Early Vertebrates PART I VERTEBRATE ZOOLOGY (VZ Lecture04 – Spring 2012 Althoff - reference PJH...

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Early Vertebrates PART I VERTEBRATE ZOOLOGY (VZ Lecture04 – Spring 2012 Althoff - reference PJH Chapter 3)

Transcript of Early Vertebrates PART I VERTEBRATE ZOOLOGY (VZ Lecture04 – Spring 2012 Althoff - reference PJH...

Page 1: Early Vertebrates PART I VERTEBRATE ZOOLOGY (VZ Lecture04 – Spring 2012 Althoff - reference PJH Chapter 3)

Early VertebratesPART I

VERTEBRATE ZOOLOGY (VZ Lecture04 – Spring 2012 Althoff - reference PJH Chapter 3)

Page 2: Early Vertebrates PART I VERTEBRATE ZOOLOGY (VZ Lecture04 – Spring 2012 Althoff - reference PJH Chapter 3)

PALEOZOIC (late Carboniferous Period)

Terrestrialnonamniotetetrapods

open water

shallow lake

lakemargin

upland

earlyamniote

12

3 4

5

Fig. 7-5 p165 PJH

Page 3: Early Vertebrates PART I VERTEBRATE ZOOLOGY (VZ Lecture04 – Spring 2012 Althoff - reference PJH Chapter 3)

The most conspicuous new features of early vertebrates vs. nonvertebrate chordates:

A ______________ end that….A) contained a tripartite brain that

was B) enclosed by a cartilaginous cranium C) containing sense organs

Newly acquired pharyngeal musculatureto draw water into the mouth and

over the gills _________________ …not for filter feeding (i.e, acquiring food).

Page 4: Early Vertebrates PART I VERTEBRATE ZOOLOGY (VZ Lecture04 – Spring 2012 Althoff - reference PJH Chapter 3)

Early vertebrates

• Fossil deposits, ~540 MYAA) Myllokumingia (see next slide), China B) Haikouichthys China, too—same deposits

• Small, fish-shaped, ~ 3 cm long

• _____________ present

• _____________ present

• BUT _____ evidence of bone or mineralized scales

• Dorsal fin and ribbonlike pairs of ventrolateralfins

Page 5: Early Vertebrates PART I VERTEBRATE ZOOLOGY (VZ Lecture04 – Spring 2012 Althoff - reference PJH Chapter 3)

Fig. 3-1 p44 PJH

Myllokumingia

Astrapis

MYOMERES

DORSAL FIN

VENTROLATERAL FIN

Page 6: Early Vertebrates PART I VERTEBRATE ZOOLOGY (VZ Lecture04 – Spring 2012 Althoff - reference PJH Chapter 3)

Next….bone fragments in fossil

• Fossil deposits: Australia, Bolivia, North America A) Astraspis (North America “version”)

• Large, fish-shaped, ~ 12 - 35 cm long

• Armored – close-fitting, polygonal bony plates

• Eye “protection”

• Torpedo-shaped

• Jawless

Page 7: Early Vertebrates PART I VERTEBRATE ZOOLOGY (VZ Lecture04 – Spring 2012 Althoff - reference PJH Chapter 3)

Fig. 3-1 p44 PJH

Myllokumingia

Astrapis

BONY PLATES/SCALES

EYEPROTECTION

Page 8: Early Vertebrates PART I VERTEBRATE ZOOLOGY (VZ Lecture04 – Spring 2012 Althoff - reference PJH Chapter 3)

Conodonts – “microfossils”

• _____________ elements of true vertebrates

• < 1mm long

• Composed of apartite = __________________ compound characteristic of vertebrate tissue

• Much like _____________ (making it uniquely vertebrate tissue)

• Complete impressions of conodont animals with the “conodont” elements arranged within the pharynx thus confirming they were true vertebrates

Page 9: Early Vertebrates PART I VERTEBRATE ZOOLOGY (VZ Lecture04 – Spring 2012 Althoff - reference PJH Chapter 3)

Fig. 3-2 p45 PJH

Clydagnathus

Idiognathus

CONODONTS

________ elements(anterior)

_________Elements(posterior)

Page 11: Early Vertebrates PART I VERTEBRATE ZOOLOGY (VZ Lecture04 – Spring 2012 Althoff - reference PJH Chapter 3)

Fig. 3-3 p46 PJH

Page 12: Early Vertebrates PART I VERTEBRATE ZOOLOGY (VZ Lecture04 – Spring 2012 Althoff - reference PJH Chapter 3)

Origin of Bone & Mineralized Tissue

• Origin of mineralized tissues still somewhat uncertain

• Earliest known types are _______________ in structure than mineralized tissues of living vertebrates

• ____________ basic units of mineralized tissue…tooth-like elements formed “____” the skin (in dermal layer…unlike mollusks), then overlaid by epidermis

• No cells in adult form….acellular

Page 13: Early Vertebrates PART I VERTEBRATE ZOOLOGY (VZ Lecture04 – Spring 2012 Althoff - reference PJH Chapter 3)

__________________ of Mineralized Tissue?

• Defensive structures against predator attacks

• Design of bony tissue resulted in more complex function that merely protection:system of pores and small projections suggest ____________________

• Protective against predators & insulating coating around ______________________ that increased detection of prey

or

• Subsequent advantage: ______________ & _______________ deposition and subsequent mobilization

Page 14: Early Vertebrates PART I VERTEBRATE ZOOLOGY (VZ Lecture04 – Spring 2012 Althoff - reference PJH Chapter 3)

Which happened first?

• Vertebrates evolved first in freshwater or first in marine ecosystems?

