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fall semester 2024-25 LSSU > Unit 7: Chordates > Flashcards

Unit 7: Chordates Flashcards

1
Q

5 Characteristics: Notochord

A

Between the digestive tube and nerve cord
* Replaced by vertebral column in craniates

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2
Q

5 Characteristics: Dorsal hallow nerve cord

A

Derived from endoderm

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3
Q

5 Characteristics: Pharyngeal slits

A

openings in pharynx
– allow H2O out of mouth after feeding

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4
Q

5 Characteristics: Endostyle/thyroid gland

A

ciliated mucous producing tissue on
floor of the pharynx – produces similar substance to thyroid hormone

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5
Q

5 Characteristics: Post-anal tail

A

locomotion for fish, balance in some terrestrial species
* Vestigial coccyx aids in balance while sitting in humans

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6
Q

Non-vertebrate Chordate Groups: Two Invert Clades: Cephalochordata

A

– Lancets – retain 5 characteristics into adulthood
* Fossil representatives from Cambrian (500 MYA)
* Few cm blade-like shaped body, live in sand of warm/tropical seas
*H2O in mouth, exits pharyngeal slits that filter food particles, trapped food particles
caught by endostyle, carried to the gut.
* Dioecious

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7
Q

Non-vertebrate Chordate Groups: Two Invert Clades: Urochordata

A

– Tunicates – 1,600 sp. –
* only Pharyngeal slits and endostyle as adults
* Hermaphrodites (serial in some cases)
* Single or colonial filter feeders

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8
Q

Cranium

A

Bony, cartilaginous, or fibrous structure surrounding brain, jaw and facial bones

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9
Q

Craniata

A

includes all vertebrates, presence of cranium

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10
Q

Contain a vertebrae

A

series of separate, irregularly shaped bones joined to form a backbone
* Initially form in segments around notochord – but replace it in adults
* Notochord becomes nucleus pulposus – discs between vertebrae

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11
Q

how many craniata

A

62,000 species described

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12
Q

Agnatha

A

jawless vertebrates

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13
Q

Gnathostomes

A

jawed vertebrates

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14
Q

Superclass Agnatha

A

Monophyletic group

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15
Q

Myxini

A
  • 70 sp. – Hagfishes – all marine
  • Almost blind, sensory barbules near mouth locate prey
  • Unique slime glands on the skin
  • Cartilaginous skull, fibrous & cartilaginous skeleton
  • Notochord length of body – major structural support
  • Not replaced by spinal column = sister clade to vertebrates
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16
Q

Petromyzontidae

A
  • 40 sp – Lamprey – Marine and Freshwater
  • All spawn in freshwater
  • Eye muscles, true cerebellum, vertebral elements
  • One of earliest divergences from vertebrate*
  • Suspension-feeding juveniles
  • Adults may be parasitic
  • Rasping tongue
17
Q

Gnathostomes

A
  • True jaws & paired fins
  • From 1st set of gill arches ** ON TEST
  • Chondrichthyes – cartilaginous skeletons
  • Osteichthyes – Bony skeleton
    Actinopterygii – ray-finned fishes
    Sarcopterygii – Lobe-finned fishes
18
Q

Chondrichthyes

A
  • 370 MYA – today 1,000 sp – sharks, skates, rays, sawfishes
  • Paired fins, cartilage skeleton
  • Sensitive to vibrations and electrical currents:

Ampullae of Lorenzini – Sharks – electromagnetic fields produced by all living things
Lateral line – detect movement and vibration analogous to hearing in terrestrial vertebrates

19
Q

Sexual reproduction – sharks

A
  • internal fertilization (sharks – can be oviviviparous (hatch from egg while in uterus))
  • Mermaid’s purse – oviparous (egg-laying)
  • Hammerheads & Tiger sharks - viviparous (live-bearing)
20
Q

Rays and Skates

A
  • 500 sp
  • Flattened bodies, pectoral fins fused to the head
  • Gill slits on the ventral surface
21
Q

Amphibian Characteristics

A
  • 4 limbs (Caecilians – evolutionary reversal)
  • Moist, permeable skin
  • Respiration through the skin, buccal cavity, lungs
  • All carnivores and have teeth
  • Vomerineteethinroofofmouth
  • Image-forming eyes and colour vision
  • Ears with extra bone (operculum) in the ear
22
Q

