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Ecology and diversity > Lecture 13 > Flashcards

Lecture 13 Flashcards

1
Q

What evidence is there that deuterostomes all share a common ancestor that is different to protostomes?

A

Early developmental patterns and phylogenetic analysis of gene sequences

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2
Q

What three early developmental patterns characterize deuterostomes?

A
  • Radial cleavage (ancestral)
  • Formation of mouth at opposite end of the embryo from the blastopore (ancestral)
  • Development of a coelom
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3
Q

How is deuterostome coelom development different to that of protostomes?

A

Coelom develops from mesodermal pockets that bud off from the cavity of the gastrula rather than by splitting of the mesoderm

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4
Q

What are the three major clades of deuterostomes?

A

Echinoderms
Hemichordates
Chordates

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5
Q

What are all deuterostomes?

A

Troploblastic, coelomate with internal skeletons

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6
Q

How are segmented body plans of deuterostomes different to those of annelids and arthropods?

A

Segments are less obvious

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7
Q

What fossil has taught scientists about the ancestors of modern deuterostomes?

A

520 million year old fossil beds in china

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8
Q

What ancient fossils had a skeleton similar to modern echinoderm?

A

homalozoans

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9
Q

What ancient fossils had pharyngeal slits?

A

Vetulicosystids

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10
Q

What ancient fossil had a large mouth, six pairs of external gills and a segmented posterior body with light cuticle?

A

Yunnanozoans

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11
Q

What do the ancient deuterostome fossils show?

A

Support phylogenetic analyses of living species showing deuterostomes were bilaterally symmetrical, segmented with pharynx with slits for water flow

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12
Q

What evolved later in some deuterostome evolution?

A

Pentaradial symmetry

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13
Q

How many groups of echinoderms are there?

A

23, 6 remaining

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14
Q

What are hemichordates and echinoderms known as together?

A

ambulacrarians

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15
Q

What are some features of ambulacrarians?

A

Bilateral symmetry

Ciliated larvae

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16
Q

What happens to adult echinoderms?

A

They undergo radical change as they develop into adults to have pentaradial symmetry

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17
Q

What sides do echinoderms have?

A

Oral side (containing mouth) and aboral side (containing anus)

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18
Q

What two unique structural features do echinoderms have?

A

Water vascular systems

Internal skeleton

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19
Q

What does an echinoderm internal skeleton consist of?

A

Calcified internal plates covered by thin layers of skin and sometimes mucus, fused inside body.

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20
Q

What does the water vascular system of echinoderms consist of?

A

A net work of water-filled canals leading to extensions called tube feet.

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21
Q

What is the function of the water vascular system?

A

Gas exchange, locomotion, feeding

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22
Q

How does water enter the water vascular system of echinoderms?

A

A perforated structure called a madreporite

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23
Q

What structure leads from the madreporite and where does it go?

A

Calcified canal lead to another canal that rings the esophagus (ring canal)

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24
Q

What radiates from the ring canal (canal that surrounds the esophagus) in echinoderms?

A

Other canals that extend through the arms connecting with tube feet.

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25
Q

What do echinoderms use tube feet for?

A

Moving and capturing prey

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26
Q

What is a major echinoderm clade that includes sea lilies and feather stars?

A

Crinoids

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27
Q

How do sea lilies attach to a substratum?

A

A flexible stalk consisting of a stack of calcareous discs

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28
Q

Describe the body of a sea lily.

A

Cup shaped consisting of a tubular digestive system, five to several hundred arms (in multiples of 5) extend outwards from the cup.

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29
Q

How are feather stars different from sea lilies?

A

They grasp the substratum with their flexible appendages

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30
Q

What are some other echinoderms, other than crinoids?

A

sea urchins
sea cucumbers
brittle stars
sea stars

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31
Q

Describe the body of a sea urchin.

A

Hemispherical shape, covered with spines attached to underlying skeleton via ball and socket joints.

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32
Q

How are sea cucumbers orientated in an atypical way?

