ZOO*2090 - Lecture Flashcards
When was the Early Cambrian?
Around 540 million years ago.
When was the Middle Cambrian era?
Around 520 million years ago.
Give 3 ways the origin of vertebrates can be studied.
- The fossil record ( most direct but a fossilization is a rare event).
- Phylogenetic approach (determine common ancestry).
- Evolutionary developmental biology.
About what time did the earliest vertebrates arise?
Around the same time as the first chordates ( early Cambrian).
In what subphylum are Amphioxus?
Subphylum Cephalochordata (branchiostomata).
In what subphylum are Tunicates?
Subphylum Urochordata.
What is the difference between “Craniata” and Vertebrata?
Craniata is an unranked taxon that included vertebrates and hagfish (even though hagfish only have rudimentary vertebrae, not real vertebrae).
What are the 5 major innovations of the vertebrates?
- Vertebral column
- Head: cranium & brain
- Jaws
- Paired Limbs
- Cleidoic egg
*note: not all species have #3-5, and all innovations are derived.
Label the parts of a vertebral column.
Neural spine, Neural arch, Centrum, Hemal arch, Hemal spine, Intervertebral body, Dorsal hollow nerve cord, blood vessel.
Why is it significant to have a vertebral column?
- Support,
- Protection,
- Muscle attachment/ locomotion
How does the neural tube form?
Migrating neural crest cells push dorsal edges of neural plate together to form a tube.
What is the significance of a head?
- Houses brain
- Allows for brain expansion
- Provides protection
What are Agnatha?
Class. Jawless fishes
ex. hagfishes and lampreys
Describe the evolution of jaws in 3 steps.
- Invertebrates –> used suspension feeding (cilia); ineffective because passive
- Agnatha –> muscular pharyngeal pump made suspension feeding more active + evolution of gills
- Gnathastomes –> evolved jaws and muscular mouth to grab & “chew” food.
What is the significance of limbs?
They allow for better movement.
What is the significance of a cleidoic egg?
- Allows eggs to sit outside of water
- Provides protection outside of water
*Note: to produce hard shells, it took the evolution of many different membranes.
What are tetrapods? Give examples.
Tetrapods –> animals out of water, with limbs.
ex. amphibians (frogs, salamanders), reptilians (snakes, lizards), birds, mammals.
What are Chondrichthyes?
Class. Have jaws.
ex. sharks and rays
What is “Osteichthyes”?
Class. Have jaws.
ex. bony fishes
What is Amphibia?
Class. Have jaws. Tetrapods.
ex. frogs and salamanders
What is Reptilia?
Class. Have jaws. Tetrapods.
ex. snakes, lizards, turtles
What is Aves?
Class. have jaws. tetrapods.
ex. birds
What is Mammalia?
Class. Have jaws. Tetrapods.
ex. mammals
How is diversity made? (aka what are the 3 processes of development).
- Cleavage –> from zygote to multicellular hollow blastula
- Gastrulation & neurulation –> cell movement (formation of multilayer structure)
- Differentiation & organogenesis –> from cell layers to organs
What are Cyclostomes?
An eel-like jawless vertebrate with a round sucking mouth.
Hagfishes and Lamprey (agnatha)
What are Conodonts & Ostracoderms?
Extinct groups of agnatha.
What is the economic significance of lampreys being parasitic?
Lampreys invade the Great Lakes and kill off many large lake trout, which causes populations to crash.
What kind of system did conodonts use to feed?
Conodonts use a pully system to feed.
S&M elements latch on to prey.
P elements grind up food.
What are the 3 main groups under Gnathostomes?
- Placodermi
- Chondrichthyes
- Osteichthyes
How do hagfishes eat?
They use cartilaginous plates (like teeth) that help with food consumption.
Similar to lamprey, hagfish have a single nostril on top of their head. True or False?
True.
Hagfishes have cartilaginous skulls and a full vertebrae. True or False?
False.
Hagfish have cartilaginous skulls but only rudimentary vertebrae.
Give 3 characteristics of Lampreys.
- Marine or freshwater
- Complex development –>metamorphosis of ammoecete larva into adult form
- Cartilagenous skull and vertebrae
- No jaws, single nostril, has fins (dorsal, unpaired)
Lamprey have image forming eyes. True or False?
True.
Ostracoderms are very diverse. True or False?
True.
Give 3 characteristics of Ostracoderms.
