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Marine Bio > Nekton > Flashcards

Nekton Flashcards

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1
Q

What are Nekton

A

Organisms that can swim against an ocean current

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2
Q

General characteristics of Nekton

A

Larger body size
Greater swimming power
Most nektons are vertebrates
Most vertebrates are fish
Only the squid and a few species of shrimps are truly nektonic invertebrates
Include seabirds, reptiles, mammals but not amphibians

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3
Q

Importance of Nekton

A

Large nekton can influence marine communities
Important in current or historical harvests
Fishes of critical importance to world food supply

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4
Q

Vertical distribution

A
  • Epipelagic countershading
    – Countershading:
    a nektonic organism is bicolored, dark above and light below
  • Holoepipelagic:
    shark, tuna, ocean sunfish
  • Meroepipelagic:
    herring, salmon
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5
Q

Morphological features of nekton at Mesopelagic zone

A

– Seldom exceed 10 cm
– Equipped with well developed teeth and large mouth
– Large light-sensitive eyes, uniformly black
– Photophores: light-producing organs

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6
Q

Morphological features of nekton at Abyssalpelagic zone

A

– Species-specific pattern of photophores
– Small with flabby, soft, nearly transparent flesh
supported by weak bones
– Oversized mouth

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7
Q

Nekton and reynolds numbers

A
  • Ratio of inertial forces to viscous forces:
    – Re=LV/ɷ
    L=length
    V=velocity
    ɷ = viscosity
  • Water viscosity consistent, therefore Reynolds numbers change as a function of size and of velocity
  • Small objects viscosity most important
  • Large objectives inertia most important
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8
Q

Cephalopods - what are the two extant xub-classes

A
  • Nautiloidea
  • Coleoidea
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9
Q

Fishes: chondrichthyes, osteichthyes & Chondrichthyes

A

– Elasmobranchii (sharks, rays, skates, and sawfish)
– Holocephali (chimaeras)
* Osteichthyes
– Sarcopterygii (lobe-finned fishes)
* Coelacanths & lung fish
– Actinopterygii (ray-finned fishes)

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10
Q

Sea turtles

A

All sea turtles are nekton

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11
Q

Sea birds

A

All sea birds are nekton

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12
Q

Marine mammals - Sub order Pinnipeds

A

Family: Odobenidae
Family: Ottariidae
Family: Phocidae

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13
Q

Marine mammals - Order Cetaceans

A

Suborder: Mysticeti
Suborder: Odontoceti

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14
Q

Marine mammals - Order Sirenia

A

Family: Trichechidae
Family: Dugonidae

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15
Q

Nekton live in predictable environments, what are the factors

A

a)Iteroparous
b)Long-lived
c)Delayed maturity
d)Low-reproductive rates
e)Migratory

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16
Q

Iteroparity

A

Means living to reproduce repeatedly
* Sea Turtles
Return to natal beaches each year
* Cetaceans
Return to calving grounds annually
* Sharks
Site fidelity

17
Q

Semelparity:

A
  • Cephalopods
    After mating & egg deposition both sexes die
18
Q

Cold blooded

A
  • Most fish are cold-blooded – poikilothermic
  • Bodies same temperature as environment
  • Not fast swimmers
19
Q

Warm blooded

A
  • Some are warm-blooded – homeothermic
  • Found in warmer environments
  • Helps them capture prey
20
Q

Adaptations of Deep-Water Nekton

A
  • Mainly fish that consume detritus or each other
  • Lack of abundant food
  • Bioluminescence
    – photophores
  • Large, sensitive eyes
  • Large sharp teeth
  • Expandable bodies
  • Hinged jaws
  • Counterillumination
21
Q

Marine Reptiles

A
  • Ectothermic
  • Covered with scales
  • Breathe air with lungs
  • Have specialized salt glands to excrete excess salt taken in from seawater
22
Q

Marine Mammals

A
  • Land-dwelling ancestors
  • Warm-blooded
  • Breathe air
  • Hair/fur
  • Bear live young
  • Mammary glands for milk
23
Q

Major marine mammal groups:

A

Order Carnivora, Order Sirenia, Order Cetacea, Order Cetacea

24
Q

Order Carnivora

A
  • Prominent canine teeth
  • Sea otters
  • Polar bears
  • Pinnipeds
    – Walruses
    – Seals
    – Sea lions
    – Fur seals
25
Q

Seals vs. Sea Lions and Fur Seals

A
  • Seals lack prominent ear flaps
  • Seals have smaller front flippers
  • Seals have fore flipper claws
  • Different hip structures
  • Different locomotion strategies
26
Q

Order Sirenia

A
  • Herbivores
  • Manatees
    – Coastal areas of tropical Atlantic Ocean
  • Dugongs
    – Coastal areas of Indian and western Pacific Oceans
27
Q

Order Cetacea

A
  • Whales, dolphins, porpoises
  • Elongated skull
  • Blowholes on top of skull
  • Few hairs
  • Fluke – horizontal tail fin for propulsion
  • Adaptations to increase swimming speed
  • Adaptations for deep diving
  • Use oxygen efficiently
  • Muscles insensitive to buildup of carbon dioxide
  • Collapsible lungs
28
Q

Order Cetacea, Suborder Odontoceti (toothed):

A

– Dolphins, porpoises, killer whale, sperm whale
– Echolocation to determine distance and direction to objects
– Determine shape, size of objects

29
Q

Order Cetacea, Suborder Mysticeti

A
  • Baleen whales
  • Blue, fin, humpback, gray, right
  • Fibrous plates of baleen sieve prey items
  • Vocalized sounds for various purposes

Marine Bio (13 decks)

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