Bilaterians Flashcards

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1
Q

Where did trace fossils first come from?

A

Animals going 3D- mixing sediments- burrowing- swimming- chasing

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2
Q

When did transition from 2D ‘biomat world’ to 3D world occur?

A

Cambrian start

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3
Q

3 clades of bilateria?

A

Lophotrocozoa, Ecdysozoa, Deuterostoma

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4
Q

What phyla included in Deuterostomia?

A

Echonoderms, Hemichordates and Chordates

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5
Q

What do deuterstomia have in common?

A

Deuterostomy and radial cleavage (these arent unique character)

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6
Q

What are the 5 classes of Echinoderms?

A

Asteroids (starfish); ophiuroids (brittle stars); Echinoids (sea urchins); holothurians (sea cucumbers); crinoids (sealilies + feather stars)

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7
Q

What is pentaradial symmetry?

A

5 fold

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8
Q

4 important features of Echinoderms

A

pentaradial symmetry, water vascular system, endoskeleton, marine

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9
Q

What symmetry do starfish and brittlestars have?

A

Bilateral- conserved from bilaterian ancestor?

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10
Q

How do starfish feed?

A

Gut extends down arms. Part of stomach extruded inside out into shell of prey, digestive juices released, can eat!

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11
Q

What is a use of the water-vascular system in Echinoderms?

A

Locomotion

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12
Q

Feature of Ophiuroids (brittle star)?

A

Thinner and bendier = for detritus feeding + NO ANUS

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13
Q

What is between Echinoids ossicle pines (which are covered in living tissue)?

A

Pedicellaria- chop up larvae that land- like little teeth

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14
Q

What do Holothurians (sea cucumber) do when attacked?

A

Eject Cuvierian tubules. If that doesn’t work.. .. then eject intestine!

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15
Q

What are the 2 classes of Hemichordates?

A

Enteropneusts (acorn worms) and Pterobranchs

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16
Q

How do Enteropneusts (acorn worms from Hemichordata) feed?

A

Pharyngeal slits- holes on side of body and cilia to make water current
+ filter feeds

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17
Q

Name 6 features of a generalised chordate

A

Pharyngeal slits; endostyle; dorsal hollow nerve chord; postanal tail; notochord; lateral muscles

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18
Q

Function of Pharyngeal slits in chordates?

A

Feeding and gas exchange

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19
Q

Function of endostyle in chordates?

A

Internal secretory structure of mucus - goes over pharyngeal slits

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20
Q

what germ layer is doral hollow nerve chord derived from in chordates?

A

ectoderm cells

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21
Q

Function of notochord in chordates?

A

Important for locomotion = skeletal structure down center of animal

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22
Q

What are the 3 subphyla of the phylum chordata?

A

Tunicates (urochordates); cephalochordates (amphioxus); vertebrates

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23
Q

What are the 3 groups within Tunicates?

A

Ascidiacaea (sea squirts); Larvacea; Thalacea

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24
Q

What does sessile mean?

A

Immobile

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25
Q

What is name for thick cellulose coat found on Ascidians?

A

Tunic

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26
Q

Where did genes for tunic of Ascidians (sea squirts) come from?

A

Horizontal gene transfer (from bacteria)

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27
Q

What do larvacea look like?

A

Sexually mature tadpoles in jelly houses

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28
Q

What do Thaliacea look like?

A

Sea quirts- but they can SWIM

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29
Q

What are 2 major changes in amphioxus (cephalochordata) body plans?

A

Notochord extends past brain for stiff tip for burrowing.

Pharyngeal slits no longer interact with outside world as water goes in atrial cavity and out atrial pore

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30
Q

What are the 3 clades of bilaterina?

A

Lophotrochozoa, ecysozoa and deutrostomia

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31
Q

What phyla are included in Ecdysozoa?

A

2x wormy; nematodes and nematomorphs

3x leggy; tardigrades onychophora and arthropods

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32
Q

What do ecdysozoa have in common?

A

They moult (ecdysis)

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33
Q

Name 2 characters of nematode worms

A

Stiff (non-stretchy cuticle) and NO segmentation

34
Q

How do nematode worms move?

A

Stiff but bendy cuticle and antagonistic longitudinal muscles = SINOUS BODY WAVES

35
Q

How to nematode worms solve problem of high pressure squeezing out gut contents?

A

Muscles - e.g. triradiate pharynx at mouth

36
Q

How does nematode cuticle have spring effect?

