zoo exam 5

Why is Tiktaalik considered the ancestor of terrestrial animals?

Provides example of how descendants of lobe finned fish evolved to move on land.. It could not walk far on land but could breath air and prop itself up out of water and walk in water and short distances on land

What are the fish-like structures in Tiktaalik?

Lobed fins, gills, and scales

What are the terrestrial-like structures in Tiktaalik?

• Ribs provide bodily support and air breathing

• Neck allows movement of head

• Front limbs had humerus, then radius and ulna, then small wrist bones

• Pelvic structure for bodily support

how many limbs do amphibians have? how many digits are on these limbs?

4 complex limbs for movement on land, front limbs have 4 digits and hindlimbs have 5

Respiratory systems in amphibians

• Urodela (salamanders, axolotls, newts)

  • Due to varied life stages may have gills, lungs, both or neither

    • Salamanders have aquatic larvae that have gills 

    • if undergo metamorphosis to terrestrial adults lose these gills and have lungs and cutaneous breathing (gas exchange through skin)

    • If larvae remain aquatic they retain gills and cutaneous breathing

• Anura (frogs, toads)

  • lungs primarily, but also cutaneous respiration, CO2 mostly released through skin

  • Positive pressure breathers (breathing forces air into lungs), while humans are negative (breathing pull air into lungs by expanding chest cavity)

• Apoda (caecilians)

  • Cutaneous respiration and lung breathing (2 lungs but one is greatly reduced)

circulatory system of amphibians

• 3 chambered heart

  • 2 atria and 1 ventricle

  • Deoxygenated blood enters right atrium, oxygenated blood from gills/skin/lungs enters left atrium, both atria empty into single ventricle, ventricle pushes deoxygenated blood to gills/skin/lungs and oxygenated blood out to body, there is some mixing of deoxygenated and oxygenated blood in ventricle, but partial septum helps to prevent complete mixing of blood

• Double circuit: blood flows from heart to lungs/skin, back to heart, then out to body

• Urodela

  • Almost all employ cutaneous breathing, skin has extensive vascularization that allows for diffusion of oxygen into blood and CO2 out of blood

sensory system in amphibians

• Eyes see color 

• Well developed hearing (evolutionary novel trait) in some (frogs, toads) but not salamanders

• Internal nostrils w nasal cavity

• urodela (salamanders, axolotls, newts)

  • No external but have internal ear, hearing through bone conduction

• anura (frogs, toads)

  • Have exceptional hearing due to complex external ears w extra bone, auricular operculum, internally

  • Sight is primary sense, have eyelids to keep eyes moist and clean, retina has both cones and rods (cones allow for color vision)

• apoda (caecilians)

  • Mostly blind, limited sight

  • No external ear, very simple ear, hearing limited to bone conduction

novel amphibian vertebrate trait

• 4 complex limbs to move freely on land

• Front limbs have 4 digits while hindlimbs have 5 (hindlimbs reduced or absent in some orders)

how do amphibians maintain body temp?

• Ectotherms (homeothermic)

  • Body temp maintained environmentally not from metabolic activity

how do amphibians reproduce?

• Most have water dependent reproduction and water dependent embryo development

• Cool, wet habitat needed for reproduction

• Urodela

  • Reproduction is internal fertilization, oviparous

  • Male gives female spermatophore which she inserts into cloaca

  • Eggs fertilized internally then female lays eggs in or near water

• Anura

  • Reproduction is external fertilization

  • Mating takes place in water, male grasps female around middle (amplexus), female secretes gelatinous mass and lays eggs in mass, then male releases sperm over eggs which often attach to vegetation in water

  • Eggs develop in water

  • Few exceptions to typical anuran reproduction

    • Male poison dart frog

    • Female marsupial frog

    • Female surinam frog

• Apoda

  • Reproduction is internal fertilization

  • Males have copulatory structure similar to male shark claspers, deposit sperm insides female body

  • Primitive caecilians are oviparous, lay eggs in/near water

  • Advanced caecilians are viviparous bear live young

what is the complete metamorphosis of larval amphibians?

