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Biology 108 > Lecture 28 Craniates > Flashcards

Lecture 28 Craniates Flashcards

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1
Q

what is clade craniata?

A

animals in chordata with a head

  • skull of hard bone or cartilage
  • origin of head allowed coordination of more complex movement and feeding behaviours
  • marine, freshwater, terrestrial
  • most are vertebrates
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2
Q

what did ancestral chordates resemble?

A

lancelets

  • same hox genes that organize vertebrate brain expressed in lancelet’s simple nerve cord tip
  • genome sequencing suggests: genes associated with HEART AND THYROID COMMON TO ALL CHORDATES; genes assoc with transmission of nerve impulses UNIQUE TO VERTEBRATES
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3
Q

what are the 5 derived characteristics of craniates?

A
  1. two clusters of hox genes – non-craniates (lancelets and tunicates have
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4
Q

what are the 5 derived characteristics of craniates?

A
  1. two clusters of hox genes – non-craniates (lancelets and tunicates) have one cluster. Hox genes control the body plan of an embryo along the head-tail axis; determine the type of segment structures that will form
  2. Neural crest. Collection of cells near the dorsal margins of closing neural tube in embryo. Give rise to a variety of structures, including some of the bones and cartilage of skull
  3. endoskeleton and pronounced cephalization – brain encased in protective plates, endoskeleton is cartilage or bone, includes paired eyes and other sensory organs
  4. circulatory system modified. closed circulatory systems, including a heart with at least two chambers, hemoglobin in RBC, supports higher metabolisms
  5. embryonic pharyngeal clefts – develop into active organs –fxns associate with muscles and nerves – gill slits in aquatic species, parts of ear
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5
Q

what is the origin of craniates?

A
  • fossils from cambrian explosion document transition between non-craniate and craniate chordates
  • in other cambrian rocks – fossils of more advanced chordates
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6
Q

what are the basal craniates?

A
  • extant classes that lack jaws
  • hagfishes and lampreys - agnathans
  • lack teeth and paired limbs (fins)
  • extant agnathans look rather like eels - long flexible tubular bodies, no paired fins, paraphyletic group
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7
Q

what are hagfishes?

A

agnathans - class myxini

  • most basal group
  • only known living animals that have a skull but no vertebral column
  • cartilaginous cranium; no jaws
  • ## well developed notochord: axial rod of cartilage
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8
Q

what are hagfishes?

A

agnathans - class myxini

  • most basal group
  • only known living animals that have a skull but no vertebral column
  • cartilaginous cranium; no jaws
  • well developed notochord: axial rod of cartilage
  • have a small brain, lensless eyespots, and tooth-like structures composed of keratin
  • scavengers
  • exude fibrous slime from body when attacked
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9
Q

what is subphylum vertebrata?

A
  • craniates that have a backbone/ vertebral column: chain of skeletal elements surrounding and protecting the nerve cord
  • development of a complex nerve system
  • replaces fxn of notochord
  • provides increased rigidity
  • provides attatchment for muscles and other skeletal elements
  • became more efficient at capturing food and avoiding being eaten
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10
Q

what are vertebrate synapomorphies?

A
  1. vertebrae enclosing nerve cord
  2. elaborate skull
  3. fin rays, in the aquatic forms
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11
Q

what are lampreys?

A

basal craniate, agnathan, class petromyzontida

  • oldest living vertebrate
  • cartilage skeleton
  • notochord surrounded by a cartilaginous tube - paired dorsal spines from tube partially enclosed nerve cord
  • primitive vertebral column
  • eyes with lenses, no jaws or paired limbs
  • look and behave like lancets (cephalochordates)
  • suspension feeders
  • ectoparasites of fish: clamp by funnel sucking mouth
  • use sucker for upstream travels
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12
Q

what are the origins of bone and teeth?

A

mineralization with calcium originated with vertebrate mouthpats

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13
Q

what are conodonts?

A
  • first vertebrates with mineralized skeletal elements in their mouth and pharynx
  • fossilized dental elements are common in fossil record
  • vertebrate endoskeleton became fully mineralized much later
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14
Q

what are gnathostome vertebrates?

