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Invertebrates > Intro to Ecdysozoa Lecture 13 > Flashcards

Intro to Ecdysozoa Lecture 13 Flashcards

1
Q

support structure in Ecdysozoans

A

Exoskeleton

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2
Q

why is exoskeleton important

A
  • barrier to desiccation
    protection
    shape of animal
    frame for muscle attachment
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3
Q

features of Ecdysozoa

A

periodic molting (Ecdysis)
three layered cuticle
lack cilia for locomotion
amoebid sperm

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4
Q

Cycloneuralia (5) within Ecdysozoans

A 
Priapulida
Kinorhyncha
Loricifera 
Nematomorpha
Nematoda 
(named for position of brain around the pharynx)
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5
Q

Molting (Ecdysis)

A

periodic replacement of exoskeleton (believed to have only evolved once)

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6
Q

cuticle layers (3)

A

epicuticle (outside)- thin protein
exocuticle- protein, calcium, chitin
endocuticle (inside)- thick calcium, thick membranous layer
(secreted by epidermis)

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7
Q

Process of Ecdysis (3 steps)

A
  1. epidermis undergoes round of cell division and separates from exoskeleton (apolysis)
  2. new exoskeleton is secreted by epidermis, remains soft until old cuticle is shed
  3. new cuticle expands and hardens
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8
Q

Cycloneuralia also known as Introverta

A

spiny retractable proboscis (introvert) present in all phyla

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9
Q

Nematoida

A

Nematoda and Nematomorpha

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10
Q

traits of Nematoida

A

cuticle made of collagen
reduction of circular muscles
epidermal longitudinal nerve cords
amoebid sperm (tailless)

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11
Q

Nematodes

A

ecto and endoparasites of crops, animals and humans

impermeable cuticles good for parasitic nematodes

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12
Q

most common nematode parasite?

A

Pinworm

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13
Q

Cryptobiosis

A

Suspension of life processes in situations of unfavorable conditions into resistant states (nematodes, rotifers and tardigrades)

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14
Q

The model Nematode?

A

C. elegans

  • soils, in temperate regions
  • first multi-celled animal to have its genome completely sequenced
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15
Q

Nematode bauplan

A

adult nematodes have 1,000 somatic cells
tube within a tube (mouth at anterior extends back to the anus)
lack circulatory or respiratory systems

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16
Q

free-living vs parasitic forms

A

4 molts of the cuticle during growth

complicated lifestyle, usually with several different hosts

17
Q

Human diseases caused by Nematodes

A

Elephantiasis (filarial nematodes)
African river blindness
Hook worms and Whip worms

18
Q

One host parasites

A

Intestinal roundworm
Hook worm
Whipworm

19
Q

Two host parasites

A

Blood-sucking insect acts as intermediate host
Heartworm
Guinea worm

20
Q

How to get rid of parasites?

A

Finding out the specifics of the different molting processes in the parasitic nematodes and disrupting some stage of molting

21
Q

molting in nematodes

A

Relatively little is known about molting in nematodes, but making comparisons to molting in Arthropods may uncover aspects that constrain molting

22
Q

Difficulties in Nematodes and Arthropods

A

hard to connect similar underlying control of molting in both
Nematodes lack key enzymes (sterols)
cuticle is collagen rather than chitin
enzymatic cascade that mediates release of exoskeleton in nematodes may be distinct from arthropods

23
Q

Altering molting

A

Determine what genes are responsible for molting and inactivate them, killing the parasite and not affecting the host (RNA interference)

24
Q

Regulation of molting in Nematodes and Arthropods

A

Master regulators of molting may function in similar systems between the two
regulation of molting is conserved in Arthropods
(supports hyp that molting only evolved once)

25
Q

Nematomorpha

A 
horsetail worms 
very long and slender
terrestrial and fw
single pseudocoelom
lack of circular muscles 
Semi-parasitic (Larvae parasitic in insects, adults free-living in fw)
26
Q

Scalidophora or Cephalorhyncha

A

Kinorhyncha
Priapulida
Loricifera

27
Q

Priapulida

A
  • bottom dwelling, predatory worm
    large spiny eversible head end (introvert)
    distinctive plumose caudal appendage in some
    few species, but common in Cambrian Sea and fossils well known
    Large pseudocoelom
28
Q

Loricifera

A

recently discovered
occupy interstitial marine shell gravel, and deeper sediments (annoxic environments)
very tiny

29
Q

Bauplan of Loricifera

A 
Head region
Trunk region (6 plates that compose lorica)
Neck region (between head and trunk)
withdraw head into neck and both into trunk
30
Q

Scalids

A

spine on the head region that stick out protectively when head is extended and face outwards when head is withdrawn

31
Q

Kinorhyncha

A

sediment dwellers in global oceans
head, neck and trunk
Trunk has 11 segments called (zonites) with a single dorsal plate (tergite) and two ventral plates (sternites)
head retracted into trunk (introvert)
mouth surrounded by spines called stylets

Invertebrates (6 decks)

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