--some early thinking was that because ofvertebrate kidney clearly being anadvantage in freshwater, that mostearly evolution took place there

--now, thinking is that _________ was “fortuitously preadapted” for fresh-water exist….that withstanding, “early” evolution likely was in

_______ ecosystems.

Page 15: Early Vertebrates PART I VERTEBRATE ZOOLOGY (VZ Lecture04 – Spring 2012 Althoff - reference PJH Chapter 3)

Evidence of marine origin

• Earliest vertebrate __________ found in marine sediments (paleontological evidence)

• All nonvertebrate chordates and deuterostome invertebrates (starfish, sea urchins,

etc.) are exclusive marine forms (comparative physiological evidence) where ____________ in same concentrations as seawater

Page 16: Early Vertebrates PART I VERTEBRATE ZOOLOGY (VZ Lecture04 – Spring 2012 Althoff - reference PJH Chapter 3)

Extant (“still living”) Jawless Fishes

• Two representatives: _________ & __________

• No specialized reproductive ducts…eggs and sperm released into coelum

• Primitive handling of drainage from kidneys (no duct-work, more through pores)

• External fertilization of eggs

• Considered ________________ a subset of “Agnathans” = jawless fishes preceeding conodonts and ostracoderms—both of which are extinct groups.

Page 17: Early Vertebrates PART I VERTEBRATE ZOOLOGY (VZ Lecture04 – Spring 2012 Althoff - reference PJH Chapter 3)

Fig. 3-4 p48 PJH

Page 18: Early Vertebrates PART I VERTEBRATE ZOOLOGY (VZ Lecture04 – Spring 2012 Althoff - reference PJH Chapter 3)

Hagfishes

• Family: Myxinoidea

• Two major genera: Eptatretus and Myxine

• ~ 40 species

• ~ 0.5 m in length, elongated

• ________ scales

• ________ vertebrae

• Simple kidneys

• Eyes degenerate, covered with thick skin

• Tooth-like plates

• Found nearly worldwide (except polar regions)

• Primarily deep-sea, cold-water inhabitants

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Page 20: Early Vertebrates PART I VERTEBRATE ZOOLOGY (VZ Lecture04 – Spring 2012 Althoff - reference PJH Chapter 3)

Hagfishes

• _________________ ….slime glands produce gelatinous mess that is a deterrent to predators. After threat gone, makes a knot to scrap off mass of mucus, then sneezes sharply to blow nasal passage clear.

• ______________ find food by sense of ______

• Also, use the “tying the knot” routine to brace themselves against their prey, mouth attaches to part of prey to tear off the flesh with pinching grasp….enough to expose soft coelomic cavity of prey.

• Digestion accomplished in a mucoid bag secreted by gut…nutrients diffuse out, then absorbed

Page 21: Early Vertebrates PART I VERTEBRATE ZOOLOGY (VZ Lecture04 – Spring 2012 Althoff - reference PJH Chapter 3)

Fig. 3-5 p49 PJH

Page 22: Early Vertebrates PART I VERTEBRATE ZOOLOGY (VZ Lecture04 – Spring 2012 Althoff - reference PJH Chapter 3)

Lampreys

• Family: Petromyzontoidea

• Two major genera: Petromyzon and Lampetra

• ~ 40 species

• ______ scales, up to 1 m in length

• ___ vertebrae, but “vertebral structures” (arculalia)that are ________________ skeletal

elements

• Kidneys – much _____________ over hagfishes, enables better regulation of ions,

water, and nitrogeneous waste…

• Exist in ___________ of salinities

• Found mostly in northern latitudes - temperate

• Most are _________________ live in sea/lake, breed in rivers or streams

Page 23: Early Vertebrates PART I VERTEBRATE ZOOLOGY (VZ Lecture04 – Spring 2012 Althoff - reference PJH Chapter 3)

Lampreys

• __________ on other fishes (usually bony fishes, but sometimes mammals = whales & porpoises)

• Attach to host by suction

• Oral gland secretes anticoagulant that prevents host’s blood from clotting

• Thus, bulk of lamprey’s diet is ___________ of the hosts

• _______, straight digestive tract…_______ “food”, _______ “digestion”

• Like many parasites, they don’t end up killing the host…only weaken them

Page 24: Early Vertebrates PART I VERTEBRATE ZOOLOGY (VZ Lecture04 – Spring 2012 Althoff - reference PJH Chapter 3)

Also see….Fig. 4-5 p30 FS

LAMPREYoral region

Tooth-like organs

(origin: ectoderm)

Page 25: Early Vertebrates PART I VERTEBRATE ZOOLOGY (VZ Lecture04 – Spring 2012 Althoff - reference PJH Chapter 3)

Lampreys

• Females produce hundreds to thousands of eggs, spawn with males after constructing a nest. Fertilized eggs get “surrounded” by larger rocks that create an eddy, dropping sediment over the eggs

• Adults die after breeding once

• Larvae hatch in about 2 weeks….known as Ammocoets, they float downstream, burrow in mud or sand and spend about the next ____ years as ______________________.

• Finally, metamorphosis into juvenile and become parasitic

Page 26: Early Vertebrates PART I VERTEBRATE ZOOLOGY (VZ Lecture04 – Spring 2012 Althoff - reference PJH Chapter 3)

Lampreys: Conservation Concern

• May have been indigenous to Lake Ontario….but not in any other Great Lakes until _________

• Devasting to sport and commercial fish populations in the Great Lakes—especially Lake Erie by the 1940s.

• Huge efforts in past 50-60 years to curb their numbers:

chemical lampricideselectrical barriers

mechanical weirs

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Page 28: Early Vertebrates PART I VERTEBRATE ZOOLOGY (VZ Lecture04 – Spring 2012 Althoff - reference PJH Chapter 3)

Lake trout

Sea lamprey