Lesson 3 - Protochordates and the Origin of Craniates Flashcards
1
Q
what is present in protochordates
A
- bilateral symmetry
- pharyngeal slits
- notochord
- dorsal hollow CNS
- postanal tail
- endostyle
2
Q
- had bony plates and scales (armored fishes)
- jawless vertebrates
- small bony scales fitted tightly where there are no scales
A
ostracoderms
3
Q
when did ostracoderms occur
A
late Cambrian period through the Devonian
(400-525 million years ago)
4
Q
primitive fish that have many similarities to living hagfish and are the oldest vertebrates (530 my) ever found
A
- Myllokunmingia fengjiaoa
- Haikouichthys ercaicunensis
5
Q
when did Myllokunmingia fengjiaoa
and Haikouichthys ercaicunensis live
A
530 million years ago
6
Q
- literally the ‘Chinese eel of good fortune’
- earliest known chrodate
- thought to be a fossil relative of modern lancelets
A
Cathaymyrus diadexus
7
Q
proposed the establishment of Phylum Chordata in 1874
A
Ernst Haeckel
8
Q
Subphylums under Phylum Chordata
A
- Urochordata
- Cephalochordata
- Craniata
9
Q
subset of the larger group of animalia and share common features in development
A
basal deuterostomes
10
Q
- presence of calcium carbonate skeleton
- presence of a secondary radial symmetry except in the most basal members
- Cambrian to present
A
Echinoderms
11
Q
example of echinoderms
A
- starfish
- sea urchins
- sea cucumbers
- sea daisies
- crinoids
12
Q
- acorn worms
- marine organisms that live in the mud under shallow waters
- fragile when handled
- 1.5 meters
- with invertabrate and chordate features
A
Hemichordates
13
Q
added Hemichordates (acorn worms) to the Phylum Chordata
A
Bateson
14
Q
why did Bateson add acorn worms to the Phylum Chordata in 1884
A
- dorsal, hollow nervous system
- gill slits
- short diverticulum of the gut (stomochord)
15
Q
- short diverticulum of the gut
- not homologous with notochord
A
stomochord
16
Q
- marine chordates
- notochord is confined to the locomotor tail of the free-living larval stage and lost during metamorphosis into sessile adults
- enclosed within a delicate, nonliving, and colored transparent tunic
- filter feeders
- posses pharyngeal slits
A
Urochordata
17
Q
urochordata are enclosed within a delicate, nonliving, and colored transparent __
A
tunic
18
Q
- sea squirts
- solitary or colonial populations
- larvae, have fleeting existence and do not feed (subsist on nutrients stored in the tissues)
A
Ascidians
19
Q
three unequal regions of Hemichordates
A
- proboscis
- collar
- trunk
20
Q
parts of the Ascidian larva
A
- mouth
- pharyngeal slit
- atriopore
21
Q
- external opening through which water exits the body after passing through the pharyngeal slits
- plays a key role in their filter-feeding system and respiratory process
A
atriopore
22
Q
Features of the Subphylum Cephalochordata
A
- notochord
- dorsal, hollow nervous system
- pharyngeal gill slits
- ‘circulatory’ system - vertebrate pattern with pumping vessels but no heart
23
Q
where is the locomotor musculature of subphylum cephalochordata found
A
muscles segments lie just under the skin
24
Q
subphylum cephalochordata :
__ extend the entire length of the organism (locomotor muscle)
A
myomeres
25
skin of subphylum cephalochordata
single layer of epidermis
26
respiration of subphylum cephalochordata
cutaneous respiration
27
subphylum cephalochordata
- opens into the atrium which surrounds the pharynx laterally and ventrally
- water that enters here is another source of oxygen
pharyngeal slits
28
how many pharyngeal slits are present in adult organisms of subphylum cephalochordata
60
29
Pathway of water in subphylum cephalochordata
pharynx --> atrium --> atriopore
30
- extends from tip, to the rostrum, to the tip of the tails
- muscular disc arranged like a long roll of coins separated by fluid-filled spaces
- adaptation that facilitates burrowing in the sand
notochord
31