• Eggs must be protected from desiccation, typically laid in water or on moist surfaces

• Aquatic larval offspring hatches from egg

• Larvae undergo metamorphosis to shift from aquatic form to adult terrestrial form

• Urodela 

  • Most exhibit complete metamorphosis:

  • Larvae have gill buds, no limbs > developing gills and limbs > fully developed gills and limbs > adult w fully functional lateral limbs, no gills

  • Axolotls retain larval stage

• Anura

  • Tadpole larvae hatch in water and has many fish like characteristics

    • Herbivorous, gill buds develop into gills, lateral line, long finned tail

  • Tadpole undergoes complete metamorphosis into adult frog

    • Develops lungs, leg buds, external ear drum, develops carnivorous digestive system

    • Gills and lateral line disappear at same time

    • Hind legs develop before front legs

    • Tail slowly reabsorbed

• Apoda

  • Larvae hatch from eggs, in some species larvae fully developed when hatched, other species larvae undergo metamorphosis

  • Live youngs hatch fully developed w exception of gills they lose almost immediately

what are the differences between the 3 orders or amphibians?

• Urodela “tail evident”, salamanders, axolotls, newts etc.

  • ~775 species

  • Most ancestral of all amphibians

  • Legs are same size and shape and located laterally on body, walk by bending body 

  • Mouth: pedicellate teeth present in top and bottom jaw

    • Larvae and adults carnivorous

  • Most considered paedomorphic, retain larval characteristics into adulthood (mudpuppies, axolotls)

  • Due to varied life stages may have gills, lungs, both or neither

    • Salamanders have aquatic larvae that have gills 

    • if undergo metamorphosis to terrestrial adults lose these gills and have lungs and cutaneous breathing

    • If larvae remain aquatic they retain gills and cutaneous breathing

  • Red spotted newt, Notophthalmus viridescens, has aquatic larvae, terrestrial sub adult, aquatic adult

• Anura “without tail”, frogs and toads

  • ~7500 species

    • Ranidae: most commonly known frogs in N America, smooth wet skin, long hind limbs, slim body

    • Hylidae: tree frogs, smooth dry skin, very long hind limbs, slim body

    • Bufonidae: toads, bumpy dry skin, shorter hind limbs, chunky body

  • Relatively strong hindlimbs and arrow shaped skeleton, hind limbs exstensor thrusts allow them to jump

  • Skull attached to back vertebrae (no real neck), 9 vertebrae w elongated urostyle (fused coccyx)

  • Skin is permeable

  • Skin secretes mucus containing toxins

  • Vocal cords and larynx, developed in males more than females

  • Most have maxillary and vomerine teeth only in upper jaw, grab prey w sticky tongue and pull prey into mouth, crush w teeth then pushy prey down throat by sinking their eyeballs into their skull

• Apoda “no legs”, caecilians

  • ~250 species

  • Slender elongated body, can have several hundred vertebrae

  • Derived trait of no limbs

  • Have teeth in upper and lower jaw, they are predators

what are the 3 types of skulls present in amniotes?

• Anapsid (no temporal hole)

• Diapsid (2 temporal holes)

• Synapsid (1 temporal holes)

Which groups have which type of skull?

• Anapsid

  • Early amniote groups that are now extinct (Parareptiles)

  • Present in turtles but evolutionarily they are diapsids

• Diapsids

  • Present in birds and reptiles, such as crocodilians, dinosaurs, tuataras, squamates

• Synapsid

  • Present in mammals and extinct therapsids

What is the dilemma with testudines skulls?

• Turtles are anapsid (no temporal hole), but due to secondary loss of temporal holes

• Evolutionarily they are diapsids (2 temporal holes)

what types of organs/systems are found in reptiles?

