Zooplankton

Question 1

Zooplankton

Answer 1

Planktonic Organisms. Protists or metazoans (multicellular, with cells differentiated into tissues, organs, digestive cavity)

Question 2

What do phytoplankton feed on

Answer 2

Phytoplankton, other zooplankton or detritus ; heterotrophic

Question 3

Microzooplankton

Answer 3

<200μm

Macrozooplankton >2mm

Question 4

Mesozooplankton

Answer 4

0.2-20mm

Question 5

Herbivores

Answer 5

Feed exclusively on phytoplankton

Detrivores: feed on detritus
Omnivores: feed on phytoplankton and zooplankton

Question 6

Carnivores

Answer 6

Feed primarily on other zooplankton

Question 7

Holoplankton

Answer 7

Planktonic throughout life cycle

Question 8

Meroplankton

Answer 8

Spend part of their life cycle as plankton before/after being nekton or benthos

Question 9

Holoplankton- Planktonic Foraminifera

Answer 9

• Prosita
• Heterotrophic
• Carbonate shell
• Live in epipelagic and mesopelagic zones
• All environments tropics to poles, species composition varies
• Many have symbionts

Question 10

Holoplankton- Radiolaria

Answer 10

• Protista, heterotrophic
• Omnivores
• Many have siliceous shells
  Live throughout the epipelagic and mesopelagic zones
• Highest abundance in warm equatorial waters
• Can live in deep ocean
• Many have symbionts

Question 11

Holoplankton- salps (sea grape)

Answer 11

• Planktonic tunicate
• Phylum: Chordata
• Sack-like filter feeders
• Phytoplankton grazers: very high consumption and growth rates
• Moves by pumping water through gelatinous body
• Asexual reproduction by division
• Highest concentrations in the Southern Ocean

Question 12

Holoplankton- Euphausiids- krill

Answer 12

• Generally omnivores:
• 86 known species
• Major component of the diet of larger fish (e.g. herring, salmon),whales, seals, seabirds
• Key consumer and prey item in Southern Ocean food webs

Question 13

Holoplankton- Crustaceans - Copepoda

Answer 13

• Most abundant zooplankton taxon (sub class), plays a major role in food chain and largest biomass in oceans
• Found at all depths
• 3 distinctive body parts, cephalosome, antennae, abdomen
• Omnivores- algae, diatoms, bacteria, zooplankton, copepod eggs

Question 14

Holoplankton- Crustacean- Ostracoda

Answer 14

• Ubiquitous throughout the world’s oceans: surface to abyssal depths
• Planktonic or benthic
• High abundance in the mesopelagic zone (2nd after copepods)
• Detritivores: feed on marine snow

Question 15

Holoplankton- Gastropoda- gelatinous snails

Answer 15

• Phylum: mollusca
• Metazoa
• May have shells or thin shell cups
• Foot (pseudopodia) evolved into a single fin or wings for swimming
• Heteropods and pteropods
• Carnivores: feed on other planktonic molluscs, copepods
• Average size: 0.5-5cm
• Found in all major ocean basins in upper ~10 m

Question 16

Holoplankton- Marine planktonic worms

Answer 16

• carnivorous- prey on planktonic animals
• Hermaphroditic - carry eggs and sperm

Question 17

Meroplankton to nekton

Answer 17

Spend part of their life cycle as plankton before/after being nekton or benthos e.g. octopus larvae, larval flounder, squid larvae

Question 18

Meroplankton from benthos - Jellyfish

Answer 18

• 2 life history phases: bottom-dwelling polyp, planktonic medusa
• Carnivores: prey on zooplankton,large fish
• Average size: 2mm – 2m
• Tentacles can measure >30m, some venomous
• Ubiquitous in epipelagic and mesopelagic zones, coastal zones to open ocean

Question 19

Epipelagic zooplankton: 0-200m

Answer 19

• Euphotic and upper dysphotic
  light zones
• May be permanent residents or may migrate vertically
• Herbivores, carnivores, omnivores
• Diverse marine life: protists, crustaceans, gastropods, worms, meroplanktonic larvae

Question 20

Epipelagic zoo plankton

Answer 20

0-200m= euphotic and upper dysphotic light zones

Question 21

Mesopeglagic zooplankton

Answer 21

Twilight (blue and green) to aphotic

Question 22

Temperature change through thermocline

Answer 22

Decreases to <5 C

Question 23

Pressure increases mesopelagic zone

Answer 23

1atm/10m

Question 24

Adaptations of mesopelagic zooplankton

Answer 24

Bioluminescence: light produced and emitted by organisms
Oxidation of organic compounds
Predator defence
Camouflage

Question 25

Morphological adaptations of mesopelagic zooplankton

Answer 25

Large eyes of marine gastropods give high sensitivity to green-blue wavelengths

Question 26

Adaptations of bathypelagic (1000-2000m) and abyssalpelagic (2000-6000m)

Answer 26

–>Carnivores and detrivores
–> Deep red/clack
–> Increased bioluminescence
–> Smaller eyes than mesopelagic species

Question 27

Midsummer zooplankton biomass

Answer 27

Maximum biomass in surface waters/ upper mesopelagic - reduction with depth

Question 28

Diel Vertical migration

Answer 28

=phenomenon where organisms in the ocean, such as zooplankton and some fish, move up to shallower depths during the night and return to deeper depths during the day. This behavior is often linked to feeding patterns and predator avoidance strategies

Question 29

What behaviours are common during diel vertical migration

Answer 29

Surface water feeding at night and then descend to depth during the day- conserve energy in colder waters during the day

Question 30

Diel

Answer 30

24 hour rhythm- nocturnal migration

Question 31

Ephausiids in the California Current

Answer 31

-> Night 0-120m- epipelagic
-> Day: Adults at 350-600m ; upper mesopelagic
-> Juveniles shallower during the day : 250-400m

Question 32

Seasonal vertical migration

Answer 32

Vertical migration patterns change seasonally, associated with breeding cycle and food availability, e.g. calanoid copepods