- Small and Jawless
- Have lateral line system
- Outer exoskeleton of dermal bone plates
Approximately when did the jaw evolve?
Around the Devonian (390mya).
From where did the jaw evolve? What is each element of the jaw called?
Jaws evolved from first branchial arch.
- Upper element = palatoquadrate
- Lower element = Meckel’s cartilage
What is the significance of the evolution of jaws?
- Enabled new diets and food handling techniques.
- Expanded predatory lifestyle)
(firm grip on prey, manipulation, cutting and grinding, suction feeding)
What are some alternate ideas concerning the evolution of the respiratory muscles?
Inhalation muscles evolved to ensure active respiration (ventilatory jaws).
Before: muscles encircled the pharynx –> Passive inhalation
After: addition of inhalation muscles made branchial arches more robust –> Active breathing
Give 3 characteristics of Placodermi.
- Diverse marine group
- Heavy head, thoracic armour and naked body
- Jaws with beak-like plates
- Paired pectoral and pelvic fins
- Varied feeding styles
- Dominated Devonian, disappeared quickly from fossil record
How did Placodermi eat?
- Sucked from the ocean floor
- Was a predator (attacked) and was protected by its armor.
Give 3 characteristics of Chondrichthyes.
- Cartilaginous fishes –> calcified skeleton
- Placoid scales (bony base with dentine)
- Internal fertilization
- Presence of spiracle (allows water to drain from above the organism)
-Extensive radiation after decline of placoderms
What are the two main types of Chondrichthyes?
- Chimaeras (40spp)
- Elasmobranchs –> Sharks (360spp), Rays and skates (>500spp)
The jaws of sharks are attached to their skulls. True or False?
False. Jaws are not attached to skull.
Sharks have swim bladders. True or False?
False.
No swim bladder –>use liver and motion (lift) to stay buoyant.
Give 3 characteristics about stingrays, electric rays and skates.
- Flattened body
- Pectoral fins modified to become wing-like appendages for swimming
- Live on ocean floor.
Bony fishes are also called _______.
Bony fishes are also called Osteichthyes.
What are the two main groups of Osteichthyes?
- Actinopterygii (ray fins)
- Sarcopterygii (lobe fins)
What are the most diversified group of vertebrates?
Actinopterygii.
What kind of animals are considered Acinopterygii?
- Sturgeons and paddlefishes (35spp)
- Garpikes
- Bowfins (8 sppt ogether)
- Teleosts
Teleosts are incredibly diverse. True or False?
True.
Where did teleosts evolve and what were two specializations that are considered important to them?
-Likely evolved in sea and radiated into freshwater
- Swim bladder, specialization of swimming mode
- Specialization of jaw played major role in diversification
What are some teleost families?
- Carps and minnows
- Gobies
- Salmon, trout, and charr
- Perch and relatives
What are two living groups of Sarcopterygii?
- Dipnoi (lungfishes)
- Coelancanth
What are characteristics of lobe-fin appendages?
- Internal bones and muscles
- Fins have rays at the end
What is the function of the paired lungs in a lungfish?
Acts as a modified swim bladder.
How do lungfishes estivate “dry sleep”?
- Burrow into river bed during dry season
- Create mucous cocoon which hardens
- Emerge when rain starts
Coelacanth have changed a lot from their ancestors. True or False?
False. They are relatively unchanged from their ancestors.
_______ is thought to be closely related to the ancestor of tetrapods.
Rhipidistia is thought to be closely related to the ancestor of tetrapods.
When did Tiktaalik exist and why are they important?
-Late Devonian (375 Mya) fish found on Ellesmere Island (2004).
Shows intermediate characteristics between fish and tetrapods.
What was the importance of the Devonian?
Jawless fish, placoderms, sharks, ray-finned fish, tetrapods
- Jawless fishes are prominent at beginning, decrease near end
- Placoderms start getting important
- Sharks begin getting prominant (so much that placoderms go extinct)
- Birth of ray-finned fishes
- Tetrapods only became more evolved when other groups declined.
What is the skeleton composed of?
- Bone,
- cartilage,
- ligaments
- tendons
What are the functions of the skeleton?
- Supports weight and protects soft parts
- Anchors muscles for movement
- Stores minerals, particularly calcium
What are the main components of the skeleton?
- Head skeleton or skull (cranium)
- Axial skeleton: vertebral column, ribs and sternum
- Appendicular skeleton: girdles and fins/limbs
What are the components of the skull?