• Respiration occurs in lungs only

  • Lungs larger with more surface area than in amphibians, due to greater metabolic demands

  • Costal breathing (pulling air into lungs by expanding ribs/lungs), type of negative pressure breathing 

• Brain has larger cerebrum and cerebellum compared to amphibians 

  • Larger cerebellum associated with increased sensory systems and better control of muscles associated with movement

  • Most reptiles have excellent full color vision

• Crocodilia

  • Sensory system: well developed sight and hearing

    • Vocalize during mating ssn

    • Can see in color underwater and at night

    • Transparent lens to protect eyes underwater limits sight

    • Have nearly 180 vision allows for tracking prey

    • Thick eyelids to protect eyes can pull eyes into skull

  • Primitive 4 chambered heart

• Squamata: 

  • Lizards sensory system: have movable eyelids, external ears, Jacobson’s organ

    • Can focus eyes by changing shape of lens

    • Have color vision

    • Have external ear but hearing not important for most

    • Use tongue to bring enviro chemicals to Jacobson’s organ on roof of mouth

  • Snakes sensory system: do not have moveable eyelids or external ears, do have Jacobson’s organ

    • Focus by moving lens backwards and forwards and moving its head 

    • Most have poor vision, other sense more important

      • However, arboreal snakes have excellent vision

    • Internal ear only, hearing is mostly vibrations

    • Use tongue to bring environmental chemicals to Jacobson’s organ on roof of mouth

    • Boids and pit vipers have heat sensing pits along jawline to sense infrared heat

how does blood flow through reptile circulatory system?

• 3 chambered heart (2 atria and 1 ventricle)

  • Exception: alligators and crocs have primitive 4 chamber heart

• Double circuit: blood flows from heart to lungs back to heart, then out to body

• Deoxygenated blood from body enters right atrium and goes to ventricle >  pumps blood into lungs and is re oxygenated > oxygenated blood flows from lungs to left atrium and back into ventricle > ventricle contains oxygenated and deoxygenated blood with little mixing due to partial septum and diff in pressure in atria compared to ventricle (this attributes to higher blood pressure in reptiles than amphibians)  > mostly oxygenated blood then pushed to aorta and out to body

defining chracteristics of reptiles?

• Novel adaptation of amniotic egg and thick, scaly, waxy skin with scales (containing keratin and waxy lipids)

• Defining characteristic of  keratinized epidermal structures (scales, claws, horns, feathers)

• Stronger jaws, larger teeth than amphibians

• Shed their skin periodically to grow and remove ectoparasites

  • Snakes shed at once, while other reptiles shed in patches

• Ectotherms (homeothermic)

  • Body heat from enviro, bask in sun for warmth and seek shade to cool

  • Metabolic activity not required to maintain body temp

  • Reptiles can live on 10% calories required by similar size endotherm and eat sporadically

• Sphenodontia: Tautaras

  • upper jaw has 2 rows of teeth, lower jaw has 1 row that sit between upper rows when mouth is closed

• Squamata: snakes

  • Secondarily legless, boidae (boas) and pythonidae (pythons) have vestigial rear “limbs”

  • Flexible skull with 8 joints, lower jaw has no bony or ligamentous attachment to upper jaw and 2 halves of lower jaw joined by muscle only 

  • Teeth curved backwards allowing snakes to swallow large prey

  • More vertebrae which are shorter and wider than most tetrapods allowing fast, undulated

• Testudines: turtles

  • all species have bony shells that are part of their skeleton

    • Shell overlaid w large scales

    • Dorsal shell called carapace, and includes backbone and ribs, broadening of ribs was first evolutionary step towards shell

    • Ventral shell called plastron

    • Carapace and plastron are connected to eachother by bridge, bones between front and back legs

    • Some can draw head and legs up into carapace

how do reptiles reproduce?

