Exam 2 Flashcards
Bony Fish, Transition to Land
What are the general characteristics of Osteichthyes?
bony fish
- 1st appearance of the bony endoskeleton.
- swim bladder.
- terminal mouth.
- homocercal tail (=).
- paired fins.
- overlapping scales.
What type of bone do we see in bony fish?
- endochondrial bone = long bones, start out as cartillage.
- dermal bone = form as bone.
Ray-Finned Fishes
Actinopterygii
Lobe-Finned Fishes
Sarcopterygii
Neopterygii
modern ray-finned fishes.
What are the different anatomical features of ray-finned fishes?
compared to Chondricthyes
- pectoral fins moved up & along side of body.
- pelvic fins move forward.
- tail becomes homocercal (=)
- gill slits become opercular cover (pump water over gills).
- increase # of muscles (more movement).
- jaw now able to open extremely wide.
What are the different anatomical features of lobe-finned fishes?
- pectoral & pelvic fins similar to chondricthyes (more stability).
- bone projected into fins.
What is the main purpose of having scales?
- outside protection.
- osmoregulation (doesn’t allow diffusion to take place accross it).
- can age a fish by looking at rings (like trees).
What are the different scale types?
Placoid, Cosmoid, Ganoid, and Cycloid/Ctenoid scales.
Placoid Scales
- Chondrichthyes.
- tooth-like.
- have blood supply.
Cosmoid Scales
- adaptation of placoid scales.
- found in ancestral-type bony fish (ex. lungfish).
- very stiff (less flexible body).
Ganoid Scales
- rhomboid shape ♢.
- modified cosmoid scales.
articulating peg & socket joint btwn them.
Cycloid & Ctenoid Scales
- modern fishes.
- thinner, more flexible (more flexible body).
- cycloid = round edge.
- ctenoid = comb edge.
Can fish have multiple scale-types?
yes, they are usually found in different areas of the body.
What do some fish use in place of scales?
- thick layer of mucus.
- leathery skin.
- bony plates.
What are changes seen in Neopterygii?
modern day ray-finned fishes
- migration towards more mobile body types (lighter skeleton/scales)
- more powerful jaws (pharyngeal jaws).
- Weberian Apparatus.
Pharyngeal Jaws
tooth and tooth-like elements found inside skeletal support in mouth with additional teeth.
ray-finned fishes
- help grasp and orient prey.
- don’t chew!
Weberian Apparatus
a series of bones that sit againts the swim bladder that helps certain fish pick up vibrations from the environment.
- how they “hear”
What Period is “The Age of Fish”?
Devonian Period.
What is the main difference between ray-finned fishes and lobe-finned fishes?
ray-finned fishes fins have bony rays while lobe-finned fished have fins with true bone.
Anguillaform
the entire body moves in a wave-like motion.
eel-like
- slow swimmers
- length of body ↑ drag, ↓ thrust.
Carangiform
only 1/3-1/4 of the body flex for movement.
tuna-like
- fast swimmers
- ↑ thrust, ↓ drag
Ostraciform
body is completely rigid with movement coming from the caudal fin.
box-like
- slow swimmers
- ↑ drag.
Ballistiform
thrust from undulating the dorsal and anal fins.
Labriform
thrust from rowing the pectoral and pelvic fins.
Aspect Ratio
the ratio of the width to its height.
Why is aspect ratio important in Osteichthyes?
the higher the height of the tail, the lower the drag, and therefore less power is needed for movement.
What locomotive strategy has a high aspect ratio?
cruising (use the tail a lot).
What locomotive strategies have a low aspect ratio?
manueverability (pectoral/pelvic fins help sharp turns) and acceleration (rapid starts).
Why are Osteichthyes considered the most successful vertebrate group?
fish are found everywhere you can find water.
Why are Chondrichthyes considered the most successful vertebrate group?
they are at the top-level predators everywhere they are found.
What skeletal and anatomical features were necessary for the transition to land?
- pectoral girdle no longer fused, developement of cervical vertebrae (head moves more freely from the body).
- vertebrae overlap each other, adds support against gravity.
- change in head anatony/musculature for new feeding styles.
- swim bladder becomes lungs.
- limbs move under body, start to move more independently (more muscles).
- thicken and strengthen bones, more bones.
- more bone projections for muscle attatchement.
What are the basic differences between aquatic and land environments?
- gravity has more of an effect.
- more oxygen (plants).
- less water (easier to dessicate).
What are advantages of moving to land?
- new food resources = less competition.
- avoidance of predators (big dog now).
- more oxygen (less energy used to respire, easier to move in/out).
What are disadvantages of moving to land?
- gravity = need for new morphology (lots more E and nutrients needed).
- water becomes limited (must conserve, dessication a problem).
- rapid heat changes on land, hard to adjust to.
MORE ENERGY NEEDED TO MAINTAIN LIFE ON LAND!!!
- more energy → need more nutrients → need more food
Compact Bone
forms the outer shell of all bones and shafts in long bones.
Spongy Bone
at expanded heads of long bones and filling of most irregular bones.
What is the purpose of bone?
- provide support and movement via attatchements to muscle and soft tissue.
- protect vital organs.
- provide red marrow for the production of blood cells.
- metabolism of minerals (calcium and phosphates).
What is bone comprised of?
- 60% inorganic components (calcium phosphate).
- organic collagen.
Calcium Phosphate
inorganic component of bone.
- calcium is used to contract muscles.
- phosphorus provides energy to relax muscles.
What did the notochord turn into?
intervertebral discs.
Intramembranous Ossification
membrane bone/flat bone formation.
1. increase vacularity of tissue
2. rapid reproduction of mesenchymal cells → osteogenic cells → osteoblasts.
3. osteoblasts lay down osteoid (organic part of bone).
4. osteoblasts either retreat or become entrapped as osteocytes in osteoid.
5. osteoid calcifies (w/ hydroxyapitite crystals) to form spicules of sponge bone.
6. bone remodeling occurs, periosteum and compact bone formed.
CARTILLAGE NOT INVOLVED!!!!
What stays cartillagenous in endochondrial ossification?
epiphyseal plates (growth plate).
Endochondrial Ossification
bone deposited into pre-existing cartillage to form long bones.
1. first formed as cartillage.
2. primary center of ossification, in the bone shaft.
3. perichondrium → periosteum → osteoblasts.
4. osteoblasts lay down osteoid (organic part of bone).
5. calcification of matrix.
6. invasion of pereosteal bud → bone marrow.
7. formation of trabeculae (support tissue).
“REPLACEMENT BONE”
What are the 2 main types of vertebrate bone?
dermal and endochondrial.
What are shared ancestral characteristics of mammals?
vertebrae, paired appendages, and jaws.
What are shared derived characteristics of mammals?
mammary glands.
all respiratory systems function based on what?
diffusion.
List the periods in order from earliest to most recent:
Cambrian → Ordovician → Devonian → Carbiniferous → Cretaceous
List these key features in order of first appearance in vertebrate history:
- single set of hox genes.
- distinct cranium.
- paired appendages.
- endochonrial bone.
- amniotic egg.
What was the first animal to invade the terrestrial environment?
arthropods.
Why did vertebrates first evolve in the aquatic environment?
the T was too warm on land due to high amounts of CO2, water is more thermally stable so no chance of dessication.
