Zooplankton Flashcards
Zooplankton
Planktonic Organisms. Protists or metazoans (multicellular, with cells differentiated into tissues, organs, digestive cavity)
What do phytoplankton feed on
Phytoplankton, other zooplankton or detritus ; heterotrophic
Microzooplankton
<200μm
Macrozooplankton >2mm
Mesozooplankton
0.2-20mm
Herbivores
Feed exclusively on phytoplankton
Detrivores: feed on detritus
Omnivores: feed on phytoplankton and zooplankton
Carnivores
Feed primarily on other zooplankton
Holoplankton
Planktonic throughout life cycle
Meroplankton
Spend part of their life cycle as plankton before/after being nekton or benthos
Holoplankton- Planktonic Foraminifera
- Prosita
- Heterotrophic
- Carbonate shell
- Live in epipelagic and mesopelagic zones
- All environments tropics to poles, species composition varies
- Many have symbionts
Holoplankton- Radiolaria
- 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
Holoplankton- salps (sea grape)
- 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
Holoplankton- Euphausiids- krill
- 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
Holoplankton- Crustaceans - Copepoda
- 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
Holoplankton- Crustacean- Ostracoda
- 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
Holoplankton- Gastropoda- gelatinous snails
- 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
Holoplankton- Marine planktonic worms
- carnivorous- prey on planktonic animals
- Hermaphroditic - carry eggs and sperm
Meroplankton to nekton
Spend part of their life cycle as plankton before/after being nekton or benthos e.g. octopus larvae, larval flounder, squid larvae
Meroplankton from benthos - Jellyfish
- 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
Epipelagic zooplankton: 0-200m
- 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
Epipelagic zoo plankton
0-200m= euphotic and upper dysphotic light zones
Mesopeglagic zooplankton
Twilight (blue and green) to aphotic
Temperature change through thermocline
Decreases to <5 C
Pressure increases mesopelagic zone
1atm/10m
Adaptations of mesopelagic zooplankton
Bioluminescence: light produced and emitted by organisms
Oxidation of organic compounds
Predator defence
Camouflage
Morphological adaptations of mesopelagic zooplankton
Large eyes of marine gastropods give high sensitivity to green-blue wavelengths
Adaptations of bathypelagic (1000-2000m) and abyssalpelagic (2000-6000m)
–>Carnivores and detrivores
–> Deep red/clack
–> Increased bioluminescence
–> Smaller eyes than mesopelagic species
Midsummer zooplankton biomass
Maximum biomass in surface waters/ upper mesopelagic - reduction with depth
Diel Vertical migration
=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
What behaviours are common during diel vertical migration
Surface water feeding at night and then descend to depth during the day- conserve energy in colder waters during the day
Diel
24 hour rhythm- nocturnal migration
Ephausiids in the California Current
-> Night 0-120m- epipelagic
-> Day: Adults at 350-600m ; upper mesopelagic
-> Juveniles shallower during the day : 250-400m
Seasonal vertical migration
Vertical migration patterns change seasonally, associated with breeding cycle and food availability, e.g. calanoid copepods