*Hint: 3 components
1) Chondrocranium(neurocranium)
2) Splanchnocranium(visceral cranium)
3) Dermatocranium
Agnathan skulls fall into 2 categories. What are they? How do they differ
- Species without armor
- Have: Chondrocranium, Splanchnocranium, No dermatocranium
- Cartilage provides support because there is no jaw - Ostrachoderms with armor
- Has all 3 components of skull
- Has mandibular arch (becomes jaw later)
- Has hyoid arch and rest of branchial arches.
Why are placoderms important?
Placoderms are important because they are the first group to get jaws.
What are two features of Placoderm skulls.
- Presence of jaws (Meckel’s cartilage and palatoquadrate)
2. Well developed dermatocranium (in addition to well developed other two components)
Teleost skulls are all homologous. True or False.
True.
Teleost skulls have increased number of bones with reduced connections. What is the advantage of this?
- Allowed for more space in skull
- Increased maneuverability in jaws
Teleosts have all three components of the skull with a prominent neurocranium. True or False?
False. Teleost skull often has a small neurocranium ( chrondrocranium).
Describe some differences between the skull of early gnathostomes and teleosts.
Early gnathostomes:
- Wide mouths
- Hinge was far back
- Upper jaw fused with brain case
Teleosts:
- Narrow mouth
- Hinge moved forward
- Upper and lower jaws can move independently of braincase (importance of maxilla and premaxilla)
How is suction driven by volume charge of orobranchial chamber?
- Independent bones and change in space in cavity leads to a pressure change (forces water inside of mouth)
- Muscles on bottom of mouth pulls, so volume increases
- This is an effective way to get material into mouth
- Know: Maxilla, premaxilla, hyoid apparatus.
What are the different kinds of jaw suspensions?
Hint: 3
- Autostylic: upper jaw braced against braincase, no hyomandibula role (placoderms, lungfishes)
- Amphistylic: hyomandibulabone (second arch) acts as a strut to help brace jaw along withbrain case (some sharks and bony fishes; coelacant)
- Hyostylic: mandibular arch supported primarily by hyomandibula (most bony fish and shark)
What is the functional significance of hyostyly?
Hyostyly allows more movement and mobility of jaws. Modified hyostyly (teleosts) have jaws that are more forward.
What are the components of the Axial skeleton?
- Centrum: body
- Neural arch: protects spinal cord
- Hemalarch: protect blood vessels (only tail vertebrae)
- Processes (apophyses)
What is the role of the notochord?
- supports vertebral elements in early fishes
* Note: Vertebrae surround notochord in most bony fishes
What allows teleosts to have greater flexibility?
- Notochord is greatly reduced to resit buckling
- Ligaments keep vertebrae together
Give 3 characteristics of fish axial skeleton.
-Fixed link between the first vertebra and the skull
-Amphicoelous centra
(concave at both ends), and no zygapophyses (interlocking processes)
-Regional differentiation –> only trunk and caudal region(with hemalarch)
-Notochord remains throughout life in some, replaced by centra in others
-Movement by lateral undulation
What are the parts of the appendicular skeleton?
- Appendages: paired fins or limbs
- Girdles: braces that support paired appendages
What are the types of fins and what are their functions? (3)
- Paired fins –> Stability, fine control when mobile
- Median fins –> keep body from rolling
- Caudal fin –> add to propulsion in lateral undulation locomotion
What are the three types of paired fins and in what animals are they found?
- Lobe fins: fleshy (lungfishes)
- Fin-fold fins: broad base (cartilaginous fishes)
- Ray fins: (most bony fishes)
How are membranes of fins strengthened in fish?
- Membranes strengthened by bones (pterygiophores) and flexible rays
- Rigid spines can also be present
How do fins vary between Elasmobranchs and bony fishes?
Elasmobranchs –keratinized rods (ceratotrichia)
Bony fishes –bone/cartilage elements (lepidotrichia) and keratinized tips (actinotrichia)
What did the pectoral girdle evolve from sharks to teleosts? What is the advantage?
Sharks: Right and left halves fused in midline (Not jointed to skull)
Teleosts: Pectoral girdle joined to skull via cleithrum bones (gave more strength)
The pelvic girdle is very complex. True or False.
False. The pelvic girdle is relatively simple.
The pelvic girdle is made up of 3 plates, fused mid-ventrally to form a pelvic symphysis. True or False?
