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Origins of Biodiversity > Animals and Bilaterians > Flashcards

Animals and Bilaterians Flashcards

Lectures 11-14

1
Q

What are the modes of nutrition for plants, fungi and animals?

A

P - Autotrophs (photosynthesis)
F - Heterotrophs (growing on resource)
A - Heterotrophs (resource is digested)

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2
Q

What is the cell wall structure of plants, fungi and animals?

A

P - Cellulose
F - Chitin
A - none, held together via cellular matrix made of structural proteins like collagens. sheep have no walls. (sorry when you see this Dan its an inside joke)

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3
Q

Describe the stages of embryonic development for animals.

A
  • Zygote
  • Cleavage, continuously divides into blastula with blastocoel inside
  • Gastrulation occurs (bending in of one part of the cell), creating a gastrula.
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4
Q

Describe the layers of a gastrula.

A

Outer most layer: Blastocoel
Second/third layer: Endoderm, ectoderm
Middle: Archenteron
Cells where embryo is bent in: Blastopore

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5
Q

Does the embryo change size during this process?

A

No. It is fully reliant on its own resources and does not change size, only divides into more cells.

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6
Q

What gene dictates body plan? How?

A

Hox. Evolution of hox genes drives evolution by regulating batteries of downstream target genes, telling cells where they are meant to be and switching genes on/off.

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7
Q

What are the two periods that make up the Neoproterozoic era?

A

Cryogenian and Ediacaran period.

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8
Q

When was and what occurred in the Cryogenian Period?

A
  • 850-635 mya
  • No fossils known from this period
  • Chemical found in sediment suggest existence of sponge like metazoans
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9
Q

When was and what happened in the Ediacaran period?

A
  • 630-540 mya
  • Earliest fossil evidence
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10
Q

What went down in the Palaeozoic? When was it?

A
  • 540 to 250 mya
  • Cambrian explosion
  • Vertebrates moved onto land around 365 mya
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11
Q

What are the theories on the cause of the Cambrian explosion?

A
  • Emergence of predator/prey relationships forced hunters to become more efficient and prey to improve defences (shells etc)
  • Increase in oxygen levels led to higher metabolic rate
  • Evolution of hox gene
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12
Q

What and when was the Mesozoic era?

A
  • 250 to 65 mya
  • Began with Permian Triassic mass extinction
  • Dominated by reptiles but first small mammals were appearing
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13
Q

What and when was the Cenozoic era?

A
  • 65 mya to present
  • Began with mass extinction event (End Triassic)
  • Dominated by mammals and diversification
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14
Q

Describe the symmetry of animals.

A

Porifera - None
Cnidaria, Ctenophora - Radial
Everything else basically - Bilateral

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15
Q

What is the difference between diploblasts and triploblasts?

A

Diploblast: Two layers of tissue (Endoderm and ectoderm), includes cnidaria and Ctenophora.
Triploblast: Three layers of tissue (Endoderm, ectoderm, mesoderm which allows for tissue development), includes most others.

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16
Q

Describe the body cavities of different animals.

A

Within mesoderm: Annelids, molluscs, arthropods, echinoderms, chordates
Between mesoderm and endoderm: Roundworm
None: Flatworm

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17
Q

What is gastrulation?

A
  • Transforms single layered blastula into double layered gastrula, allowing true tissues to develop. Also allows gastrodermis (digestion) and epidermis (protection)
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18
Q

Describe hydrozoa.

A
  • Have both colonial polyp stage and medusa stage
  • Have gas filled air sacks called pneumatophores.
  • Able to submerge quickly via a siphon that allows for quick deflation.
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19
Q

What are hydrozoans 3 polyp types?

A

Dactylozooid: Catch prey, also for defence
Gonozooid: Reproduction
Gastrozooid: Feeding

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20
Q

Give a summary of Scyphozoa.

A

Jellyfish.

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21
Q

Give a summary of cubozoa.

A
  • Box jellyfish
  • Stinging shitheads (very poisonous)
  • Active predators with eyes that have cornea, retina and lens
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22
Q

Give a summary of Anthozoa.

A
  • Solitary sea anemones and corals
  • Symbiotic relationship with zooxanthella (protozoans) or zoochorella (algae)
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23
Q

Give a summary of Ctenophores.

A
  • Comb jellies
  • Rows of fused cilia for locomotion
  • Adhesive cells on tentacles for catching prey (called colloblasts)
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24
Q

What is a bilaterian?