where does the notochord extend from and to in subphylum cephalochordata
tip to rostrum to tip of tails
32
skeletal structures of notochord in subphylum cephalochordata
fibrous rods that support
- pharyngeal bars
- buccall cirri
- mid-dorsal fin-like ridges
33
subphylum cephalochordata
- hollow brain and dorsal nerve cord containing a central canal lined with ependymal cells
- brain has two subdivisions
- with cranial nerves
- spinal nerves -- dorsal roots
nervous system and sense organs
34
surrounds the brain and spinal cord of subphylum cephalochordata
leptomeninx
35
- light sensitive and pigmented
- embedded within the ventrolateral walls of the spinal cord throughout its length
- consists of a receptor cell and caplike melanocyte
Ocellus
36
what are absent in subphylum cephalochordata
- retinas
- semicircular canals
- lateral-line organs
37
chemoreceptors of subphylum cephalochordata
- buccal cirri
- velar tentacles
- tail
- trunk
38
monitor the incurrent water stream
velar tentacles
39
what type of feeders are subphylum cephalochordata
filter feeders
40
create a steady flow of water through the mouth and into the pharynx
cilia
41
subphylum cephalochordata
- collective chamber of seawater
- laterally by oral hood, caudally by velum, perforated by the mouth, which opens into the pharynx
vestibule
42
subphylum cephalochordata
- covered with sticky mucus
- retrieves some of the heavier food particles which directs it to the mouth and pharynx
wheel organ
43
subphylum cephalochordata
- partially strain water as it enters the vestibule
- chemoreceptors monitor the food that enters
buccal cirri
44
pathway of food in subphylum cephalochordata
1. pharynx
2. epibranchial groove
3. midgut
4. midgut ring
5. hindgut or intestinal caecum
6. anus
45
digestive enzymes
midgut ring
46
digestive juices for digestion
hindgut or intestinal caecum
47
not prominent cavity in adult organisms in subphylum cephalochordata
coelom
48
color of blood in subphylum cephalochordata
colorless
- lacks blood cells, platelets, and other formed bodies
49
subphylum cephalochordata
- termination of venous system
- beginning of arteries
- not a pump
sinus venosus
50
subphylum cephalochordata
- cells that collect the metabolic wastes
cyrtopodocytes
51
subphylum cephalochordata
- footlike projections that make contact with an adjacent glomerulus
pedicels
52
subphylum cephalochordata
- collects fluid from a cluster of cyrtopodocytes and empty into the atrium
nephridial tubule
53
subphylum cephalochordata
- from cyrtopodocyte that propell tubulue fluids to the atrium
flagellum
54
pathway of the excretory system in subphylum cephalochordata
1. glomeruli
2. pedicels
3. cyrtopodocyte
4. microvillar strands
5. nephridial tubule
6. atrium
7. atriopore
55
subphylum cephalochordata
- bulge into the atrium into which sperm or egg are shed
- gametes are flushed into the sea via atriopore
gonads
56
subphylum cephalochordata are __ which means that ovaries and testes do not develop in the same individual
dioecious
57
Amphioxus (a) vs Craniate (c):
cephalization
C = present
A = absent
58
Amphioxus (a) vs Craniate (c):
paired sense organs
C = present
A = absent
59
Amphioxus (a) vs Craniate (c):
notochord
C = present
A = present, no vertebral column
60
Amphioxus (a) vs Craniate (c):
Pharyngeal slits
C = present
A = present, large in numbers and emptying into the atrium
61
Amphioxus (a) vs Craniate (c):
hollow CNA
C = present
A = present, brains lack major subdivisions
62
Amphioxus (a) vs Craniate (c):
segmented musculature
C = present
A = present, extend to tip of head
63
Amphioxus (a) vs Craniate (c):
two layered skin
C = present
A = present, epidermis one cell thick
64
Amphioxus (a) vs Craniate (c):
venous and arterial channels
C = present
A = present, no muscular heart
65
Amphioxus (a) vs Craniate (c):
coelom
C = present
A = present, restricted in adults
