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biol 361 marine bio > Nekton- Vertebrates > Flashcards

Nekton- Vertebrates Flashcards

1
Q

nekton can ___ themselves (swim __ the water)

A

propel
against

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2
Q

____ are jawless fishes like lampreys and hagfish

A

Agnatha

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3
Q

Chondrichthyes= ____ fishes including ____ and rays
They have:
- _____ skeleton
- replaceable ___ ___
- ___ skeleton

A

cartilaginous
sharks

cartilaginous
tooth rows (lose their teeth)
dermal

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4
Q

_____ are bony fishes with teeth fixed in jaws (much more diverse than Chondrichthyes)

A

Osteichthyes

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5
Q

Why aren’t we sure about the phylogenetic tree of hagfishes/ lampreys?

A

really hard to find eggs/ young/ DNA of hagfish
- hagfish could be an outgroup, or might be sister taxa to lampreys

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6
Q

hagfish have an eel-like body, and ___ but no ___

A

teeth but no jaws

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7
Q

what are 3 distinguishing characteristics of hagfish?

A
  • scavengers: they eat dead animals etc in deep waters- they burrow into the animal and eat it inside-out
  • rough skin, can absorb nutrients through the skin (absorb from the dead animals they’re inside of)
  • secrete immense amounts of slime for defense (hydrated collagen material, clogs gills of predators to deter them)
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8
Q

There are ~____ fish species in all habitats

A

30, 000

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9
Q

The form of fishes is related to their ___ and ____ ecology
What are the 5 forms? Give examples

A

locomotion and feeding ecology

  1. Rover- predators like tuna
  2. surface oriented- eat plankton (eg flying fish)
  3. Bottom fish- ie flat fish: eat small fish/ snails & create burrows
  4. Deep bodied- herbivores/ coral specialists eg butterfly fissh
  5. Eel-like
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10
Q

-
-
give an example of each

A
  • acceleration eg barracuda (predator)
  • cruising eg tuna (predator)
  • maneuvering eg butterflyfish (herbivore)
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11
Q

most fish are ____, meaning they’re __-blooded
Some have evolved ___ to allow hunting in cooler waters (eg tuna)

A

poikilotherms
cold

endothermy (warm-blooded)

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12
Q

sharks are a ___-specialist, so they rely on their ___ to propel them and swim

A

cruise

tail

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13
Q

for most fish, swimming usually involves ____ of their entire body (thrust)

A

undulation

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14
Q

What’s a Mola mola ocean sunfish?

A

a massive fish (3 species) related to pufferfish
- slow-moving and deep diving- feed on jellyfish
- endangered b/c they’re easy to catch in our nets :(

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15
Q

How do sharks stay buoyant?

A
  1. they have cartilage as a skeleton, which is lightweight compared to mineral skeletons
  2. control buoyancy by fat storage in their liver

*sharks must keep moving to stay buoyant

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16
Q

Often, bony fish have bones and tissues that are more dense than seawater. How do they stay buoyant?

A

They use a swim bladder

gas is exchanged through a network of capillaries called the rete mirabile

exchange of gas in from the blood into the swim bladder across capillaries in the rete mirabile

17
Q

T/F
blood flow is in the same direction as water flow in nekton

A

false

blood flow in opposite direction of water flow
“countercurrent exchange”

18
Q

How do fish do oxygen exchange?

A

water flows over gill lamellae and oxygen diffuses into gills

19
Q

sharks are ____, meaning their blood osmolarity is ~___ compared to seawater

A

isotonic
the same

20
Q

do sharks need to drink water? Do they need to excrete solutes?

A

No because they’re isotonic

Usually don’t need to excrete solutes, but if they do, it’s via the rectal gland

21
Q

Bony fish are __, meaning their blood has ___(fewer/more) solutes than seawater

A

hypotonic

blood has fewer solutes than seawater

22
Q

Do bony fish need to drink water? Do they need to excrete solutes?

A

Yes, they need to drink water and then excrete the solutes

Solute excretion is over gills (via chloride cells)

23
Q

t/f
some sharks can live in freshwater

A

true

24
Q

Sharks can be Euryhaline or stenohaline. Explain what this means

A

Euryhaline= able to conserve urea & absorb salts, so these sharks can live in freshwater (found high in estuaries)

Stenohaline= unable to survive long-term in water fresher than 50/50
- known to enter estuaries, but they return to saltwater

25
Q

Describe the teeth that sharks have

A

predatory sharks have teeth produced by a tooth bed (they’re temporary)
- dentine, but no root
- drop 1 tooth/ week minimum (great fossil record)

Sharks also have teeth in skin (dermal scales) to provide lightweight protection

26
Q

Some sharks are filter-feeders, like the ___ shark and ___ shark. How do they eat?

A

Basking sharks and whale sharks

they use gill rakers (bars on gills with filaments that collect tiny particles)

they eat plankton like copepods, shrimp
Filter 2000-6000L/hr= they get huge!

27
Q

whale sharks are ovoviviparous, meaning:

Why are whale sharks endangered?

A

they give birth to live young hatched from eggs inside the female

endangered b/c they’re hunted for fins and have a very long generation time

28
Q

Different sharks have 3 different methods of reproduction:
1
2
3
give an example for each

A
  1. oviparous: lay egg cases that can wrap around any structure
    - eg many sharks and rays
  2. Viviparous: placental- give birth to live young
    - eg bull shark
  3. Ovoviviparous: produce eggs, which hatch inside the female –> give birth to live young
    - eg whale shark
29
Q

why don’t sharks have very sustainable populations?

A

they take a long time to reach reproductive age & don’t produce many young

30
Q

Sharks have good hearing; explain how it works

A

their ears are behind their eyes
- hair cells= very sensitive to low-frequency sounds and have good directional hearing

31
Q

How do sharks detect water vibrations?

A

Lateral Line system
- hair cells in fluid-filled canals down the head and trunk to detect water vibrations

32
Q

Sharks have ampullae of lorenzini. What are they?

A

small pores filled with glycoproteins that detect electrical fields

33
Q

Sharks have a good sense of smell through ___

A

nares

34
Q

sharks have color vision and see well in __-intensity light with two specialized features:

  1. 2.
A

low

  1. tapetum locidum
  2. nictating membrane
35
Q

What is the tapetum lucidum

A

a specialized feature of shark’s eyes to be able to see in low light
- a reflective surface behind the retina boots the visual signal in low light levels

36
Q

What is the nictating membrane?

A

a cover over the shark eye to protect it from damage when feeding (like an eyelid- they feed very aggressively)

37
Q

Which 3 categories fall into Nekton?

A

1 jawless fish (agnatha)
2. cartilaginous fish (sharks)
3. bony fish

38
Q

sharks are ___ swimmers- the caudal fin provides ___, and lift is provided by ___ fins

A

cruise

thrust
pectoral

biol 361 marine bio (18 decks)

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