A

Animals with bilateral symmetry.

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25
Q

What type of locomotion do bilaterians do?

A

Across environmental gradients, giving advantages in finding food, mates and avoiding predators over diploblasts which have no locomotion.

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26
Q

What is cephalisation?

A

Having a head in which sensory organs are concentrated.

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27
Q

What is secondary radial symmetry and which bilaterians possess it?

A

When during development they are bilaterian but throughout the rest of life they are radial. Sessile bilaterians do this (bryozoans, echinoderms, annelids)

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28
Q

What type of skeleton do bilaterians have? What is its properties?

A

Hydrostatic. Enclosed volume of incompressible fluid for support and to counteract muscles, well suited for aquatic habitats.

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29
Q

What muscle process do hydrostatic skeletons allow for?

A

Antagonistic effect of longitudinal and circular muscles.

30
Q

What is the common name for Platyhelminthes?

A

Flatworms.

31
Q

Give a summary of Platyhelminthes.

A
  • Triploblasts
  • Acoelomates (no internal, fluid-filled body cavity separating its body wall from its digestive tract).
  • Many are parasitic
  • Dorsoventrally flattened bodies
32
Q

Give a summary of Turbellaria.

A
  • Free living
  • Carnivores
  • Include planarians
33
Q

Give a summary of Planarians.

A
  • Asexual reproduction via architomy (body splits apart and forms a new one)
  • Sexual reproduction via hermaphrodites mating
  • Have eyespots
34
Q

What happens when you cut off too much of a worm?

A

It cannot regrow as it loses polarity. It is just a head, called a janus head.

35
Q

Give a summary of monogenea and Trematoda.

A
  • Parasites
  • Suckers for attachment
36
Q

Give a summary of Cestoda.

A
  • Tapeworms
  • Scolex (head) with hooks/suckers for attachment
  • Body made of small segments called proglottids, which each have sex organs
37
Q

Give a summary of Rotifera.

A
  • A phylum
  • Triploblasts with pseudocoelom that functions as a hydrostatic skeleton
  • Tiny (up to 2mm)
  • Actual gut with mouth (that has cilia crown) and anus
38
Q

Describe how Rotifers reproduce.

A
  • In favourable conditions only females reproduce asexually
  • In unfavourable conditions males fertilise eggs and embryos form which are capable of dormancy
  • Some groups haven’t produced males in 35 million years.
39
Q

What are protostomes?

A

Animals who’s mouth develop before the anus in during embryonic development.

40
Q

Which phyla fit into the group Lophotrocozoans?

A
  • Platyhelminthes
  • Rotifera
  • Ectoprocta (Bryozoans)
  • Braciopoda
  • Acanthocephala
  • Nemertea
  • Annelida
  • Mollusca
41
Q

What is a lophophore?

A

Crown of ciliated tentacles around the mouth used for filter feeding. These are sessile.

42
Q

Give a summary of braciopoda.

A
  • Marine lamp shells
  • Similar to clams but have dorsal/ventral shell halves rather than lateral
  • Convergent evolution
  • Anchored to substrate via pedicle
43
Q

Give a summary of Nemertea.

A
  • Ribbon worms
  • Active swimmers, can burrow into sand.
  • All predatory, have proboscis for hunting. This everts when circular muscles contract and fluid pressure increases.
44
Q

Give a summary of Annelids.

A
  • Segmented worms
  • Have chaetae (stiff bristle made of chitin)
  • Trochophore larvae
  • 2 cavities per segments, separated by mesentery. Segments separated by septae.
  • Nervous system has 1 ganglion per segment
45
Q

Describe polychaeta.

A
  • Clear head region
  • Each segment has burrowing parapodia and chaetae.
  • Burrow using retrograde waves of parapodia that alternate left and right.
  • Fan and Christmas tree worms
46
Q

Describe Oligochaeta.

A
  • Earthworms
  • No clear head but have chaetae
  • No parapodia, move via peristaltic crawling
47
Q

Describe Hirudinea.

A
  • Leeches
  • No chaetae, lack of segmentation
  • Blood suckers with blade like jaws and anaesthetic
48
Q

What are Ecdysozoa?

A

Animals that moult via ecdysis.

49
Q

Give a summary of Tardigrada.

A
  • Teeny tiny things that can live anywhere including space. Also ancient (350my)
50
Q

Give a summary of nematoda.

