CH 34- WS 6 vertebrates

Why are amphibians found in damp or aqueous habitats?

1. rely on moist skin for gas exchange 2. eggs must be laid in moist environments to not dehydrate (they lack a shell)

Suppose the lancelets lacked a gene found in tunicates and vertebrates. Would this imply that the chordates' most recent common ancestor also lacked this gene?

No. The gene could have been lost in the lancelet lineage, yet retained in other chordates.

Do all amphibians have an aquatic and terrestrial life stage?

no!

Why are humans and other tetrapods considered "bony fish?" (what characteristic do they all share?) What is the scientific name for "bony fish"?

bone with muscle pelvic and pectoral fins of lobe- finned fish evolved into limbs and feet osteichthyans (fish)

Describe the function of the 4 chordate characters of an adult in clade cephalochordata.

cephalochordata: lancelets 1. notochord: contraction of muscles, supports movement 2. dorsal, hollow nerve cords: nervous system 3. post anal tail: burrows into sand 4. pharyngeal slits/ clefts: gas exchange, food filter

Describe a unique trait about the clade Myxini.

(Hagfish) Were thought to be invertebrates, but were found to have a rudimentary vertebrae of cartilage.

Name the three vertebrate egg fertilization types, and what species they describe.

(birds) oviparous: lay eggs that hatch outside of the mother's body ovoviviparous: retain fertilized egg in the oviduct Nourishment comes from egg yolk. Born after hatching in the uterus. (humans) viviparous: young develop within the uterus. Nourishment prior to birth from mother's blood

What are the three ways a viviparous embryo gets its nutrients?

-through a yolk sac placenta -absorbing nutritious fluid produced by uterus -eating other eggs

How do the four chordate characteristics develop in humans?

1. Notochord: reduced, forms gelatinous disks in between vertebrae. 2. Dorsal, Hollow nerve cord: becomes central nervous system (spinal cord, brain) 3. Post anal tail: reduced in empryonic development 4. pharyngeal slits/ clefts: arches develop into inner ear, jaw

List the four derived characters unique to chordatas and their functions

1. notochord: skeletal support through length of Chordate 2. dorsal, hollow nerve cord: develops central nervous system (spinal cord, brain) 3. post anal tail: extends posterior to anus, contain skeletal elements, helps propel aquatic species. 4. Pharyngeal slits/clefts: slits that open to the pharynx, used for gas exchange

How could you morphologically distinguish between clades Actinopterygii, Actinistia, and Dipnoi?

Actinopterygii: - ray- finned, bony rays support fin Dipnoi: - lobe finned, have lungs and surface to breathe air, freshwater Actinistia: - lobe finned, marine water, 3- lobed caudal fin (tail)

Describe the frog's life cycle.

Larval stage: tadpole -aquatic -herbivore -gills -tail -lateral line system develop through metamorphosis adult stage: frog -legs -lungs -external eardrums -digestive system (adapted for carnivorous diet) -tail, gills, lateral line system resorbed lay eggs in water

What are lobe- finned fish called? name three subclasses of them. What is a distinguishing feature?

Sarcoptergyii -actinistia (coelacanths) -Dipnoi (lungfishes) -tetrapods rod-shaped bones surrounded by a thick layer of muscle in pectoral, pelvic fins

What derived characters do sharks and tuna share? What distinguishes tuna from sharks?

Share: Both are gnathostomes, have jaws, four clusters of hox genes, enlarged forebrains, and lateral line systems. Tuna: bony skeleton, operculum, swim bladder, flexible rays to support fins. Shark: cartilage skeleton, spiral valve

Scientists think amphibian populations may provide an early warning system of environmental problems. What features of amphibians might make them particularly sensitive to environmental problems?

Since many amphibians have a dual life cycle, they are exposed to a wide range of environmental problems (air/water pollution, degredation of habitats). Also have permeable skin that provide little protection from external conditions, and eggs do not have protective shell.

How do Chondrichthyes float?

Their livers hold oil for bouyancy

How do Chondrichthyes hear?

They do not have eardrums, but their entire body transmits sound to hearing organs in inner ear

What are the adaptations birds have for flight?

Weight-saving mods: -lack urinary bladder -only one ovary -small gonads -toothless Wings: -large pectoral muscle ankled to keel on breastbone Feathers: -made of beta-keratin -arrangement into airfoils

In several different animal lineages, organisms with a head first appeared around 530 million years ago. Does this finding constitute proof that having a head is favored by natural selection?

Yes, the finding can be evidence that having a head is favored by natural selection, since it first appeared and never disappeared.

Is it possible that a group of vertebrates that colonized land could have arisen from aquatic gnathostomes other than the lobe- fins?

Yes. the paired appendages of any gnathostomes could have been a strating point for limb evolution. colonization of land could have came from evolving into terrestrial organisms through lineages with lungs

What are ray- finned fish called? Name representative examples. What is a distinguishing feature?

actinopterygii seahorse, eel, tuna, lionfish bones support fins

How do amniotic eggs differ from amphibian eggs? What environment is each egg adapted to?

amniotic: terrestrial environments -shell/ outer barrier to enclose fluid inside egg (amnion) -4 layers -gas exchange, nutrients, waste storage amphibian: aquatic environments -no shell -born outside of parent

What happens to the pharyngeal clefts during embryonic development?

cleft develops into inner ear/glands/jaw

How was the feeding mechanism of a conodont different than that of a lamprey?

conodonts had a jaw with dental elements, and lampreys have a round mouth (cyclostome) that attaches to fish.

