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Vertebrate Zoology > Chapter 3 -Early Vertebrates > Flashcards

Chapter 3 -Early Vertebrates Flashcards

1
Q

(Myxinoidea - Hagfish) - External Features

A
  • Elongated, scaleless, and pink or purple in color
  • Large mucus glands that open through the body wall to the outside (to deter predators)
  • Single terminal nasal opening that connects to the pharynx
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2
Q

(Myxinoidea - Hagfish) - Skeletal

A
  • Have a cranium, but lack vertebrae
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3
Q

(Myxinoidea - Hagfish) - Sensory

A
  • Only one semicircular canal on each side of the head

- Rudimentary eyes with thick skin

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4
Q

(Myxinoidea - Hagfish) - Feeding and Digestion - Morphology

A
  • Mouth is surround by six tentacles (barbels) (how you can tell the difference between Hagfish and Lamprey)
  • Two horny plates in the mouth that have sharp tooth like structures
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5
Q

(Myxinoidea - Hagfish) - Feeding and Digestion - Behavior

A
  • Primarily scavengers
  • Feed in large numbers
  • They can tie a knot in their tail to situate prey for feeding
  • A mucoid sac envelopes the food, enzymes digest it, and waste gets secreted within the sac
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6
Q

(Myxinoidea - Hagfish) - Excretory

A
  • Body fluids are the same as the environment (iso-osmotic)

- Primitive kidney with no collecting ducts

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7
Q

(Myxinoidea - Hagfish) - Respiratory

A
  • 1-15 external gill openings

- External gill opening is posterior, almost mid-body (enables them to breathe while burrowed head first in the sand)

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8
Q

(Myxinoidea - Hagfish) - Cardiovascular

A
  • Large blood sinus
  • Low blood pressure
  • True heart with 3 chambers
  • Accessory hearts (help pump blood) in the liver and tail (one of the only vertebrates that still have accessory hearts)
  • Aneural hearts - the pumping rhythm of the heart is intrinsic instead of being controlled by the CNS
  • Red blood cells that contain hemoglobin
  • Note: True heart and red blood cells containing hemoglobin are features that are derived characteristics for Craniata (everything from Hagfish on, have these features)
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9
Q

(Myxinoidea - Hagfish) - Reproduction

A
  • Sex ratio 100:1 females to males
  • Some species are hermaphoditic
  • Eggs are oval (~1cm long) and encased in a tough, clear covering that is secured to the bottom of the ocean floor by hooks
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10
Q

(Myxinoidea - Hagfish) - Development

A
  • No larval stage (direct development)

- Embryos do possess the neural crest

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11
Q

(Myxinoidea - Hagfish) - Ecology

A
  • Distirbution: Nearly worldwide, except polar regions
  • Habitat: Deep oceanic water inhabitants that burrow into the sand
  • Some species live in colonies and tend to live and breed locally
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12
Q

(Extinct, Jawless, Soft Bodied Fish - Myllokumingia and Haikouichthys)

A
  • Characters of both
  • Fossils found from the Early Cambirum in China
  • Small (~3cm), fish-shaped
  • Cranium
  • W-shaped myomeres (vertebrate feature)
  • Dorsal fin and ribbon like ventral fin
  • Paired sensory structures in the head
  • Segmental structures flanking the notochord
  • Characters of just Haikouichthys
  • Lamprey-like cartilaginous gill supports
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13
Q

(Petromyzontoidea: Lampreys) - External Features)

A
  • Similar in size and shape to Hagfish

- Single nasal opening

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14
Q

(Petromyzontoidea: Lampreys) - Skeletal - Arcualia

A

Primitive cartilaginous elements that are the precursor to true vertebrates

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15
Q

(Petromyzontoidea: Lampreys) - Sensory

A
  • Two semicircular canals

- Eyes are large and well-developed

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16
Q

(Petromyzontoidea: Lampreys) - Feeding and Digestion - Morphology

A
  • Round mouth
  • Oral hood- fleshy funnel, which is studded with horny conical spines
  • Protrusible tongue-like structure
  • Oral gland secretes an anticoagulant
  • Digestive tract is straight and simple
17
Q

(Petromyzontoidea: Lampreys) - Feeding and Digestion - Behavior

A
  • Parasitic on other fish

- Some species have non-feeding adults

18
Q

(Petromyzontoidea: Lampreys) - Excretory

A
  • Chloride cells in the glands and well-developed kidney regulate ions, water, and waste
19
Q

