Chapter 23: Chordates Flashcards Preview

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Flashcards in Chapter 23: Chordates Deck (46)
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0
Q

What are the five hallmark chordate characteristics?

A
  1. Dorsal tubular nerve cord
  2. Notochord
  3. Pharyngeal slits
  4. Endostyle (thyroid gland)
  5. Postanal tail
1
Q

What is a notochord???

A
  • rodlike, semirigid tissue enclosed in a sheath
  • in most cases it extends the length of the body lying between the gut and the NS
  • stiffens body and provides skeletal scaffolding for the attachment of swimming muscles.
2
Q

What six things do chordates have in common with invertebrates?

A
  1. Bilateral symmetry
  2. Anteriorposterior axis
  3. Coelom
  4. Tube- within- a- tube body plan
  5. Metamerism
  6. Cephalization
3
Q

What is the difference between Protochordata and Vertebrata?

A
  • Vertebrata= have skulls
4
Q

What are vertebrates divided into? (2)

A
  • Agnatha (Jawless)

- Gnathostomata ( have jaws)

5
Q

Vertebrates can be further divided into two other groups aside from having jaws or not. What are they?

A
  • Amniota - having an amnion

- Anamniota - lacking an amnion

6
Q

Gnathostomata can be subdivided into what? (2)

A
  • Pisces: with fins

- Tetrapoda: two pairs of limbs

7
Q

Notochord:

  • It is always found at some _____stage
  • It is the first part of the _____ to appear in the embryo
  • What attaches to the notochord?
  • Can bend without ____ and permits ___.
  • How persistent is it in protochordates and jawless vertebrates?
A
  • embryonic
  • endoskeleton
  • muscles
  • shortening, undulation (movement to alternating sides)
8
Q

In vertebrates:

- A series of what form from mesenchymal cells derived from blocks of mesodermal cells lateral to the notochord

A
  • cartilaginous or bony vertebrae
9
Q

In most vertebrates:

- The notochord is replaced by what?Are there any remnants ?

A
  • vertebrae

- remnants may persist between or within vertebrae

10
Q

Five Hallmark Characteristics:

  1. Dorsal Tubular Nerve Cord
    - In most invertebrate phyla the nerve cord is ___ and ___ to the digestive tract.
    - In chordates it ___ to the digestive tract.
    - The anterior end of the tubular nerve cord enlarges to form what?
    - How is it produced in embryo
A
  • solid, ventral
  • dorsal
  • brain
  • by infolding of ectodermal cells on the dorsal side of the body
11
Q

Five Hallmark Characteristics:

  1. Pharyngeal Pouches and Slits
    - Pharyngeal slits lead from ____ to ____.
    - How are they formed?
A
  • pharyngeal cavity, to the outside

- formed via inpocketing of the ectoderm and the evagination of endoderm of the pharynx.

12
Q

Five Hallmark Characteristics:
2. Pharyngeal Pouches and Slits
L> In aquatic Chordates ?

A
  • 2 pockets break through to from pharyngeal slits
13
Q

Five Hallmark Characteristics:
2. Pharyngeal Pouches and Slits
L> In amniotes ?

A
  • pockets may not break through and only pouches are formed.
14
Q
Five Hallmark Characteristics:
2. Pharyngeal Pouches and Slits
L> Tetrapods?
- what do they give rise to? (4)
- Fishes added a \_\_\_\_ with thin gas permeable walls which led to what?
A
  • pharyngeal pouches give rise to a variety of structures, including the Eustachian tube, middle ear cavity, tonsils and parathyroid glands.
  • capillary network
    L> evolution of gills
15
Q

Five Hallmark Characteristics:

4. Endostyle or Thyroid gland

A
  • the Endostyle or its derivative the thyroid gland are found in all chordates.
16
Q

Five Hallmark Characteristics:

  1. Postanal tail
    - what did this do for tunicates and amphioxus?
    - fishes?
A
  • this tail and musculature provided motlily for larval tunicates and amphioxus to swim.
  • Efficiency increased in fishes but became smaller or vestigial in later lineages.
17
Q

Adaptations that guided Vertebrate Evolution:
- Early vertebrates:
L> they were much larger and more active than protochordates. What changes did they go through to meet there demands that came along with their size and metabolic rate?

A
  • modifications of skeletal structures and muscles permitting increased speed and mobility.
  • higher activity level and size required structures specialized in location, capture, and digestion of food and adaptations designed to support a high metabolic rate.
18
Q

Musculoskeletal Modifications??

- most vertebrates possess what for a skeleton?

A

-endoskeleton of cartilage or bone and an exoskeleton
L> The endoskeleton permits almost unlimited body size with much greater economy of building materials.
-

19
Q

Musculoskeletal Modifications??

- What do neural spines provide?

A
  • more area for attachment of segmented muscles
20
Q

Musculoskeletal Modifications?

- what are myomeres?

A
  • segmented body muscles that are W-shaped…they changed from the ancestral chordates which had V-shaped muscles.
21
Q

Musculoskeletal Modifications?