How do fish breathe?

draw water through their gills operculum covers gills and filters the water

develop a hypothesis to explain why the diversity of mammals increased in the cenzoic.

endothermic allows them to live in a wide variety of habitats. milk provides a balanced set of nutrients hair/ fat layers help mammals retain heat differentiated teeth large brains absence of large dinosaurs allowed mammals to fill ecological niches, promoting adaptive radiation. continental drift also isolated groups of mommals to promote further variation and evolution of new species.

Name representative examples (extinct/ extant) of Clade Reptilia.

extant: -lizards -snakes -turtles -crocodillians -birds extinct: -plesiosaurs -ichthyosaurs

describe the origin of tetrapods and identify some of their key derived traits.

fins of lobe- finned gnathostomes evolved into limbs of tetrapods. Key derived traits: -four limbs with digits -neck (vertebrae separating head from body) -pelvic girdle (fused to backbone)

What derived character do all tetrapods share?

four limbs with digits

What species are in the superclade gnathostome?

gnathostome= vertebrates with jaws Chondrichthyes (cartilage fish) Actinopterygii (ray- finned fish) Diploid/ Actinistia (lobe- finned fish) Amphibia Reptilia Mammalia

What are the two characters unique to Clade Mammalia?

hair/fur mammary glands (breast milk)

What are two derived characters of gnathostomes?

jaws lateral line systems (organs formed in a row along each side of the body) enlarged forebrain (enhanced vision, smell)

Describe the key adaptations of aquatic gnathostomes.

jaws (feeding) paired fins and tail (swimming) streamlined body (efficient swimming) swim bladders/ other mechanics (bouyancy)

Marsupials -representative -unique traits

kangaroo higher metabolic rates born early, completes embryonic development while nursing (oviviparous) embryonic development in pouch of mom

Decribe the life cycle of a Petromyzontida, including how they feed.

larvae live in freshwater adults migrate to seas most are ectoparasitic: feed by clamping a round mouth (cyclostome) onto a live host. The mouth penetrates the skin and ingests blood/ tissue.

why are humans a part of the lobe- fin clade?

lobe- fins (pectoral and pelvic) evolved gradually into limbs, and gave rise to tetrapods

what is the function of a placenta?

nutrients diffuse from mother's blood to embryo

What are the derived characters of primates?

opposable thumbs forward facing eyes well developed cerebral cortex flat nails parental care

Monotremes -representative -unique traits

platypus lay eggs (oviparous) lack nipples (mammary glands on belly) -young suck milk from fur of mom

Eutharians -representative -unique traits

primates complex placenta develop in uterus (viviparous) longer embryotic stage give birth to developed live young

Suggest key roles that mineralized bone might have played in early vertebrates.

protection from predators. Mineralized mouthparts could also be used for predation/ scavenging

what is the operculum? What does it do?

protective bony flap covering gills helps water filtration out of gills by moving

Describe the key amniote adaptations for life on land.

provides protection for egg supplies fluid

How do reptiles and amphibians morphologically differ?

reptiles have scales

What are the two extant groups of amniotes?

reptiles, mammals

Name some representatives of Clade Amphibia.

salamanders (tails) Frogs (tail-less) Caecilians (legless)

Describe the lancelet's brain, and state it's significance from an evolutionary standpoint.

slightly swollen tip of anterior end of dorsal nerve cord. Hox genes that organize major regions of the brain of vertebrates are expressed in a corresponding pattern of the lancelet nerve cord.

some amphibians never leave water, some survive in relatively dry terrestrial environment. Contrast the adaptations that facilitate these two lifestyles.

some fully aquatic species are paedomorphic (retain larval features for life) terrestrial species in dry environments burrow of live under moist leaves, protect eggs with foam nests or viviparity

Between lungs and swim bladders of ostiechthyans, which is the derived character?

swim bladder derived from lungs

How does the bouyancy control of aquatic osteichthyans differ from chondrichthyans?

swim bladders in osteichthyans (air sacs) oil filled liver in chondrichthyans

What is an amniote? What are the membranes and functions of the amniote?

tetrapod embryo that is in an egg adapted to terrestrial life with four specialized membranes: -amnion (protects the embryo, fluid filled cavity, cushions) -chorion (gas exchange) -yolk sac (contains nutrients) -allantois (disposal sac for metabolic waste)

How do aquatic ostiechthyans breathe?

they draw water through their pharyngeal slits

What is the ancestrial species that evolved into tetrapods?

tiktaalik (fishapod)

Describe the function of the 4 chordate characters of an adult in clade urochordata.

urochordates: tunicates/ sea squirts 1. notochord: resorbed 2. dorsal, hollow nerve cords: degenerates 3. post anal tail: resorbed 4. pharyngeal slits/ clefts: suspension feeding

What structure has taken over the functional role of the notochord in most vertebrates?

vertebrae (enclose the spinal cord)

Are snakes tetrapods?

yes. They have leg bones that are vestigal structures.