• Crocodilia

  • Sexual reproduction w internal fertilization

• Sphenodontia

  • Sexual reproduction via internal fertilization

    • Slow to sexually mature ~25 years

    • Males don’t have penis, sperm transferred by rubbing cloacas

    • Females can store sperm up to a year

    • Females oviparous, eggs incubate 7-12 months

    • No parental care

• Squamata 

  • Lizards

    • sexual w internal fertilization

      • Males have 1-2 penises, transfer sperm internally

      • In most females oviparous

        • Lay eggs, no parental care

        • Eggs are leathery soft

        • Sex determined by sex chromosomes

      • Few species ovoviviparous

        • Female gives birth to fully developed young w young obtaining nourishment from egg yolk

      • Parthenogenesis observed in a number of species

        • Females reproduce asexually by combining a polar body w egg

  • Snakes

    • sexual w internal fertilization

      • Males have 1-2 penises, transfer sperm internally

      • In most species females are oviparous

        • Lay eggs, no parental care (however female pythons do guard their eggs)

        • Eggs are leathery soft, sex determined by sex chromosomes

        • Few species are ovoviviparous

          • Eggs hatch in mothers body, little to no parental care after birth

        • Parthenogenesis observed in number of species

          • Females reproduce asexually by combining polar body w egg

• Testudines

  • Sexual reproduction via internal fertilization

    • Males have penis

    • Females oviparous

    • Lay eggs on land

    • No parental care

    • Young turtles hatch fully formed

temp dependent reproduction in reptiles

• Crocodilia

  • <86 (cooler temps): females

  • >91 (warmer temps): males

• Sphenodontia

  • Very narrow temp dependent sex determination

    • 68 degrees or lower: female

    • 72 degrees or higher: male

    • 70 degrees: equal chance of male/female

• Squamata

  • NO temp dependent reproduction, sex determined by # of chromosomes

• Testudines 

  • Below 82 degrees (cooler temp): male

  • Above 89 degrees (warmer temp): female

respiratory system in birds

• 9 air sacs connected to lungs, inspired air skips lungs and instead goes to posterior air sacs which serve as reservoir for air

• Birds must complete 2 inhalation/exhalation cycles for single breath of air to pass through

  • 1st inhalation: air bypasses lungs and goes to posterior air sacs

  • 1st exhalation: air from 1st inhalation moves into lungs

  • 2nd inhalation: air moves from lungs to anterior air sacs at same time as new air moves to posterior sacs

  • 2nd exhalation: air in anterior sacs leaves body, air in posterior sacs move into lungs 

• This complex system means there is always fresh, oxygenated air within the respiratory system

Excretory and Reproductive system in birds

• No urinary bladder

  • Have cloaca connected to digestive, urinary, and reproductive

  • Allows water to be absorbed from waste, no liquid waste, urate salts expelled w feces

• Females only have one ovary

• In both sexes, gonads change size throughout year

  • Shrink significantly during non breeding season

  • Grow considerably during breeding season

sensory system in birds

• Nervous and sensory systems must meet demands of complex flight

  • Cerebrum enlarged to control social behavior, flying, complex problem solving, muscle movement, equilibrium, balance

  • Intelligent birds have larger cerebrum than less intelligent birds

  • Very large optic lobe to process visual information associated with flight, finding food, reproductive behavior, etc

• Acute, color vision

• Complex vocalization/communication

  • Many have elaborate songs used to define territory, attract mates, etc.

blood flow through bird circulatory system

• 4 chambered heart (2 atria, 2 ventricles)

• Oxygenated and deoxygenated blood kept completely separately

• Deoxygenated blood from body enters right atrium then goes to right ventricle > blood then sent to lungs where oxygenates (pulmonary circulation) > then returns back to heart, entering left atrium and then left ventricle > from left ventricle it enters aorta and goes out to body (systemic circulation)

• Deoxygenated blood stays on right side of heart, oxygenated blood on left

how do birds reproduce?

• Females only have one ovary

• In both sexes, gonads change size throughout year

  • Shrink significantly during non breeding season

  • Grow considerably during breeding season

• Most species males do not have penis 

• Sperm transferred through “cloacal kiss”

• Female is oviparous

what type of fertilization do birds have?

internal fertilization

What type of egg development do birds have?

oviparous

What are the differences between altricial and precocial chicks?