False. The pelvic girdle is made up of two plates sometimes fused mid-ventrally to form a pelvic symphysis.
What is Integument?
It is the skin.
What is the basic structure of integument and what is its development?
Outside –> inside:
- Epidermis
- Dermis
- Hypodermis (may or may not be present)
Development:
Ectoderm –> epidermis
Mesoderm –> dermis
Neural crest –> pigment cells
What are the layers of the epidermis and what are their functions?
Outside –> inside:
- Stratum corneum –> keratinized for water proofing
- Stratum granulosum –> receives pushed up cells from inside layer (may contain single or multicellular glands)
- Stratum germativum –> makes new cells
What are the two layers of the dermis? What do they contain?
Outside –> Inside
- Vascular stratum spongiosum –> pigment cells or chromophores
- Thicker stratum compactum –> lots of fibers
What are two things the dermis often includes?
- A network of fibres (collagenous and elastic) for strength
- Small nerves, blood vessels
- Connective tissue to hold everything together
Where is the hypodermis located? What does it contain?
Hypodermis is located beneath the dermis.
It often contains fat cells for insulation and energy storage.
What are 4 functions of integument?
- Physical barrier –> protects against injury, pathogens, desiccation
- Respiration, excretion (CO2, urea), osmotic regulation
- Thermoregulation (on land)
- Colours and odours used in courtship or defense
- Locomotion
How does integument vary between vertebrates?
- Number and complexity of glands
- Differentiation of the stratum corneum
- Extent of bone development in the dermis (scales)
What are some functions of mucus in integument?
- Prevents entry of foreign materials
- Reduces drag
- May include substances toxic to predators
What is the function of the stratum corneum?
What are some of its derivatives?
Primary function is to provide protection against desiccation.
Derivatives:
scales, feathers, hair, claws, (keratin-based)
Fish have a lot of keratin in their epidermis. True or False?
False. Fish have none or little keratin in epidermis.
*Exception is “teeth” on lamprey oral disk or belly of semi-terrestrial fishes
Give 3 characteristics of fish scales.
Fish scales (many kinds):
- Made up of bone covered by the thin epidermis
- Sometimes coated with hard enamel (from epidermis)
- Deeper layer of dentin (from dermis)
•Ancient fishes had dermal scales and armor
Teeth of modern tetrapods are derived from ancient fish scales. True or False?
True.
What are the 4 different kinds of scales?
- Placoid scales (sharks and rays)
- Elasmoid scales (teleosts)
- Ganoid scales (sturgeons, paddlefishes, gars, bowfin)
- Cosmoid scale (ancient fishes)
Give 2 characteristics of Placoid scales.
- Also called dermal denticles
- Protrude through epidermis
- Organize water flow on skin to reduce drag (scales oriented posteriorly)
- Found in cartilagenousfishes (sharks and rays) so no bone
Give 4 characteristics of ganoid scales.
- Thick coat of enamel
- Dentin and vascular bone is lost
- Thick layer of lamellar bone
- Entire structure covered by thin epidermis
- Found in sturgeons, paddlefish, garpikes, bowfins
What are the two types of elasmoid scales?
- cycloid
- ctenoid (projections on posterior margin)
Give 3 characteristics of elasmoid scales.
- Found in teleosts
- Loss of enamel
- Made up of lamellar bone (relatively thin)
- Intermediate types exist
Elasmoid scales can be modified into plates. True or False?
True.
e.g seahorses.
Gas exchange follows physical rules of _____.
Gas exchange follows physical rules of diffusion.
What are 3 conditions needed for diffusion?
- Large surface between environment medium and blood
- Thin barrier
- Effective ventilation (gradient)
From where do the gas bladder and lungs develop?
- Develop from out pocketings of pharynx
- Endodermal in origin
What is a gas bladder and what is it used for?
-Single elongated sac that is dorsal to the gut.
- Used for buoyancy –control position in water column
- Can also be used for respiration (respiratory gas bladder) as well as sound production and reception
Where are lungs often located in regard to the gut?
Lungs are often located ventral to the gut.
Which is more efficient? Unidirectional or Bidirectional respiration?
Unidirectional.
The vertebrate circulatory system is extremely adaptable. True or False? Explain.
True. It has a capacity for repair, compensation for damage, and quick response.
What are the general components of the Cardiovascular system?
- Heart
- Blood vessels (arteries, veins, capillaries)
- Blood
*Note: the lymphatic system is associated with the cardiovascular system.