- in terms of fins what are unique to vertebrates?

A
  • fin rays of dermal origin in fins which aid in swimming
22
Q

Musculoskeletal Modifications?

- What was the endoskeleton initially proposed to be composed of?

A
  • cartilage and later bone
23
Q

Musculoskeletal Modifications?
-The endoskeleton of living hagfish, lampreys, sharks, and even some bony fishes like surgeons are mostly composed of what?

A
  • cartilage
24
Q

Musculoskeletal Modifications?

- which is more structurally strong, cartilage or bone?Explain why you chose your answer as well!

A
  • bone, it is ideal for muscle attachment in areas of high mechanical stress.
25
Q

Musculoskeletal Modifications?

- Why did Bone evolve from cartilage?

A
  • means of mineral regulation
  • phosphorous and calcium are used for many physiological processes.
  • especially in high demand for organisms with high metabolic rates.
26
Q

Physiology:

-What were all modified to meet increased metabolic demand? (4)

A
  • digestive, circulatory, respiratory and excretory systems
27
Q

Physiology:

-What evolved as a filter feeding device in early chordates?

A
  • perforated pharynx
28
Q

Physiology:

- How does a perforated pharynx work?

A
  • water with suspended food particles are drawn through the pharynx via ciliary action and trapped by mucus secreted by the endostyle.
29
Q

Physiology:

- In larger predatory vertebrates what was the pharynx modified into?

A
  • muscular apparatus that pumped water through pharynx
30
Q

Physiology:

-What caused the shift from the pharynx playing a role in feeding to primarily gas exchange?

A
  • origin of highly vascularized gills
31
Q

Physiology:

-To manage increased ingestion of food what modifications occurred in vertebrates?

A
  • gut shifted movement of food by ciliary action to muscular action
  • accessory digestive glands, the liver and pancreas produced secretions to aid in digestion.
32
Q

Physiology:

- The transport of nutrients gases and other substances was enhanced by what? (2)

A
  • Ventral 3 chambered heart
    L> Sinus venosus, Atrium, Ventricle
  • Erythrocytes containing hemoglobin
33
Q

Physiology:

- Vertebrates possess paired glomerular kidneys for what function?

A
  • remove metabolic waste products and regulate body fluid composition
34
Q

New head, brain and sensory systems (vertebrates):

-What caused the need for new sensory, motor and integrative controls?

A
  • shift from filter feeding to active predation
35
Q

New head, brain and sensory systems (vertebrates):

- The anterior end of the nerve cord enlarged as what?Containing what ? What is it protected by?

A
  • tripartite brain
    L> Forebrain, midbrain, hindbrain
    *brain is protected by cartilaginous or bony cranium
36
Q

New head, brain and sensory systems (vertebrates):

  • What are they three functions that evolved for the paired special sense organs?
  • what other receptors evolved? (4)
A
  • vision, equilibrium and sound evolved

- mechanoreceptors, chemoreceptors, electroreceptors, and olfactory receptors

37
Q

Ostracoderms:

  • Until recently, these were considered what ?
  • What time period were they from?
  • Physical description?
  • What discovery led to dating vertebrates back to a different time period?
A
  • earliest known verts
  • late cambrian
  • small, heavily armoured, jawless and lacked paired fins.
  • in the last 10 years, many 530 million year old fossils were discovered belonging to one or two fishlike verts…pushing the origin of verts to at least the early Cambrian period.
38
Q

Ostracoderms continued:

- The 530 million year old fossils showed many vertebrate characteristics such as what?

A
  • heart, paired eyes, otic capsules and rudimentary vertebrae.
39
Q

Earliest Ostracoderms:

  • Characteristics?
  • What are they considered to be? ex?
A
  • equipped with bone in dermis
  • lacked pair fins that later fishes used for stability
  • Not considered a natural evolutionary assemblage but a convenient category to describe several groups of heavily armoured extinct jawless fishes, ex: Heterostracans.
40
Q

What are cyclostomes?

A
  • living agnathans, lampreys and hagfishes
41
Q

Are Gnathostomes a monophyletic, polyphyletic or paraphyletic ?

A
  • monophyletic

L> presence of jaws is a derived character state shared by all jawed fishes and tetrapods.

42
Q

How does evidence indicate jaws arose?

  • modification of what?
  • in terms of derivation how are these bones different from others?
A
  • via modification of 1st two cartilaginous gill arches
    L> both gill arches and jaws form from upper and lower bars that bend forward and are hinged
  • both are derived from neural crest cells rather than from mesodermal tissues as are most bones
43
Q

The mandibular arch may have first become enlarged to assist what?

A
  • gill ventilation

L> perhaps to meet increasing metabolic demands of early verts

44
Q

When did Placoderms appear?

A
  • Devonian , were heavily armoured
45
Q

Acanthodians are what?

A
  • included in a clade that underwent a great radiation into bony fishes that dominate waters today

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