(Petromyzontoidea: Lampreys) - Respiratory

A
  • Seven pairs of gill pouches open just posterior to the head k
  • Tidal ventilation - water is both drawn in and expelled out through the gill slits (most fish use a flow-through ventilation (through mouth - out gills))
  • Velum - a flap that prevents the water from flowing out of the respiratory tube into the mouth
20
Q

(Petromyzontoidea: Lampreys) - Cardiovascular

A
  • Accessory hearts are lost
21
Q

(Petromyzontoidea: Lampreys) - Reproduction - Anadromous

A

Live as adults in oceans or big lakes and ascend rivers and streams to reproduce

22
Q

(Petromyzontoidea: Lampreys) - Reproduction - Semelparous

A

Reproduces a single time before it dies

23
Q

(Petromyzontoidea: Lampreys) - Reproduction - Nesting

A

Males and females make a nest together

24
Q

(Petromyzontoidea: Lampreys) - Reproduction - Eggs

A

Females produce hundreds to thousands of eggs, which are ~1mm in diameter and lack a protective covering

25
Q

(Petromyzontoidea: Lampreys) - Development

A
  • All have larvae (ammocoetes) that hatch in about two weeks
  • 7-10 days after hatching, ammocoetes (6-10mm long) leave the nest and currents carry them downstream to quiet banks of the river or stream
  • Larvae spends 3-7 (17?) years burrowed into sand as a filter feeder
  • Once the larvae reach 10 cm in length, it begins metamorphosis into a parasitic juvenile
  • Migration back to adult habitat doesn’t occur until the spring following metamorphosis
  • Adult stage last for 1-2 years
26
Q

(Petromyzontoidea: Lampreys) - Ecology

A
  • Distribution: Cooler waters in the northern and southern hemisphere
  • Habitat: Adults in oceans and big lakes. Larval stage in streams and rivers.
27
Q

(Petromyzontoidea: Lampreys) - Human Interaction

A
  • Petromyzon marinus, the sea lamprey, was indigenous to Lake Ontario, but became an invasive species to other great lakes through the Welland canal
28
Q

(Extinct Jawless Fish: Conodontia) - Vertebrate Characters

A
  • Myomeres
  • Notochord
  • Cranium
  • Large eyes
29
Q

(Extinct Jawless Fish: Conodontia) - Unique Characters

A
  • Conodont elements - small spine-like structures composed of apatite that are similar in their microstructure of dentine and thought to be tooth-like structure
30
Q

(Extinct Jawless Fish: Conodontia) - Derived Characters

A
  • Covering of dermal bone
  • Cerebellum in the hindbrain
  • Olfactory tract connecting the olfactory bulb to the forebrain
  • Lack jaw, but some had movable mouth plates
  • Most have midline dorsal fin (HUGE DEVELOPMENT)
31
Q

Basic Gnathostome Design Characteristics

A
  • Jaws formed from the mandibular gill arch.
  • Gill skeleton consists of jointed branchial arches and internal gill rakers
  • Hypobranchial musculature
  • Two distinct olfactory tracts leading to two distinct nostrils
  • Three semicircular canals in the inner ear
  • Conus arteriosus in the heart
  • Horizontal septum divides the epaxial and hypaxial portions of the muscles
  • Vertebrae now have a centra and ribs
  • Most have a well-developed heterocercal caudal fin
32
Q

What new behaviors did jaw allow?

A
  • New feeding behaviors
  • Allows for digging holes
  • Create nests with pebbles and vegetation
  • Grasp mates during courtship or juveniles during parental care
33
Q

Extinct Jawed Fish: Placoderms

A
  • Bony Shield
    • Covered 1/2-1/3 of anterior portion of their bodies
    • Head and trunk portions were separated by a mobile joint
  • Primarily marine, but also lived in freshwater and estuaries (area between freshwater and saltwater)
  • Myomeres are weakly W shaped and are not separated by a horizontal septum
  • 7 intrinsic eye muscles (most gnathostomes have 6)
  • Nerve lack myelin sheaths
  • Semidentine - type of cellular hard tissue in their dermal bodies
  • Internal fertilization
  • Primarily bottom dwellers
34
Q

Extinct Jawed Fish: Acanthodians

A
  • Stout spines anterior to their well-developed dorsal, anal, and paired fins
  • Up to six pairs of ventrolateral fins
  • Early forms were marine, but the clade is mostly freshwater
  • Slender bodies with a basic fusiform shape and hetercercal caudal fin
  • Habitat was midwater (not bottom dwellers)
  • Shark-like teeth

Vertebrate Zoology (5 decks)

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