What are the 4 chambers in a fish heart? What kind of circuit pump is it?
- sinus venosus
- Atrium
- Ventricle
- Conus arteriosus
It is a single-circuit pump (pumps deoxygenated blood in one direction).
Compare the hearts of cartilaginous fishes and teleosts.
Cartilaginous fishes:
-large conus arteriosus, muscular and active as pumping organ
Teleosts:
- highly elastic bulbus arteriosus in place of conus
- Keeps consistent flow to arches despite pressure generated by beating heart
When did major events in vertebrate evolution occur?
Major events in vertebrate evolution occurred in the Devonian.
What were some challenges early vertebrates faced when transitioning from water to land?
- Movement
- Respiration
- Sensing the environment
- Feeding, osmoregulation and reproduction
What is a tetrapod?
Vertebrates that possess a chiridium–> muscular limb with well-defined joints and digits
What are some important characteristics of early tetrapods (Tiktaalik)?
Have:
- Limb-like pectoral fins –> support while standing
- Functional wrist joint
- Mobile neck allowing head movement
- No bony gill covering suggesting increased use of lungs for respiration
When did the Acanthostega live?
Hint: early tetrapod
Acanthostega lived in the late Devonian (Greenland).
What is a major characteristic of Acanthostega?
Acanthostega limbs have digits (8 fingers, 8 toes).
Also:
- Girdles are designed to bear weight
- Tail with fin rays and internal gills suggest it was aquatic
- ARM in glenoid, LEG in acetabulum
What is a major characteristic of Ichthyostega?
Ichthyostega lacked internal gills.
More:
- Late Devonian (Greenland)
- Similar to Acanthostega, although more robust
What are Temnospondyls? Give 2 characteristics.
Temnospondyls are a large group of extinct tetrapods.
- Considered to have given rise to modern amphibians.
- Main part of trunk is off the ground.
- Robust bodies and flat skulls
- Occupied a wide range of ecological niches
- Some capable of excursions or life on land
______ are considered to have given rise to modern amphibians.
Temnospondyls are considered to have given rise to modern amphibians.
Lepospondyls are large living tetrapods. True or False?
False. Lepospondyls are diverse small tetrapods that are extinct.
What two specialized ecological niches did Lepospondyls occupy?
- Eel/snake-like forms –> aquatic
- Lizard/newt-like –> more terrestrial
What animals were originally hypothesized to give rise to modern amphibians?
Originally it was thought that Lepospondyls gave rise to modern amphibians, but this is no longer supported. It is now considered that Temnospondyls gave rise to modern amphibians.
What are the 7 main structural changes that occurred from fish to tetrapods?
- Fin –> Chiridium
- Fused shoulder: Evolution of true neck
- Reinforced vertebral column and girdles
- Back part of skull is shortened and hyomandibula is no longer attached to otic capsule
- snout elongates and eyes move to top of head.
- Reduction in skull bones
- Modification of dermal scales of fish into scutes or gastralia: cover only belly in tetrapods.
Under what class does Chordata fall?
Hint: Kingdom, Phylum, Subphylum, Class, Order
Chordata is a Phylum.
What Phylums are close relatives to Chordata?
Phylum Hemichordata (acorn worms), & Phylum Echinodermata (star fish)
Chordata, Hemichordata and Echinodermata are all considered to be ________.
Chordata, Hemichordata and Echinodermata are all considered to be Deuterostoma.
What is the difference between Deuterostoma and Protostoma?
Deuterostoma and Protostoma differ in embryological development.
Phylum Hemichordata (acorn worms) are considered closely related to chordates because they share a trait. What is this trait?
Hemichordates and chordates both have pharyngeal slits.
Echinoderms are marine deuterostomes with ______ symmetry as adults, and ______ symmetry as larvae.
Echinoderms are marine deuterostomes with radial symmetry as adults, and bilateral symmetry as larvae.
What are the subphyla that compose the phylum chordata? (3)
Which ones are more closely related?
- Subphylum Urochordata
- Subphylum Cephalochordata
- Subphylum Vertebrata
Vertebrata and Urochordata share the most recent common ancestor.
What are the 5 characters that all chordates MUST have?
- Notochord
- Dorsal, hollow nerve cord
- Pharynx with pouches or slits in lateral walls
- Postanal tail
- Endostyle or thyroid gland
Cosmoid –> Elasmoid scales. What was lost/ gained?