Osteichthyes

A
  • 30,000 sp. Most numerous vertebrates
  • Ossified skeleton
  • Gills, swim bladder, lateral line
  • Actinopterygii (Ray-finned fishes) – the most numerous group of fish
  • Tuna, Bass, Trout…slender bones that support fins
  • Sarcopterygii (lobe-finned fishes)
  • Precursor to tetrapod limbs
    -Coelacanths alive today
23
Q

Amphibian Evolution: First tetrapods

A

– 400 MYA
* Evolved from lobe-finned fishes
* Transition to breathing air and moving on land = 50 MY

24
Q

Amphibian Evolution: Devonian

A

Early aquatic tetrapods in Devonian
* Aquatic – body not supported out of water

25
Q

Amphibian Evolution: Carboniferous

A

moved to land with few predators/competitors

26
Q

Modern Amphibians

A

6,770 sp in three clades of subclass Lissamphibia
* Urodela, Anura, Apoda

27
Q

Urodela

A

– Salamanders (620 sp)
* Movement through lateral undulation
* No lungs or primitive lungs, some gills and lungs
* Reproduction - courtship, spermatophore, oviparous, eggs in water (sperm packets)
* Metamorphosis before hatching

28
Q

Anura

A

Frogs & Toads – 5,965 sp. “no tail”
* Limbs adapted for jumping
* Some skin glands modified for toxin release
* Reproduction – external fertilization (female egg, male fertilizes)
* Parental care varied – none to carrying tadpoles/eggs on back
* Metamorphosis after hatching

29
Q

Apoda

A

Caecilians – 185 sp.
No limbs, evolved from limbed ancestor
* Resemble earthworm – with teeth and jaws * Internal fertilization, oviparous or viviparous

30
Q

Reptiles: Characteristics of Amniotes

A
  • Terrestrially adapted egg – Amniotic Egg *breathes!!
  • Blood vessels in the yolk sac – T-port nutrients to the embryo
  • Chorion – O2 & CO2 exchange – embryo and eggs external environment
  • Allantois – Stores N – wastes, also facilitates respiration
  • Amnion – protects the embryo from mechanical shock – supports hydration

The extra-embryonic membranes have various functions

31
Q

Evolution of Amniotes

A
  • Early tetrapod ancestor 340 MYA – 2 main lineages
    Synapsids – Therapsids – mammals evolved from
    Sauropsids: - Anapsids. -Diapsids (gave rise to reptiles)
  • Temporal fenestrae – post-orbital openings in the skull:
    Anapsids – no fenestrae
    Synapsids – 1 fenestrae
    Diapsids – 2 fenestrae
32
Q

Diapsids

A

Diverged into Archosauromorpha & Lepidosauromorpha

  • Archosaurs (ancient lizard form) – crocodilians, ichthyosaurs, pterosaurs, dinosaurs, birds “WHICH GROUP DOES BIRD/CROC BELONG TO”**
  • Lepidosaurs (scaly lizard form) – lizards, snakes, tuataras
33
Q

Characteristics of Reptiles

A
  • Tetrapods, amniotic eggs (some oviviviparous, some viviparous)
  • Scaly skin – rich in Keratin & Waxy lipids
  • Ventilation of lungs with muscles
  • Ectothermic:
    Crocodilians – regional endotherms (thoracic temps, pretty constant)
    Can survive on about 10% energy of comparable endotherm**
  • Burmation – metabolism slowed in cold temps
34
Q

Evolution of Reptiles

A
  • Archosaurs give rise to Dinosaurs:
    Saurischia (lizard-hipped)
    Ornithischia (bird-hipped)
  • Archosaurs give rise to Pterosaurs:
    More than 200 sp described – aerial
    100 sp terrestrial
  • Age of dinosaurs ended 65 MYA
35
Q

Modern Reptiles: Corcodilia

A

Middle Triassic – alligators, crocodiles, gharials, caimans
*Fresh and saltwater of Africa, Australia, Asia, South America, southern North America

36
Q

Modern Reptiles: Sphenodontia

A

Early mesozoic - Two species today – tautara

37
Q

Modern Reptiles: Squamata

A

Late Permian – Lizards (6,000 sp) and Snakes (3,600 sp)
* Snakes– specialized jaw in snakes– 8 rotational joints
* Snakes–single lung (long slender body) * Venomglands
* No eyelids–but transparent scale

38
Q
A

fall semester 2024-25 LSSU (9 decks)

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