Protochordates and The Origin of Craniates

Question 1

Also known as enterocoelomates because their coelom develops through enterocoely

Answer 1

deuterostomes

Question 2

proposed a taxonomic classification of deuterostomes

Answer 2

Ernst Haeckel (1874)

Question 3

Four extant phyla of deuterostomes

Answer 3

Xenoturbellida
Echinodermata
Hemichordata
Chordata

Question 4

Invertebrate extant phyla of deuterostomes

Answer 4

Xenoturbellida
Echinodermata

Question 5

coelom forms when the mesoderm splits, doe

Answer 5

protostomes

Question 6

the coelom forms when the mesoderm pinches off through the process of enterocoely, merges with coelom

Answer 6

deuterostomes

Question 7

Closest relatives of vertebrates along with the hagfish
Provide clues to the invertebrate origin of animals with backbones

Answer 7

Protochordates

Question 8

Protochordates are composed of subphylums:

Answer 8

Hemichordata
Urochordata
Cephalochordata

Question 9

Phylum
Unique calcium carbonate skeleton
Secondary radial symmetry in adults
Bilateral symmetry in early life stage

Answer 9

Phylum Echinodermata

Question 10

Commonly known as acorn worms
Vermiform bottom dwellers found in shallow mud water
Fragile and can reach up to 5 feet in length
can be in freshwater

Answer 10

Phylum Hemichordata

Question 11

Proposed classification of Hemichordata in 1870 by Gregenbaur

Answer 11

Enteropneusta

Question 12

Proposed classification of Hemichordata in 1874 by Haeckel

Answer 12

Phylum Chordata

Question 13

Proposed classification of Hemichordata in 1884 by Bateson

Answer 13

Subphylum Hemichordata

Question 14

Subphylum Hemichordata example

Answer 14

acorn worm

Question 15

Bateson’s considerations placing Phylum Hemichordata under Phylum Chordata

Answer 15

Collar nerve cord is dorsally located with lumen

Have slits that open to the exterior in lateral walls of the foregut

Have a stomochord, short diverticulum of the foregut

Question 16

findings ultimately showed that it is not homologous to the chordate notochord

short diverticulum of the foregut

Answer 16

stomochord

Question 17

Class

Wormlike acorn worms

Mucus-covered body

Active proboscis collects food in mucous strands

Cilia carry particles to groove at the edge of the collar, then to the mouth

Thrust proboscis into mud and ingest mud to extract the organic matter

Sexes are separate

Fertilization is external

At least one species undergoes asexual reproduction

Answer 17

Class Enteropneusta

Question 18

connects protocoel with a proboscis pore to the outside in Class Enteropneusta

Answer 18

Buccal diverticulum

Question 19

________ of body musculature forces excess water out through the gill slits in Class Enteropneusta

Answer 19

Contraction

Question 20

Roll of gill pores is part of _________ that connects with series of gill slits in sides of pharynx in Class Enteropneusta

Answer 20

branchial system

Question 21

Primarily ciliary-mucus feeders using U-shaped gill slits

Answer 21

Class Enteropneusta

Question 22

Class Enteropneusta has a vessel that expands into a sinus and heart vesicle above the buccal diverticulum

Answer 22

Middorsal vessel

Question 23

Blood enters network of blood sinuses called _______ and then through an extensive system of sinuses to the gut and body wall in Class Enteropneusta

Answer 23

glomeruli

Question 24

in Class Enteropneusta, consists mostly of a

Answer 24

subepithelial plexus

Question 25

in Class Enteropneusta, formed by an invagination of ectoderm (hollow in some species)

Answer 25

Dorsal nerve cord (neurocord)

Question 26

in Class Enteropneusta, a ________ larva develops similar to that of echinoderm larva

Answer 26

ciliated tornaria

Question 27

Basic plan similar to that of Enteropneusta Small animals, usually 1 to 7 mm in length Many individuals may live together in collagenous tubes (zooids are not connected) Ciliated grooves on tentacles and arms collect food Both dioecious and monoecious species Asexual reproduction is by budding

Answer 27

Class Pterobranchia

Question 28

Body divided into three regions in Class Pterobranchia

Answer 28

proboscis, collar and trunk

Question 29

Similarties between hemichordates and echinoderms

Answer 29

Bilaterally symmetrical larvae Similar in certain developmental processes, in muscle proteins, etc. In addition to the dorsal nerve cord, there is another one on the ventral surface, as in invertebrates Deuterostomous development

Question 30

Sequence analysis of the gene encoding the small subunit of rRNA supports a deuterostome clade by which taxa

Answer 30

Echinodermata Hemichordata Chordata

Question 31

should be classified close both to echinoderms and protochordates but in a separate taxon

Answer 31

Hemichordates

Question 32

Marine chordates Notochord is found in the locomotive tail of the free-living larval stage Enclosed in tunics Filter feeders