• Altricial chicks: hatch blind, no/minimal feathers, unable to move around

  • Require extended and significant parental care 

  • Songbirds, woodpeckers, parrot, pelican, baby robins,  etc

• Precocial chicks: hatch w open eyes, feathers, able to move around

  • Able to leave nest, walk/run/swim, and find food within a few days, but parents still provide care until they are able to fly

  • Chicken, water birds such as ducks and geese, rhea

What is the defining characteristic of the double circuit in vertebrate circulatory system?

Blood flows into the heart, then from the heart to the respiratory organs, then back to the heart.

Which of the following are general characteristics of most amphibians?

• water dependent reproduction 

•  complete metamorphosis 

•  three chambered heart

What is the most significant result of the evolution of the amniotic egg?

Tetrapods are no longer tied to the water for reproduction

Which structure of the amniotic egg provides gas exchange for the embryo?

Chorion

The following accurately describes amphibian blood flow:

Oxygen poor blood enters the right atrium and is then pumped into the ventricle. It is then pumped out to the respiratory structures where it is oxygenated. The oxygenated blood returns to the left atrium and is then pumped into the ventricle. A mix of oxygenated and deoxygenated blood is then pumped out to the body.

Which amniotic egg structure is derived from the embryo's midgut?

Yolk sac

Amniotes have all of the following derived traits except ___________

Water dependent reproduction

Which of the following is a defining characteristic of all adult amphibians?

Moist skin maintained by mucus glands

Tiktallik provides an example of how animals transitioned from water to terrestrial life. Tiktallik has some fish-like traits and some terrestrial traits. Which of the following is terrestrial trait?

Ribs for body support and breathing air.

In the amphibian Order _______________, the males give the females a spermatophore filled with sperm. If the female accepts the male, she will insert the spermatophore into her cloaca to fertilize her eggs

Urodela

describe metamorphosis of a tadpole into an adult frog

frogs undergo external fertilization in bodies of water where males place layer of sperm over eggs. after eggs develop, tadpoles hatch and undergo complete metamorphosis. they develop structures like lungs, leg buds, digestive sys, and external ear drum. gills and lateral line then go away and hind and front legs develop. lastly, tail is reabsorbed slowly

what are benefits of the amniotic egg?

provides embryo with internal aquatic enviro therefore tetrapods are no longer reliant on water for reproduction

what are the parts of the amniotic egg and its function?

• amnion: surrounds embryo, protecting it from dehydration and physical damage

• chorion: facilitates gas exchange (oxygen and co2) between embryo and enviro

• allantois: stores nitrogenous waste products and facilitates gas exchange

• yolk sac: provides nutrients to developing embryo

• protective shell: outer layer of amniotic egg, made of calcium carbonate

• albumen: between shell and chorion, helps provide liquid protein and cushioning for embryo

3 characteristic that differentiate lizards and snakes

1. lizards have movable eyelids while snakes lack movable eyelids, they focus on moving the lens back and forth and shifting their heads

2. lizards have external ear and snakes have internal ear and use vibrations to “hear”

3. lizards have 4 limbs while snakes are legless

what are 2 benefits of flight?

allows for escape from predators and allows for access to more food sources

blood flow in amphibians vs reptiles

they both have double circuit , blood flows from heart to skin/lungs, back to heart and then out to body

Describe temp dependent sex determination in Crocodilia, Sphenodontia, and Testudines

Temperature dependent sex determination dictates the temperature which produces a certain sex, male or female, while in the egg. In Crocodilia, cooler temps (<86 degrees) produce females and warmer temps (>91 degrees) males. Sphenodontia have a very narrow range with 68 degrees or lower producing females and 72 degrees or higher producing males. Eggs kept at 70 degrees have an equal chance of being male/female. Testudines is reverse of the previous species; cooler temps (<82 degrees) produces males and warmer temps (>89 degrees) produces females

Describe 3 (only 3) adaptations that allow for flight in birds

3 adaptations that allow for flight in birds are their feather arrangement, which forms wings into airfoils, their light but stable skeleton of pneumatic bones, which drastically reduces weight, and their fused vertebrae (except for cervical) that provides rigid support during flight

All of the following are flight adaptations in birds except?