A

vertebrates that have jaws

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15
Q

what are derived characteristics of vertebrates?

A
  • opposing jaws
  • mineralization of skeleton
  • 2 pairs of appendages (extinct agnathans - 1 pair, extant agnathans - no paired fins)
  • genome duplication, including duplication of hox genes (4 clusters)
  • enlarged forebrain – enhanced smell and vision
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16
Q

what are derived characteristics of vertebrates?

A
  • opposing jaws
  • mineralization of skeleton
  • 2 pairs of appendages (extinct agnathans - 1 pair, extant agnathans - no paired fins)
  • genome duplication, including duplication of hox genes (4 clusters)
  • enlarged forebrain – enhanced smell and vision
17
Q

where did jaws come from?

A

skeletal supports of pharyngeal slits

  • modification of 2 pairs of skeletal rods that had supported anterior pharyngeal slits - modified to pump water over the gills by opening and closing the mouth more effectively
  • the mouth could then grow bigger and wider – capture more prey
  • posterior slits became specialized for gas exchange
18
Q

what were the earliest fossil gnathostomes?

A

armoured vertebrates called placoderms

19
Q

what are the three lineages of jawed vertebrates alive today?

A
  • chondrichthyans
  • ray finned fishes
  • lobe fins
20
Q

what is class chondrichthyes?

A

sharks, rays, etc

  • cartilaginous fishes - cartilage endoskeleton; not a primitive character state – derived from ancestors with bony skeletons
  • have bony teeth
  • development of most vertebrates: skeleton is first cartilaginous and then becomes ossified; mineralization of cartilage by CaPO3 – chondrichthyans skip this
21
Q

what are sharks?

A
  • streamlined bodes and swift swimmers - propulsion from tial, pectoral fins for lift
  • NO SWIM BLADDER - buoyancy from storing oil in liver - sink while swimming, must use muscles to gulp water to aerate gill
  • short digestive tract with ridge called spiral valve to increase digestive surface area
  • CLOACA
  • rough skin - dermal placoid scales with spines, reduce drag, quieter
  • scales homologous with teeth
  • continuously shed and replace teeth
  • acute sense of sight and smell
  • detect electrical field
  • detect vibrations in water via lateral line
22
Q

what is shark reproduction?

A
  • copulation
  • males have pelvic fins modified as claspers, hold female and help to guide sperm
  • fertilized internally but embryos can develop in different ways
23
Q

what is oviparous?

A

eggs hatch outside mother’s body

24
Q

what is ovoviviparous?

A

embryo develops within uterus and nourished by egg yolk

25
Q

what is viviparous?

A

embryo develops within uterus and nourished through a yolk sac

26
Q

what is class chondrichthyes?

A

sharks, rays, etc

  • cartilaginous fishes - cartilage endoskeleton; not a primitive character state – derived from ancestors with bony skeletons
  • have bony teeth
  • development of most vertebrates: skeleton is first cartilaginous and then becomes ossified; mineralization of cartilage by CaPO3 – chondrichthyans skip this
27
Q

what are sharks?

A

chondrichthyes

  • streamlined bodes and swift swimmers - propulsion from tial, pectoral fins for lift
  • NO SWIM BLADDER - buoyancy from storing oil in liver - sink while swimming, must use muscles to gulp water to aerate gill
  • short digestive tract with ridge called spiral valve to increase digestive surface area
  • CLOACA
  • rough skin - dermal placoid scales with spines, reduce drag, quieter
  • scales homologous with teeth
  • continuously shed and replace teeth
  • acute sense of sight and smell
  • detect electrical field
  • detect vibrations in water via lateral line
28
Q

what is shark reproduction?

A
  • copulation
  • males have pelvic fins modified as claspers, hold female and help to guide sperm
  • fertilized internally but embryos can develop in different ways
  • protected in a leathery egg case
29
Q

what is viviparous?

A

embryo develops within uterus and nourished through a yolk sac placenta from mother’s blood

30
Q

what are rays and skates?

A

chondrichthyes

similar to sharks

  • swim by flapping pectoral fins
  • dorso-ventrally flattened
  • flat platelike teeth for grinding prey

Biology 108 (27 decks)

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