The Plankton Community Flashcards
How does sonar work to find plankton in the ocean?
send sound signal into the ocean, and the sound scatters back from objects (eg plankton, fish) it hits
eg fish finders
What is the DSL seen with sonar?
DSL= deep scattering layer
a layer that scatters the sound
- it’s plankton!
- some of the DSL migrates daily
Plankton in the deep scattering layer undergo diel vertical migrations. What does this mean?
they go up in the night, down in the daytime
- this pattern is genetically entrenched in the plankton (like our circadian rhythm)
What are 3 hypotheses for plankton’s diel vertical migrations?
which one has the best evidence?
- predator avoidance- best evidence
- light makes plankton easier to see by predators –> remain deep during the day, surface at night to feed - Metabolic advantage: temperature and food
- conserve energy by feeding in warmer water @ surface at night, and moving deeper at the hotter times of day - Avoid UV damage
- surface waters have high UV light in the day which can damage tissues
t/f
the vertical migration of plankton mixes the upper layer of the ocean
true!
biologically generated turbulence
What’s the difference b/w plankton and nekton?
plankton= too small to be able to swim counter to typical ocean currents (can’t migrate great distances, just crawl/ drift w currents)
nekton= active swimmers, can follow plankton (DSL) and swim against currents
Plankton can be classified in which 2 ways?
- by source of energy
- by how much time spent in the water column
Planktons classified by source of energy:
- phytoplankton: photosynthetic (autotrophic)
- zooplankton: animals (heterotrophic)
- mixoplankton/ mixotrophic: can be photosynthetic but can also ingest other organisms (eg parasite fish)
Planktons classified by how much time they spend in the water column:
give examples for each
- holoplankton= permanent residents (eg krill)
- meroplankton= temporary residents (only spend larval or reproductive life in the plankton) (eg hydrozoan jellyfish)
- neuston= associated with slick (eg phalaropes) feed at tide lines/ laminar circulation
____ and ____ are the main 2 phytoplanktons
___ occur seasonally and _____ appear periodically in huge numbers
diatoms and dinoflagellates
cyanobacteria
coccolithophores
Diatoms:
- are a major type of ___ (in both fresh and marine waters)
- forms a ___ shell, consisting of 2 ____ symmetrical ___
- reproduce by ___ ___
- consumes much of the ___ in the ocean surface
- responsible for ___ of the world’s photosynthesis
algae
silica
radially
valves
binary fission
silica
45%
Dinoflagellates:
- __cellular flagellates
- have an organic shell made of ___
- have __ flagella
- ___ and ___ reproduction
- can be __ trophic and ___ trophic
unicellular
cellulose
2
asexual and sexual
heterotrophic and autotrophic
Which type of plankton cause red tides?
What are red tides?
dinoflagellates, eg noctiluca
Red tides:
- area of huge productivity
- such a huge plankton bloom that it turns the water red
- can be bioluminescent
- often toxic to animals
What are 3 types of green algae found in the ocean? explain each
- cyanobacteria
- abundant
- nitrogen fixation in surface waters - silicoflagellates
- unicellular, biflagellate
- internal skeleton of silica scales
- not coastal- usually found in antarctic and open ocean - coccolithophores
- unicellular nanoplankton
- covered w calcium carbonate plates (coccoliths)
what are coccoliths and where are they found?
What happens to them over time?
calcium carbonate plates (disk shape structure) on the surface of coccolithophores
Coccoliths are shed when they die and deposit on the seafloor
-Blooms are so massive that over time their coccoliths form massive deposits on the seafloor –> compose the white cliffs of dover!
what’s an important function of cyanobacteria in surface waters?
nitrogen fixation!
Crustaceans (zooplankton) have 2 common types. What are they?
- copepods
- euphausids (krill)
Copepods are the most ___ crustaceans in zooplankton
- they have 2 forms: ___ and ___
- have a large medial ___ eye
- major consumers of ____ or smaller _____
- have __ larvae
abundant
planktonic and benthic
phytoplankton or smaller zooplankton
planktonic
Give an example of a planktonic type of copepod
-what are 2 characteristics of it?
Calanoida
- distinguished by a pair of antennae
- 5 pairs of thoracic swimming legs
Which type of zooplankton does the following describe?
- shrimp-like, up to 5cm found more offshore
- abundant in antarctic and in upwelling regions
- main food of baleen whales in the antarctic
- feed on phytoplankton and smaller zooplankton by sieving with setae
Krill!
ie Euphausids of the Crustaceans
Cnidaria are ____
- they have 2 cell layers with a __ skeleton
- ___ for support, buoyancy, and swimming (this is the collagen skeleton)
- have tentacles with stinging organelles= ___
- feed on ____
jellyfish!
collagen
mesoglea
cnidocytes
crustaceans
Cnidaria (jellyfish) have 2 types based on how they move:
1
2
- hydrozoa= use velum to jet swim
- scyphozoan= drifters (mush bigger and les agile)
explain what cnidocytes are and how they work
= specialized organelle of cnidarians
- fires when a hair cilium is triggered, releasing a sticking, piercing, or poison dart into prey
- these are easily replaced
some are very toxic! eg. Portuguese man of war
Ctenophore are a ___ type of zooplankton
- swim with cilia organized into 8 rows of ciliary plates called ___ (=)
- _____ are unique sticky organelles that are fired to trap crustacean prey
carnivorous
ctenes= stiff and can beat through the water like a paddle
colloblast
which type of zooplankton could be the sister organism to all life on earth?
hint- the light refracts off them!
ctenophores
Salps, pyrosomes, and larvaceans are all ____, meaning:
urochordates
= adults are filter feeding but the larvae have a notochord
salps=
urochordates
- tube/ barrel shaped, gelatinous case
- filter water through the tube
pyrosomes=
urochordates
“fire animal”- lights up w stimulus
- colonies of filter feeding tunicates form vast tubes that glide (each tunicate filters)
larvaceans=
urochordates
- build huge mucus houses to feed –> sheds house when it gets clogged and it floats to bottom & gets eaten
- tiny tadpole-like filter feeders
- have a tail to generate feeding current
______ are a type of zooplankton that have a muscular, worm-like body and can swim very fast. They have huge setae teeth and are carnivorous
chaetognaths (arrow worms)
What are pteropods?
zooplankton- “sea butterflies”
- holoplanktonic snails (molluscs)
- swim by wings that project out from the foot
- suspension feed/ are carnivorous
- some have a calcified shell = at risk!
Foraminifera, radiolaria, and ciliates are all ____ _____ that mostly feed on __ ____
unicellular eukaryotes
marine snow