A

Several layers of helical cortical fibres in different directions

37
Q

Give an example of a nematode worm parasite with a 2 host life cycle

A

Onchocerca volvulus= river blindness

- humans and black flies

38
Q

How do we exploit nematode worms?

A

Use as biological control e.g. slug killer

BUT this is introducing invasive species

39
Q

What is the developmental model system nematode worm?

A

C. elegans

40
Q

How are nematomorphs different to nematodes?

A

CRAZY LONG AND REDUCED GUT

41
Q

How do nematopmorph larvae return to water once developing inside adult cricket?

A

MIND CONTROL- makes cricket wander eratically

42
Q

What can tardigrades do when not in water?

A

anyhydrobiosis

43
Q

What is anyhydrobiosis?

A

organism becomes dry and dormant until living conditions are favorable.

44
Q

how were ECDYSOZOA discovered as a clade?

A

DNA sequencing

45
Q

What is a key feature of annelids?

A

Segmentation

46
Q

What clade do lophotrocozoa belong tp?

A

Bilateria

47
Q

What does vermiform mean?

A

Worm-shaped

48
Q

What is a hydrostatic skeleton?

A

big fluid filled spaces (water not very compressible) e.g. in annelids

49
Q

Why are annelids always aquatic?

A

Have water permeable skin

50
Q

What are the 3 classes of annelida?

A

polychaeta, oligochaeta and hurudinea

51
Q

What are the 2 main types of polychaetes?

A

Errant (mobile) and sedentary

52
Q

What are parapodia in polychaetes?

A

Triangles on sides, like oars for extra power

53
Q

How do polychaetes reproduce?

A

dioecious- external fertilisation and larval stage

54
Q

Differences between polychaetes?

A

1- freshwater
2- no parapodia
3- no eyes/ tentacles on head
40- hermaphrodite

55
Q

What does the clitellum do in oligochaetes?

A

secretes mucus coccon to pick up eggs and sperm - then leaves all behind

56
Q

How were leeches used in microsurgery?

A

used for anticoagulants and to remove blood

57
Q

what 3 features of flat worms tell you they’re bilateria?

A

1- three germ layer
2- bilateral symmetry
3- centralised nervous system

58
Q

What feature do flatworms lack that are seen in other bilateria?

A

no body cavity, no gills, no blood system, no anus

59
Q

What is an eversible pharynx?

A

can go inside out e.g. flatworms

60
Q

Where do polyclads exist?

A

MARINE

61
Q

What is a neoblast?

A

adult stem cell

62
Q

what is amazing about triclad (planarian) regeneration?

A

cut any part and whole body will regenerate

63
Q

How do cestodes (parastic flatworms) grow?

A

from middle- pushing segments out

64
Q

what is the second biggest phylum after arthropods?

A

mollusca

65
Q

Name 2 major body plan features of molluscs?

A

trough-gut and not-segmented

66
Q

What are molluscs shells made of?

A

Mantle = extracellular caco3 + proteins

67
Q

why do mollusc shells coil?

A

to increase volume as can only grow at edges

68
Q

What are the 3 main classes of mollusca?

A

gastropoda, bivalvia, cephalopoda

69
Q

What are 3 characteristic traits of gastropoda?

A

1- 1 shell
2- use radula
3- slow moving grazer

70
Q

What is torsion in gastropods?

A

body twists 190 degrees anticlockwise during development

71
Q

What is an interesting defence mechanism in nudibranchs?

A

Eat immature nematocysts from prey- out at tips of cerata and use to sting

72
Q

What are 3 main characteristic traits of Bivalvia (mollusca)?

A

2 shells, foot in between, no radula

73
Q

What is an example of a developed ccephalopod?

A

octopus, squid, cuttlefish

74
Q

how do cephalopoda move?

A

gas in shell for up and down and water expulsion fro propulsion

75
Q

do bivalvia have eyes?

A

not generally but some evolved constructive interference e.g. scallops

76
Q

What are the 3 subphyla of chordates?

A

Urochordates, cephalochordates, vertebrates

77
Q

What are the 2 main components of bone?

A

collagen fibres and calium PHOSPHATE crystals

78
Q

What do osteoblasts do?

A

make bone

79
Q

What do osteoclasts do?

A

break down bone

80
Q

What do osteocytes do?

A

detect strain and cracks

81
Q

What part of body plan, in somite, forms bone?

A

Sclerotome

82
Q

What do neural crest cells form?

A

sensory nerves, pigment cells, nerves in gut and autonomic nervous system + in head forms more skeleton