Loss of:
- Dentin,
- Vascular bone
- Enamel
Cosmoid –> Ganoid scales. What was lost/ gained?
Loss of:
- Dentin,
- Vascular bone
Cosmoid –> Placoid scales. What was lost/ gained?
Nothing was lost or gained. Very similar composition, just different structure.
In fishes, the respiratory and circulatory system work together. True or False?
True.
What are 3 aspects of fish gills which allow for proper gas exchange in water?
- Large surface area (gills)
- Counter current exchange
- Thin blood-to-water barrier
What are the 3 types of internal gills?
Hint: Lampreys, sharks, teleosts
- Pouched gills of lamprey
- Septal gills of sharks
- Opercular gill of teleosts (has gill bar)
What are the 2 gill evolution trends?
- Reduction of number of gill bars & chambers.
2. Loss of spiracle and loss of septa.
What is the most common type of gill ventilation?
Dual pump.
What are the 3 types of gill ventilation?
Hint: Lamprey, active fish, most common
- Tidal ventilation (compression/ expansion of branchial cavity) –> lamprey
- Ram ventilation (keep mouth open when swimming) –> active fish
- Dual pump –> most common
Describe the two phases of dual pump ventilation.
- Suction pump phase
- Buccal cavity gets bigger,
- negative pressure encourages water to come into mouth
- opercular valve is still closed - Pressure pump phase
- Mouth closes
- Muscles contract to create positive pressure and push water out
- Valves open and water moves out over respiratory surface
What are the two methods gas bladders get filled?
- Physostomous–> filled by gulping air, comes through pneumatic duct.
- Physoclistous–> gas is forced from artery into bladder, exits through oval window (pushed by sphincter)
What happened to the first visceral arch?
It became a jaw.
What is the blood flow for actinopterygii?
Deoxygenated blood in heart –> ventral aorta –> aortic arches –> respiratory surfaces (gill pouches) –> oxygenated blood –> dorsal aorta –> rest of body –> heart
Why is it important that lungfish have a septum dividing their atrium and ventricle?
How does this division extend in the conus?
It is important because it allows for two streams of blood in the heart (oxygenated and deoxygenated).
Division extends to the conus because it continues into a spiral fold valve.
What are the left and right side of lungfish heart responsible for?
Left side = oxygenated blood
Right side= deoxygenated blood
What is the hypothesis of who gave rise to modern amphibians?
Most recent hypothesis: Temnospondyls arose later but lasted longer
Before: Lepidospondyls arose earlier, but didn’t last long
What was found in the experiment with amphibious fish (polypterus senegalus) called water to land?
Bichir became more efficient at terrestrial locomotion.
They had a larger clavicle, because physical activity of being on land increased size of bone.
How did early tetrapods move?
First tetrapods: limbs and girdles were too small and poorly ossified for walking on land
-Limbs likely used as points of pivot –> supported lateral flexions of the body in shallow water (like lobe-finned fishes)
How did more developed tetrapods move?
- Limbs and girdles of adults are massive and extensively ossified suggesting terrestrial habitat.
- Moved from side to side
What is the function of the notochord?
- Keeps the body straight and prevents collapse during muscle contraction
- Promotes or organizes embryological development of nearby structure
How is the hollow nerve cord formed?
Hollow tube formed by invagination of the surface cells (ectoderm) in embryo
What is the function of pharyngeal slits in aquatic and terrestrial species?
Aquatic: slits and puches creater water current between mouth and pharynx for feeding and respiration
Terrestrial: transient embryo structures and slits not opened in pouch wall
Other than vertebrata what are the chordate subphyla? Give examples of each.
Cephalochordata –> lancelets of amphioxus (no differentiated brain, special sense organs, or heart)
Urochordata –> tunicates, Ascidiacea (swimming larvae, rudimentary heart, become stable sea squirts)
What is the flow of blood in lungfishes in air?
How does this change in water?
(Low oxygen blood) –> Right side of heart (sinus venosus, atrium, ventricle, conus arteriosus) –> last aortic arch (closest to heart) –> pulomary artery –> lung –> pulmonary vein –> Left side of heart –> ventral aorta –> aortic arches (no gills) –> dorsal aorta –> tissues
In water:
After right side of heart –> aortic arches with gills –> tissues
*note: most circulation through heart is going to be on right side because deoxygenated; doesn’t go through pulmonary artery or lungs.