A

Mouth is anterior and anus posterior, rather than oral and aboral

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33
Q

What do sea cucumbers primarily use their tube feet for?

A

Attaching to substratum rather than moving

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34
Q

Where are the gonads and digestive organs located in sea stars?

A

In their arms

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35
Q

What do the tube feet of sea stars function for?

A

Locomotion, gas exchange, attachment

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36
Q

What does each tube foot of a sea star consist of?

A

An internal ampulla connected by a muscular tube to an external suction cup that sticks to the substratum

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37
Q

How are brittle stars different to sea stars?

A

Their flexible arms are composed of jointed hard plates.

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38
Q

Describe sea daisies.

A

Tiny disc shaped body with a ring of marginal spines, two ring canals, no arms.

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39
Q

How do sea lilies feed?

A

By orientating their arms to water currents, food particles stick to tube feet covered in mucus secreting glands, transferred to grooves in arms, ciliary action carries to mouth

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40
Q

How do sea cucumbers catch food?

A

Anterior tube feet modified into feathery sticky tentacles which is periodically withdrawn and wiped in mouth

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41
Q

What do sea stars eat?

A

Polycheates, gastropods, bivalve mollusks, small crustaceans such as crabs and fish

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42
Q

How do sea stars each a bivalve?

A

Sea star pushes its stomach out through its mouth through the space of the shell gap, enzymes digest prey

43
Q

How do sea urchins eat?

A

They scrape algae from rocks using a rasping structure

44
Q

What animals make up hemichordates?

A

Acorn worms and pterobranchs

45
Q

What are the three parts of the hemichordate body plan?

A

Poboscis
Collar
Trunk

46
Q

Where do acorn worms live?

A

Muddy and sandy marine sediments

47
Q

What does the digestive tract of acorn worms consist of?

A

Pharynx

intestine

48
Q

What surrounds the pharyngeal slits of acorn worms?

A

Highly vascularised tissue

49
Q

What are pterobranchs?

A

Sedentary marine animals living in tubes secretes by the proboscis

50
Q

What are the three clades of chordates?

A

Urochordates, cephalochordates, vertebrates

51
Q

What 3 derived structures do all chordates display at some stage during their development?

A
  • Dorsal, hollow nerve cord
  • Tail that extends past anus
  • Dorsal supporting rod called notochord
52
Q

What is the notochord composed of?

A

A core of large cells with turgid fluid filled vacuoles (rigid but flexible)

53
Q

What happens to the notochord in urochordates?

A

It is lost in metamorphosis to adult stage

54
Q

What happens to the notochord in most vertebrates?

A

It is replaced by skeletal structures to provide support

55
Q

What feature is present at some point during the developmental stages of chordates?

A

Pharyngeal slits (not a derived trait)

56
Q

What did the pharynx function as in chordate ancestors/

A

Site of O2 uptake and CO2 removal and water(as in acorn worms)

57
Q

What is the enlarged pharynx in lancelet’s called?

A

The pharyngeal basket

58
Q

What are the three major groups of urochordates?

A

Ascidians
Thaliaceans
Larvaceans
(All marine animals)

59
Q

What are most species of urochordates?

A

Ascidians (sea squirts)

60
Q

What do some ascidians form and how?

A

Colonies

By asexual budding

61
Q

What is the body of an adult ascidian like?

A

Bag like

Enclosed by a tough tunic composed of proteins and polysaccharides secreted by epidermal cells

62
Q

What is the ascidian pharynx enlarged into?

A

The pharyngeal basket- used in filter feeding

63
Q

What do bands of muscle surrounding the notochord of ascidians do?

A

Provide support for body

64
Q

What happens to the larvae of most species of ascidians?

A

They settle on the floor to form sessile adults

65
Q

Where to thaliaceans live? (salps)

A

Singly or in chain like colonies

66
Q

What are larvaceans?

A

Solitary planktonic animals that retain their notochord who snare sinking organic particles in their slimy houses

67
Q

What are lacelets?