A
  • Unsegmented round worms
  • Are pseudocoelomates: fluid filled body cavity partially lined with mesoderm/
  • Feed on decomposing material/bacteria
  • Only longitudinal muscles (so they only thrash)
  • Usually hermaphrodites
  • Great biological control because they are specific parasites.
51
Q

Describe the internal characteristics of molluscs?

A
  • Protosomes
  • Have coeloms (cavity lined with mesoderm)
  • Blastopore (opening in archenteron and second opening formed later on to make a digestive tube)
52
Q

Describe the layers of a mollusc shell.

A

Top hard layer: Periostracum
Middle large layer: Ostracum
Iridescent layer at bottom: Nacre
Then mantle that secretes shell.

53
Q

What is the general rule of thumb for mollusc reproduction?

A

Most have separate sexes with gonads in their visceral mass. Most terrestrial snails are hermaphroditic.

54
Q

What does larval development in mollusc look like?

A
  • Ciliated larvae known as trochophore
  • Also found in annelids/other lophotrochozoans
  • Develop into specialised larvae in bivalves/gastropods
  • Cephalopods are an exception, having hatchlings which are just mini adults.
55
Q

Describe monoplacophora.

A
  • Meaning one plate
  • Segmented like worms and internal organs are duplicated in these segments
  • Only live in the deep
56
Q

Describe polyplacophora.

A
  • Meaning multiple plates (8)
  • Chitons
  • Use muscular foot to grip and creep over rocks. Eat by scraping algae off rocks using radula.
57
Q

What are the general characteristics of Gastropods?

A
  • Snails slugs etc
  • Move using rippling motion of foot, also feed using radula scraping. Few are predatory (cone)
  • Undergo torsion in which during development the visceral mass rotates 180 degrees.
58
Q

Describe the subclass Prosobranchia.

A
  • Most primitive gastropods
  • Have gills and operculum
  • Mantle extends into siphon to draw in water and ‘smelling’ (this or uses holes in shell like an abalone)
59
Q

Describe Opisthobranchia.

A
  • Sea hares and slugs
  • No shell, use chemical defence
  • no operculum and have external gas exchange structures.
60
Q

Describe Pulmonata.

A
  • no gills, air or water drawn into mantle
  • Usually no operculum
  • Pneumostome (external breathing pore)
61
Q

How are the shells of bivalves arranged?

A

2 valved hinged shell, hinged at the mid dorsal line.
- Closes via powerful adductor muscles

62
Q

Describe Bivalvia- their body and fertilisation.

A
  • Foot not for crawling as they are sedentary or burrowing.
  • No head or radula (filter feeders)
  • External fertilisation.
63
Q

What are the gills of bivalves known as? what is their function, and what other group share them?

A
  • Ctenidia
  • Traps fine particles in mucus to filter feed.
  • Also used for gas exchange.
  • Gastropods and bivalves use them too
64
Q

How do bivalves do gas exchange?

A

Water flows in the mantle cavity via the incurrent siphon, passes over gills (ctenidia) exits via excurrent siphon.

65
Q

Describe the sub class Lamellibranchia.

A
  • Most common bivalves (mussels, clams, scallops)
  • Two flow siphon
  • Teeth on shell for wood boring
66
Q

Give a general summary of cephalopods.

A
  • all marine and predatory
  • Well developed sensory organs such as eyes
  • High intelligence brain/nervous system
  • Have ctenidia.
  • Closed circulatory system
67
Q

What modifications to the basic mollusc body plan are seen in Cephalopods?

A
  • Foot modified into muscular siphon, parts of tentacles and head
  • Shell is reduced/absent apart from Nautilus
  • Siphon shoots out water when mantle cavity is contracted, causing fast movement.
  • Radula is specialised beak
68
Q

How do cephalopods reproduce?

A
  • Transferring sperm to egg via (hectocotylus) specialised arm
  • In some species males may use the arm to store the sperm, or will just wrench it off and give it to the female and regrow it.
69
Q

Describe sub class Nautiloids.

A
  • External shells that are segmented for buoyance, body is only in the last segment
70
Q

What are subclass Coleoidea and its orders?

A
  • Squids, cuttlefish and octopuses.
    Order: Sepioidea (cuttlefish)
    Order: Decapoda (Squid)
    Order: Octopoda

Origins of Biodiversity (9 decks)

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