-finned fishes?
- Jaws are protrusible
- Some lineages have a second specialized jaw called a pharyngeal jaw.
What is the origin of the bony endoskeleton?
It began to be stiffened by deposition of bone in some lineages of fishes from late in the Silurian period.
What is bone made of?
Calcium phosphate.
True or False: Cartilage is heavier and more rigid than bone.
False.
Fill in the blank: The notochord helps organize the body plan early in development by secreting _______.
[proteins that induce somite formation].
