Fishes Flashcards

1
Q

What are the 6 Gnathostome synapomorphies?

A

jaws (derived from gill arches), most have dentin-based teeth, complex endoskeleton, 3 semi-circular canals, paired fins/limbs, gill tissue external to gill arches

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2
Q

What did Gnathostome jaws evolve from?

A

2 pharyngeal (branchial) arches - first arch becomes mandibular arch, 2nd arch becomes hyoid arch

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3
Q

What are placoderms?

A

extinct group of jawed fishes (430-359 Ma)

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4
Q

Where is placoderm armor located?

A

cranial and thoracic bony armor

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5
Q

T/F: Placoderms have teeth

A

False: jaws lined with self-sharpening occluding bony plates (no teeth)

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6
Q

What is donkleosteus?

A

predatory placoderm found in North America, Poland, Belgium, Morocco
- massive: 10m long, 4 tonnes

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7
Q

what is materpiscis (mother fish)

A

oldest known vertebrate to show matrotrophic viviparity (nutrition from mother and birth to live young). bears unborn embryo and mineralized umbilical cord

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8
Q

what are Acanthodians?

A

extinct group of paleozoic jawed fishes (450-290 Ma)

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9
Q

What are some features of acanthodians(spiny sharks)?

A

prominent spines at leading edges of fins, body covered in small non-overlapping rhomboid scales, single or multiple gill covers (operculum), large eyes

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10
Q

what are chondrichthyans?

A

cartilagenous fishes, fossil record extends back to paleozoic

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11
Q

what kind of jaw suspension do sharks have?

A

hyostylic jaw suspension; upper jaw has a weak ligamentous attachment to braincase and is mostly supported by the hyoid arch

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12
Q

what is the benefit of hyostylic jaw suspension

A

produces greater mobility of jaws and development of a protractile bite (increases ability to tear off large pieces of flesh or provide effective suction)

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13
Q

what are some features of sharks (chondrichthyans)?

A

active predators, cartilagenous endoskeleton, dermal skeleton composed of placoid scales (protection and reduce friction), fins composed of keratinized ceratotrichia

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14
Q

T/F: all extinct and extant male sharks have claspers

A

true

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15
Q

what function does the rectal gland serve?

A

osmoregulation: removes excess salt

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16
Q

what function does the liver serve in sharks?

A

replaces swim bladder, produces and stores squalene that reduces body density.
lighter than water - specific gravity of 0.85

17
Q

what is dynamic lift?

A

heteroceral tail pushes water posteriorly and ventrally producing a reaction forces with dorsal lift and anterior thrust components
flat ventral body and pectoral fins also produce lift

18
Q

what kind of jaw suspension do Batoids (rays) have?

A

euhyostylic jaw suspension (suspended solely by the hyoid arch)

19
Q

what are some features of batoids?

A

dorsoventrally flattened
expanded pectoral fins fused to head
eyes and enlarged spiracle are placed dorsally, mouth and gill slits placed ventrally

20
Q

what kind of jaw suspension do holocephalans have?

A

hyostylic (palatoquadrate fused to chondrocranium and not supported by hyomandibular)

21
Q

What are some features of holocephalans?

A

cartilaginous endoskeleton (males have claspers)
tooth plates
operculum covering gill arches
narrow whip-like tail
swim via rowing action of pectoral fins

22
Q

what are actinopterygians?

A

ray-finned fishes: fins fully “rayed” from base with bony lepidotrichia
fossil record dates back to Paleozoic

23
Q

what are chondrosteans?

A

primitive actinopterygians
used to be large group now only paddlefish and sturgeons

24
Q

what are some features of chondrosteans?

A

mostly cartilaginous endoskeleton, ganoid scales, unconstricted notochord, heteroceral tail, vascularized physostomous swim bladder

25
Q

what are holosteans?

A

intermediate actinopterygians
dated back to late permian

26
Q

what are some features of holosteans

A

heavily armored with ganoid scales, elongated body with heteroceral tail, posterior dorsal and anal fins, physostomous swim bladders, moderate ossification of endoskeleton

27
Q

what are teleosts?

A

derived actinoperygians
95% of all living fishes (more species than all other vertebrate classes combined)
first appeared in mid triassic - explosive radiation during jurassic

28
Q

what is the feeding mechanism for teleosts?

A

highly mobile upper jaw
rapid mouth opening creates negative pressure in the oral cavity drawing food items into mouth

29
Q

what function does the heteroceral tail serve?

A

provides dynamic lift for heavy primitive actinopterygians

30
Q

how is vertical movement accomplished by primitive actinopterygians?

A

primarily by pectoral fins

31
Q

what function does the teleost homoceral tail serve?

A

pushes water posteriorly producing a reaction force with anterior thrust component only

32
Q

what are some advantages of the homoceral tail?

A

increased efficiency in horizontal swimming (thrust is purely horizontal)
increased versatility (pectoral fins can take on other locomotory functions other than planing)

33
Q

what are sarcopterygians?

A

lobe-finned fishes
fossil record extends back to the Paleozoic
only 8 extant species

34
Q

what are some features of sarcopterygians?

A

lobed fins resembling ancestral tertrapods
fin muscles external to the body wall
cosmoid scales, choanae, hinge like joint on top of skull, prominent notochord, diphyceral tail

35
Q

what is the structure of cosmoid sclaes?

A

complex dentin-layer (cosmine) and an outer coating of enamel

36
Q

what are choanae?

A

paired internal openings into the oropharyngeal cavity

37
Q

what is Tiktaalik roseae?

A

transitional fishapod (intermediate between fish and amphibians
late devonian (375 Ma)

38
Q

what are some features of tiktaalik roseae?

A

cosmoid scales, tetrapod-like limb bones and functional wrist joint, heavy endoskeleton with robust ribs, well-developed pectoral girdle separate from skull, hinge-like intracranial joint