Internal fertilization

Countercurrent respiration

No urinary bladder

Only one ovary

To which group of chordates does the following circulatory system belong?

Oxygen poor blood enters the right atrium and is then pumped into the right side of the ventricle. It is then pumped out to the respiratory structures where it is oxygenated. The oxygenated blood returns to the left atrium and is then pumped into the left side of the ventricle. It is then pumped out to the body.

reptiles

To which group of chordates does the following circulatory system belong?

Oxygen poor blood enters the right atrium and is then pumped into the right ventricle. It is then pumped out to the respiratory structures where it is oxygenated. The oxygenated blood returns to the left atrium and is then pumped into the left ventricle. It is then pumped out to the body.

birds

Which of the following is not characteristic of all reptiles?

Shed their skin

waxy, scaled skin

Lung respiration

3 chambered heart

Which Reptilian Order has an anapsid skull?

Testudines

In which Reptilian Order do the females provide parental care to their offspring

Crocodilia

Sex is temperature dependent in all Reptilian orders except _________

Squamata

Order Squamata includes snakes and lizards. Although there are many similarities between snakes and lizards which of the following are found in one group but not the other?

Scaly skin

Internal fertilization

Eyelids

Jacobson's organ

Birds are most closely related to _________.

therapod dinos

Which of the following are adaptations for flight in birds?

Pneumatic bones

Wings with feathers

No urinary bladder

Counter current respiration

In birds, typically one male and one female will form what is known as a "mated pair" for a breeding season. Both of them share responsibilities such as building the nest, incubating the eggs, etc. In some species, chicks are bald, blind, and unable to move around when they hatch. Which of the following is true of these checks?

They are probably a species of duck.

They are able to leave the nest within a few days.

They require minimal parental care.

They are altricial chicks.

Why is the amniotic egg a novel adaptation?

• Derived traits associated w amniotic egg

  • Waterproof skin

  • Keratinized structures (nails, claws, horns, etc)

  • Costal respiration, inhalation/exhalation produced by movement of ribs and rib musculature

layers of amniotic egg from outside to inside?

• Outermost layer is water tight, protective shell (in reptiles it’s leathery and in birds shell is hardened made of calcium carbonate)

• Albumen between shell and chorion, provides embryo w water, protein, and cushioning

• Chorion 

  • extraembryonic membrane surrounding embryo, yolk sac, and allantois

  • develops from folds in embryo’s body wall

  • Function is gas exchange between embryo and external enviro

• Amnion 

  • Fluid filled cavity providing embryo w internal aquatic enviro, cushions embryo from shock and provides hydration

  • Develops from fold in embryos body wall

• Yolk sac surrounding yolk is extension of embryo’s midgut, blood vessels in yolk sac transports nutrients to embryo’s circulatory system

Allantois is extension of hindgut, as embryo grows it fuses w chorion to facilitate increased need for gas exchange, stores nitrogenous waste produced by embryo

Key diffs in temporal fenestrae behind each eye (these holes were location of jaw muscle attachment)

• Anapsid (no temporal hole)

  • Present in early amniote groups now extinct

  • Present in turtles due to secondary loss of temporal holes (evolutionarily they are diapsids)

• Diapsid (2 temporal holes)

  • Present in birds and reptiles

• Synapsid (1 temporal hole)

  • Present in mammals and extinct therapsids

Mammals and derived traits

• In mammals egg is replaced by gestational pregnancy, amnion still present as amniotic sac and fluid

• Placenta and umbilical cord derived from yolk sac and allantois, functions in nutrient transport and gas exchange

• Chorion forms most of placenta, mothers uterine lining forms rest of placenta

yolk sac

surrounds yolk

amnion

fluid filled sac surrounding just embryo

chorion

flexible membrane surrounding embryo and all other membranes, facilitates gas exchange

allantois

stores nitrogenous waste, facilitates gas exchange

outer layer (shell)

in reptiles it’s leathery and in birds is hardened made of calcium carbonate