A

Small animals who use their notochord for burrowing

68
Q

What do vertebrates have?

A

A jointed, dorsal vertebral column that replaces notochord during early development as their primary supporting structure

69
Q

Where did the lineage that led to vertebrates evolve?

A

In estuarine environment (where freshwater meets salt water)

70
Q

What is believed to be the sister group of vertebrates?

A

hagfishes

71
Q

What does the weak circulatory system of hagfishes consist of?

A

Three small accessory hearts

72
Q

What type of skull do hagfish have?

A

A partial cranium containing no cerebrum or cerebellum (two major brain regions)

73
Q

What else to hagfish lack?

A

No jaw or stomach, vertebrae

74
Q

What type of skeleton do hagfish have?

A

One composed of cartilage

75
Q

What group are hagfish sometimes considered to be?

A

Craniates- if not closely related

Cyclostomes when placed with lampreys

76
Q

What do hagfish eat?

A

Polychaete worms

77
Q

What type of development do hagfish undergo?

A

Direct development

78
Q

Where do lampreys live?

A

Freshwater or coastal salt water (breed in freshwater)

79
Q

What do lampreys have?

A

Complete braincase,
Cartilaginous skeletons
Complete vertebrae

80
Q

What is lamprey larvae called?

A

Ammocoetes

81
Q

What type of metamorphosis do ammocoetes undergo?

A

Complete

82
Q

What type of feeding do lampreys have?

A

Parasitic

Some don’t feed- survive only a few weeks to breed

83
Q

What 4 features characterize vertebrates?

A
  • Rigid internal skeleton
  • Anterior skull with large brain
  • Internal organs suspended in coelom
  • Well developed circulatory system with contracting ventral heart
84
Q

What names is given to fish who evolved jaws via modification of the skeletal arches that supported the gills?

A

Gnathostomes

85
Q

What are the advantages of jaws?

A

Improve feeding efficiency- particularly when teeth evolved

86
Q

What do fins do for fish?

A

Stabilize their position in water

Propel them through water

87
Q

What fins do most fish have?

A

Pair of pectoral fins behind gill slits
Pair of pelvic fins anterior to pelvic region
Median dorsal and anal fins stabilize the fish as it moves and provide propulsion

88
Q

What fins help fish propel and turn rapidly?

A

Caudal fins

89
Q

What group of finned fish became abundant during the Devonian period and includes sharks, skates and rays?

A

Chondrichthyans

90
Q

What do chondrichthyans and chimeras have there skeletons composed from?

A

Catillage

91
Q

How do sharks move forwards?

A

Lateral undulations of their bodies and caudal fins

92
Q

How do skates and rays move forwards?

A

Vertical undulations of enlarged pectoral fins

93
Q

Give an example of cartilagenous fishes migrating into freshwater.

A

Stingrays were found in a rive system of South America.

94
Q

Where do chimeras live?

A

Deep-sea or cold waters

95
Q

In some early fish, what supplemented gas exchange function of the gills?

A

Gas-filled sacs

96
Q

What did gas-filled sacs in early fish enable?

A

Fish to live where oxygen was periodically in short supply (such as freshwater environments)

97
Q

What did lung-like sacs evolve into?

A

Swim bladders-organs of buoyancy

98
Q

What skeletons do ray-finned fish have?

A

Internal skeletons of calcified, rigid bone

99
Q

What do the gills of ray-finned fish open into?

A

A single chamber called an operculum

100
Q

What does movement of the operculum do?

A

Improves flow of water over the gills

101
Q

What do ray-finned fish eat?

A

Exploit nearly all types of aquatic food

102
Q

Many ray-finned fish are solitary, however, in open water they form aggregations called…

A

schools

103
Q

What did the evolution of lung-like sacs set stage for?

A

Evolution of land animals

104
Q

What enabled some fish to support themselves in shallow water and later move to land?

A

Changes in structure of fins

Ecology and diversity (17 decks)

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