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marine bio > benthic invertebrates, nekton > Flashcards

benthic invertebrates, nekton Flashcards

some Cetacea, Pinnipeds & Sirenia

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1
Q

state roles of benthic invertebrates in ecosystem functioning

A
  • 2° production
  • nutrient recycling
  • habitat structure
  • grazing
  • predation
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2
Q

the taxonomic group ‘Phylum Cnidaria’

A

2 body forms:

  • medusae (jellyfish like)
  • polypoid (anemone like)

^have radial symmetry & are diploblastic

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3
Q

diploblastic animals

A

have body derived from only 2 embryonic cell layers:

  • ectoderm
  • endoderm

… but no mesoderm

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4
Q

state and describe cnidarians key feature

A

nematocysts

  • large organelles produced from Golgi apparatus
  • … as secretory product within a specialized cell (nematocyte / cnidocyte)
  • nematocysts: used for prey capture and defense and locomotion
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5
Q

cold water corals: Lophelia pertusa

A
  • these reefs provide habitat for variety of species and living and dead coral skeletons provide biodiversity hot spot on edge of continental shelf
  • lives between 80-3000m deep
  • found in west scotland and ireland
  • damaged by fishing and v delicate & grows slowly => long time for them to recover
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6
Q

sea pens: Anthozoa

A

each sea pen is a colony of polyps (cnidarians with polypoid shape)

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7
Q

marine invertebrates

A
  • porifera -> sponges
  • cnidaria -> jellyfish, anemones, corals
  • ctenopora -> comb jellies
  • polychaeta -> bristle worms (annelida)
  • mollusca -> polyplacophora, bivalves, gastropods
  • echinodermata -> starfish, brittle stars, sea urchins, sea cucumbers
  • crustacea -> decapods, seed shrimp, krill, isopods, barnacles, copepods
  • hemichordata -> balanoglossus, saccoglossus
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8
Q

hemichordata

A

2 body plans:

  • large, solitary acorn worms -> class Enteropneusta
  • filter-feeding colonies of the class Pterobranchia.
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9
Q

nutrient recycling

A
  • way in which elements are continuously being broken down and/or exchanged…
  • … for reuse between the living and non-living components of an ecosystem
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10
Q

grazing

A

method of feeding

where herbivore feeds on low-growing plants such as grasses or other multicellular organisms (eg. algae)

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11
Q

nekton

A

organisms that can move independently of currents

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12
Q

importance of nekton

A
  • nektonic fish of critical importance to world food supply
  • large nekton can profoundly influence marine communities
  • important in harvests (current and historical)
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13
Q

epipelagic countershading

A
  • most epipelagic organisms have ‘countershading’
  • they’re bicoloured: dark on top, silvery on bottom
  • allows organisms to blend into darker water below and lighted surface above when other organisms look down or up at it

eg. tuna

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14
Q

holoepipelagic organisms

A
  • spend entire lives in epipelagic zone
  • often lay eggs and have epipelagic larval life
  • eg. shark, tuna, ocean sunfish
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15
Q

meroepipelagic zones

A
  • spend part of lives in epipelagic zone
  • visit this region to find prey
  • spawn in inshore / freshwater regions
  • eg. herring, salmon
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16
Q

photophores

A
  • organs used by fish and invert. to produce light by chemical reaction / through bioluminescence
  • most fish that use photophores live in deep sea where light is limited
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17
Q

morphological features of nekton in mesopelagic zone

A
  • rarely exceeds 10cm long
  • good teeth and large mouth
  • large, light sensitive, black eyes
  • has photophores
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18
Q

morphological features of nekton in abyssopelagic zone

A
  • “species-specific pattern of photophores”
  • small flabby, soft, **nearly transparent flesh **supported by weak bones
  • oversized mouth
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19
Q

cephalopods

A
  • 2 sub-classes: Nautiloidea & Coleoidea
  • coleoidea…
    -> superorder: Decapodiformes (squid & cuttlefish)
    -> superorder: Octopodiformes (octopus & vampire squid)
  • semelparous -> breeding only once in a lifetime (squid, cuttlefishes & octopuses)
  • iteroparous -> multiple reproductive cycles over lifetime (nautiluses)
20
Q

chondrichthyes

fish

A

skeletons that are mainly made of cartilage

2 sub-classes:

  • elasmobranchii (sharks, rays, skates, and
    sawfish)
  • holocephali (chimaeras)
21
Q

osteichthyes

fish

A

“bony fish” -> skeletons mainly made of bone tissue

2 sub-classes:

  • sarcopterygii (lobe-finned fish)
    eg. coelacanths & lung fish
  • actinopterygii (ray-finned fish)
    eg. goldfish & ocean sunfish
22
Q

pinnipeds

A

seals

23
Q

cetaceans

A

includes whales, dolphins & porpoises

24
Q

cetaceans key characteristics

A
  • fully aquatic lifestyle
  • streamlined body shape
  • often large size
  • exclusively carnivorous diet
25
Q

sirenia and their characteristics

sirenia is an order

A

sea cows

  • fully aquatic, herbivorous mammals
  • inhabit swamps, rivers, estuaries, marine wetlands & coastal marine waters

2 distinct families:

  • Dugongidae -> 1 sp: dugong
    -> SE Asia, Australia & East Africa
  • Trichechidae -> inc all manatees
    -> 3 sp
    -> Amazon, West Indian &West African
26
Q

compare and contrast dugong and manatees

A

dugong:

  • short flippers
  • whale-like tail (fluke)
  • fusiform body

manatee:

  • long & flexible flippers
  • spatulate tail (fluke)
  • rough skin + algae
  • barrel shaped
27
Q

cold-blooded vs. warm-blooded fish

A

cold blooded = poikilothermic (most fish are):

  • bodies same temp as env
  • not fast swimmers

warm blooded = homeothermic:

  • found in warmer env
  • helps them capture prey
28
Q

adaptations of deep-water nekton

like in finding nemo

A
  • mainly fish that consume detritus / each other
  • lack of abundant food
  • bioluminescence – photophores
  • large, sensitive eyes
  • large sharp teeth
  • expandable bodies
  • hinged jaws
  • counterillumination
29
Q

counterillumination

A
  • active camouflage seen in marine animals eg. firefly squid & midshipman fish
  • producing light to match their backgrounds in both brightness & wavelength
30
Q

what are the predictable env for nekton

LIFE HISTORY - how they live

A
  • iteroparous -> producing offspring more than once during its lifetime
  • long-lived (longevity)
  • delayed maturity
  • low-reproductive rates
  • migratory
31
Q

life history

A

series of changes undergone by organism during its lifetime

32
Q

examples of nekton’s longevity

A
  • Osteichthyes:
    e.g. orange roughy -> ~150 yrs
  • Chondrichthyes:
    (oldest known vertebrate): greenland shark -> ~400 yrs
    -> based on radio-carbon dating eye lenses
33
Q

marine reptiles

A
  • ectothermic (cold-blooded)
  • covered with scales
  • breathe air with lungs
  • have specialised salt glands -> excrete excess salt taken in from seawater
34
Q

marine mammals

A
  • land-dwelling ancestors
  • warm-blooded
  • breathe air
  • hair/fur
  • have kids young
  • mammary glands for milk
35
Q

major marine mammal orders

A
  • Carnivora -> pinnipeds, sea otters, polar bears
  • Sirenia -> manatee, dugong
  • Cetacea -> whales
36
Q

order Carnivora

A
  • prominent canine teeth

what it includes:

  • sea otters
  • polar bears
  • pinnipeds
    – Walruses – Seals
    – Sea lions – Fur seals
37
Q

seals vs. sea lions & fur seals

A
  • seals lack prominent ear flaps
  • seals: smaller front flippers
  • seals: fore flipper claws
  • diff hip structures
  • diff locomotion strategies
38
Q

order Sirenia

A
  • herbivores

what it includes:

  • manatees
    – coastal areas of tropical Atlantic Ocean
  • dugongs
    – coastal areas of Indian and w. Pacific Oceans
39
Q

order Cetacea

A

Whales, dolphins, porpoises

  • elongated skull
  • blowholes on top of skull
  • few hairs
  • fluke – horizontal tail fin for propulsion
40
Q

Cetacea adaptations

A
  • adaptations to ↑ swimming speed
  • adaptations for deep diving
  • use oxygen efficiently
  • muscles insensitive to buildup of CO₂
  • collapsible lungs
41
Q

Suborder Odontoceti (toothed)
of order Cetacea

A
  • dolphins, porpoises, killer whale, sperm whale
  • echolocation to determine distance and direction to objects
    -> determine shape, size of objects
42
Q

dolphins vs porpoises

A

Dolphins:

  • larger, more streamlined shape
  • longer rostrum (beak)
  • falcate dorsal fin (hooked)
  • pointy teeth like killer whales (orca)

Porpoises:

  • smaller, more stout body shape
  • blunt snout
  • triangular, smaller dorsal fin
  • blunt or flat teeth
43
Q

echolocation

A
  • toothed whales send sound through water
  • sound is reflected, returned to animal, and interpreted
  • evolved inner ear structure may help toothed whales pick up sounds
  • ↑ marine noise pollution may affect cetacean echolocation
  • good vision of marine mammals limited by ocean conditions
  • mammals emit clicks of diff pitches
    -> low freq – great distance
    -> high freq – closer range
  • dolphins can detect schools of fish at more than 100m
44
Q

Suborder Mysticeti (moustached whales) of order Cetacea

A
  • baleen whales
  • blue, fin, humpback, gray, right whales
  • fibrous plates of baleen sieve prey items
  • vocalized sounds for various purposes
45
Q

gray whale migration

A
  • 22,000 km annual migration from coastal Arctic Ocean to Baja California & Mexico
  • feeding grounds in Arctic (summer) -> near Alaska
  • breeding & birthing grounds in tropical eastern Pacific (winter) -> near Mexico
46
Q

Nekton life-histories consequences

A
  • scale of movement requires global efforts “conserving a moving target”
  • over-exploitation and longevity:
    -> orange roughy collapsed stock
  • bycatch impacts e.g. albatross
47
Q

causes of nekton life-histories

A

FOOD

  • selection for large size – takes time to grow
  • resources patchy
  • travelling long distances is necessary
  • may take yrs to learn how to find food
  • selection will favour slow turnover rates

marine bio (11 decks)

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