Lecture 18 Flashcards

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1
Q

Ectdysozoa characteristics

A

moult cuticle in order to grow (ectdysis)

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2
Q

ectdysis

A

entire cuticle shed at once

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3
Q

4 main phyla of ectdysozoa

A
  1. onychophora (110)
  2. tardigrada (800)
  3. nematoda (25 000)
  4. arthropoda (1 million)
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4
Q

epidermis

A

below cuticle, living cells that secrete substances that become cuticle

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5
Q

3 layers of cuticle

A
  1. epicuticle (includes layer of waxes)
  2. exocuticle
  3. endocuticle
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6
Q

sclerites

A

hardened plate-shaped regions

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7
Q

moulting 10 steps

A
  1. apolysis
  2. inactive moulting fluid secreted by epidermis
  3. thin protective layer deposited between moulting fluid and epidermis
  4. enzymes activated, endocuticle digested
  5. new undifferentiated layer of cuticle deposited under protective layer (greater surface area, wrinkled)
  6. moulting fluid reabsorbed
  7. epicuticle laid down
  8. old exocuticle and epicuticle moulted (ectdysis)
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8
Q

moulting 10 steps

A
  1. apolysis
  2. inactive moulting fluid secreted by epidermis
  3. thin protective layer deposited between moulting fluid and epidermis
  4. enzymes activated, endocuticle digested
  5. new undifferentiated layer of cuticle deposited under protective layer (greater surface area, wrinkled)
  6. moulting fluid reabsorbed
  7. epicuticle laid down
  8. old exocuticle and epicuticle moulted (ectdysis - may swallow water or air)
  9. new cuticle expanded
  10. exocuticle sclerotized
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9
Q

phylum onychophora

A

velvet worms, tropical terrestrial

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10
Q

phylum onychophora

A

velvet worms, tropical terrestrial, Cambrian ancestors were marine

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11
Q

haemocoel

A

no closed blood vessels, organs bathed in haemolymph, pumped by open-ended tubelike heart

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12
Q

onychophora morphology

A
  1. soft-bodied, segmented
  2. lobopods
  3. little cephalization
  4. haemocoel
  5. single pair of sensory antennae on head
  6. exchange gases using tracheal system
    7.
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13
Q

onychophora morphology

A
  1. soft-bodied, segmented
  2. lobopods
  3. little cephalization
  4. haemocoel
  5. single pair of sensory antennae on head
  6. exchange gases using tracheal system
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14
Q

tracheal system

A

stigmata lead to tracheae which terminate in many fine tubes, O2 and CO2 diffuse

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15
Q

stigmata aka spiracles

A

openings in sides of onychophoran body

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16
Q

tracheae

A

large-bore tubes

17
Q

onychophora feeding

A

all predators, capture prey by shooting glue from glue glands next to mouth

18
Q

onychophora reproduction

A
  1. separate sexes
  2. normal copulation or hypodermic insemination
  3. females oviparous, ovoviviparous, or viviparous
19
Q

hypodermic insemination

A

spermatophore placed on female’s skin, digests through into haemocoel, sperm released and crawl to eggs

20
Q

oviparous

A

lay eggs that undergo embryonic development outside female’s body

21
Q

ovoviviparous

A

eggs retained in mother’s body where the young develop, nourished by egg yolk, and hatch inside the mother or immediately after eggs are laid

22
Q

viviparous

A

young not in eggs undergo development inside mother where they receive nutrients, typically via a placental connection to mother’s tissues

23
Q

phylum tardigrada

A

water bears, most freshwater some marine,

24
Q

tardigrada morphology

A
  1. 4 pairs of claw-tipped lobopod limbs, move by stepping slowly
  2. no antennae or gas exchange system
  3. periodically moult
  4. able to enter a state of suspended animation in response to drying of habitat
25
Q

phylum nematoda

A

roundworms, threadworms, morphologically tedious, most free-living in organic substrates, many parasites, medically important

26
Q

nematoda morphology

A
  1. no segmentation, appendages, nor eyes
  2. slightly blunt at one end, slightly pointy at the other
  3. do moult
  4. pseudocoelomate
27
Q

nematode reproduction

A
  1. separate sexes, some hermaphrodites
  2. sperm transferred directly by intromission
  3. eutelic
28
Q

intromission

A

(male inserts sperm-transferring structure inside female’s genital opening

29
Q

eutelic

A

post-embryonic growth occurs by each cell growing, not by addition of cells

30
Q

Caenorhabditis elegans

A

nematode that is model organism for studying development, can knock out one cell from older embryo
and see what is missing in adult (eutelic)

31
Q

phylum arthropoda

A

most species rich, most ecologically important for decomposition and pollination

32
Q

arthropod morphology

A
  1. jointed limbs
  2. sclerotized cuticle made out of chitin acts as exoskeleton
  3. segmented
  4. well cephalized
  5. tagmata in addition to head
33
Q

sclerotized exoskeleton

A

provides support and a rigid surface for muscles

to attach to, sometimes incorporates minerals

34
Q

tagma

A

collection of adjacent segments specialized for some function

35
Q

5 main groups of arthropods

A
  1. trilobita
  2. chelicerata
  3. myriapoda
  4. crustacea
  5. hexapoda