Answer 32

Subphylum Urochordata

Question 33

Subphylum Urochordata 3 classes

Answer 33

Ascidiacea Larvacea Thaliacea

Question 34

Urochordata class Sea squirts are the best known urochordate Can either be solitary or colonial Larvae are tiny and have a fleeting existence lasting for a few minutes to a few days and do not feed Presence of uninucleated striated muscles

Answer 34

Class Ascidiacea

Question 35

Urochordata class Nervous system consists of dorsal hollow nerve cord, several ganglia and nerves Definitive blood cells and a functional heart does not differentiate until metamorphosis Adhesive papillae attaches the larva to a permanent substrate

Answer 35

Class Ascidiacea

Question 36

used for statoreception in Class Ascidiacea

Answer 36

Otoliths

Question 37

used for photoreception Class Ascidiacea

Answer 37

Ocellus

Question 38

Class Ascidiacea water pathway

Answer 38

Respiratory water  mouth  pharynx  gills  atrium  atriopore

Question 39

Class Notochord is resorbed and becomes source of nutrients during metamorphosis Nervous system location is altered and rearrangement of viscera takes place Water flows through slits into atrial cavity and out through excurrent siphon

Answer 39

Class Ascidiacea

Question 40

Class Called sea squirts because they discharge a jet of water when disturbed

Answer 40

Class Ascidiacea

Question 41

______ becomes the incurrent siphon (anterior) Class Ascidiacea

Answer 41

Larval mouth

Question 42

______ becomes the excurrent siphon (dorsal) Class Ascidiacea

Answer 42

atriopore

Question 43

Class Ascidiacea Water entering the incurrent siphon passes through a ciliated perforated

Answer 43

pharynx with an elaborate basketwork

Question 44

Class Ascidiacea Feeding depends on the formation of a mucous net that is secrete by the ____

Answer 44

endostyle

Question 45

Class Ascidiacea on gill bars of pharynx pull mucus into a sheet Particles trapped in sheet are worked into a rope and carried back to the esophagus and stomach Polyp becomes a filter feeder because of this

Answer 45

Cilia

Question 46

circulatory system of Class Ascidiacea

Answer 46

Heart drives blood first in one direction, then in reverse

Question 47

gland that samples incoming water and may have an endocrine function

Answer 47

Subneural gland

Question 48

with a single ovary and a single testes and fertilization is external in Class Ascidiacea

Answer 48

Hermaphroditic

Question 49

Adult sea squirts retain 2 of 5 chordate features

Answer 49

Pharyngeal slits Endostlye

Question 50

Tadpole larvae have all 5 chordate characteristics

Answer 50

true

Question 51

class Planktons on surface water or deep sea With a long body and a long flat locomotive tail supported by a notochord Retain larval form yet is sexually mature Resemble the larval stages of other urochordates

Answer 51

Class Larvacea

Question 52

class Surrounded by a thick, delicate hollow sphere of mucus interlaced with passages for water entry produced by the larva Phytoplankton and bacteria trapped on a feeding filter inside the sphere are drawn into the branchial basket through pulsating movement

Answer 52

Class Larvacea

Question 53

Class Larvacea When ______become clogged with wastes, they are left behind and a new sphere is built

Answer 53

feeding filter

Question 54

Colony may be linear or it may consists of a floating water-filled sac Incurrent aperture projects into the sea and excurrent aperture empties into the saccular chamber Colonies move with water current Only one order has a free-living larval stage and has a very short-life span

Answer 54

Class Thaliacea

Question 55

class Thaliacea has No notochord to be described

Answer 55

true

Question 56

the correct morphological development or evolution

Answer 56

Pedomorphosis preceding Peramorphosis

Question 57

Any outcome arising from evolutionary changes in developmental rates (see heterochrony) that involves the addition of new stages to the end of the ancestral development sequence.

Answer 57

Peramorphosis

Question 58

process of development in which an organism retains juvenile characteristics into adulthood,

Answer 58

Pedomorphosis

Question 59

Generally called amphioxus (sharp at both ends) or lancelet (little spear) Marine forms in sandy beaches Filter feeders by burrowing in the sand, making a U-turn and having the oral hood protruded Hollow nerve cord lies above the notochord Pairs of spinal nerve roots emerge at each trunk segment Anterior nerve cord is not enlarged, yet is homologous to vertebrate brain Sexes are separate Gametes are set free in the atrium and pass out through atriopore Fertilization is external Larvae soon hatch and gradually assume the shape of adults

Answer 59

Subphylum Cephalochordata

Question 60

Subphylum Cephalochordata Genera:

Answer 60

Branchiostoma and Asymmetron

Question 61

has the five distinctive characteristics of chordates in simple form

Answer 61

Amphioxus

Question 62

in Amphioxus, Water enters the mouth directly driven by cilia in the _______

Answer 62

buccal cavity and pharynx

Question 63

in Amphioxus, Water passes through pharyngeal slits where food is trapped in mucus secreted by the

Answer 63

endostyle

Question 64

in Amphioxus, Food is moved through gut via cilia concentrated in areas called the

Answer 64

ileocolic ring

Question 65

in Amphioxus, Food particles separated from mucus are passed into _______ where they are phagocytized

Answer 65

in Amphioxus,

Question 66

in Amphioxus, Filtered water leaves body by an

Answer 66

atriopore

Question 67

Closed circulatory system is complex but lacks a heart in Amphioxus

Answer 67

true

Question 68

how does blood flow in amphioxus

Answer 68

Blood is pumped by peristaltic contractions in ventral aorta, passes upward through branchial arteries in pharyngeal bars to paired dorsal aortas Blood moves by microcirculation through tissues and returns to ventral aorta

Question 69

Blood lacks ________ and mainly transports nutrients in amphioxus

Answer 69

erythrocytes and hemoglobin

Question 70

Sense organs are simple, including an unpaired _______ that functions as a photoreceptor in amphioxus

Answer 70

ocellus

Question 71

Subphylum Cephalochordata is a diverticulum resembling the vertebrate pancreas in secreting digestive enzyme

Answer 71

Cecum

Question 72

Subphylum possesses features that suggest the vertebrate plan Trunk muscles resemble vertebrate patterns Posses basic circulatory plan of vertebrates

Answer 72

Cephalochordata

Question 73

Differences of Cephalochordata From Vertebrates

Answer 73

Almost no cephalization and no paired sense organs No vertebral column Has pharyngeal slits in large numbers Brain lacks major craniate subdivisions Segmented musculature extends to the anterior tip of the head One-layered external integument No muscular heart Coelom is found in adult forms only

Question 74

Similarities of Cephalochordata From Vertebrates

Answer 74

Big five Segmented or metameric musculature Two layered skin Blood flow direction in arterial and venous channels Homologous homeobox gene clusters

Question 75

have been found in very old rocks, indeed, predating the origin of the vertebrates

Answer 75

Fossil cephalochordates

Question 76

earliest known cephalochordate found in South China (Early Cambrian)

Answer 76

Yunnanozoon

Question 77

cephalochordate fossil found in BC, Canada (Middle Cambrian)

Answer 77

Pikaia

Question 78

eel-like; earliest known chordata fossil somewhat similar to Pikaia

Answer 78

Cathaymyrus

Question 79

A Vertebrate Larva

Answer 79

Ammocoete Larva

Question 80

Shows evidence that vertebrates share a common ancestor with protochordates Notochord that commence from the midbrain and continues to the end of the body (no vertebral column)

Answer 80

Ammocoete Larva

Question 81

Dorsal hollow nerve cord develops as of the amphioxus but with a tripartite brain Seven pair of gill slits open to the exterior for respiration Skin is multilayered Body wall musculature provides locomotion Filter feeders

Answer 81

Ammocoete Larva

Question 82

Hypobranchial groove in ammocoetes sink and becomes the

Answer 82

subpharyngeal gland

Question 83

Ammocoetes and amphioxus difference in diverticulums

Answer 83

Ammocoetes have a solid liver diverticulum which the amphioxus has a saccular diverticulum at the same location but are not analogous

Question 84

Food particles are trapped in mucus produced by the ________which is homologous to the hypobranchial groove of amphioxus

Answer 84

endostyle

Question 85

Larva that has a: Circulatory system with heart (sinus venosus, atrium and ventricle) and RBC Sense organs are present such as otic vesicles (precursor of membranous labyrinth but not for hearing), olfactory sac (chemoreception associated with feeding) and pineal and parapineal organs (act as photoreceptors) Paired lateral eyes eventually form but are rudimentary

Answer 85

Ammocoete Larva

Question 86

which collect body fluid for processing and excretion in Ammocoete Larva

Answer 86

funnel-like nephrostomes

Question 87

in Ammocoete Larva, Fluids are expressed into the coelom via

Answer 87

glomeruli

Question 88

in ammocotes, _increase in number as larvae elongates and lead to ducts which empties to the exterior near the anus

Answer 88

Tubules

Question 89

Gonad is paired early in larval life and becomes unpaired later in ammocoetes

Answer 89

true

Question 90

Bottom-dwelling organisms from the Late Cambrian Sucked up organic material from the sediment like vacuum cleaners Most ancient agnathan or jawless fish Extinct by the Devonian because they could not compete with other jawed fishes

Answer 90

Ostracoderms

Question 91

Cartilaginous internal skeleton Dorsoventrally flattened Cartilaginous internal skeleton Dorsoventrally flattened Dorsal eyes Armored head

Answer 91

Ostracoderms