Quiz 3 Lecture 1 Aquatic organisms

Question 1

What does lentic mean?

Answer 1

In still water

Question 2

What does littoral mean?

Answer 2

On lake shores, in shallow benthic zone of lakes

Question 3

What does lotic mean?

Answer 3

in flowing water

Question 4

What does pelagic mean?

Answer 4

in open water

Question 5

What are phytoplankton?

Answer 5

Are photoautotrophs adapted to live in open water and are the base of the aquatic food web

Question 6

Are phytoplankton uni or multicellular?

Answer 6

Phytoplankton are unicellular and multi cellular as they have multiple species

Question 7

Are phytoplankton sexual, sexual, or facultatively sexual?

Answer 7

All of the above, they have multiple species

Question 8

Are phytoplankton prokaryotes or eukaryotes?

Answer 8

Both, cyanobacteria are prokaryotes

Question 9

How long ago did phytoplankton evolve?

Answer 9

700-1500 mya

Question 10

When did phytoplankton diversify?

Answer 10

before the dinosaurs

Question 11

Phytoplankton freshwater forms are polyphyletic, describe what this means?

Answer 11

They are derived from more than one common ancestor

Question 12

What are the problems phytoplanktons face (5)?

Answer 12

There is no solid substrate, sunlight is an essential resource only available near the surface, they need essential nutrients such as N and P which are rare, zooplankton want to eat them, there’s a varying environment.

Question 13

Is there an optimum solution to the problems phytoplankton face?

Answer 13

No, not all solutions can be chosen independently, the solution to one problem could make another worse

Question 14

What adaptations have phytoplankton done?

Answer 14

small size and density and shape

Question 15

What are the benefits of phytoplanktons small size

Answer 15

sink slowly, they have a higher surface area to volume ratio so they have more nutrient uptake, they have a higher division rate making them better competitors

Question 16

What are costs of phytoplanktons small size?

Answer 16

Their easier to eat

Question 17

What things have phytoplankton done when they adapted their density and shape?

Answer 17

They did food storage as lipids, cyanobacteria produces gas vacuoles, they have spines and other elongate shapes

Question 18

What are the benefits of phytoplankton adapted density and shape?

Answer 18

flotation- they stay near the surface and have lower sinkage so more sunlight, they can have a lower predation rate

Question 19

What are the costs of phytoplanktons density and shape?

Answer 19

More lipids results in more zooplankton predation

Question 20

What are the defensive traits phytoplankton have?

Answer 20

toxins, trichocysts (can eject and deter predators), and filamentous and colonial growth

Question 21

What are cyanobacteria (6) characteristics?

Answer 21

True bacteria – prokaryotes
* Bacteria-like but do photosynthesis like plants
* Unicellular, filamentous and colonial form
* Mucus sheaths and toxins – inedible
* have Heterocysts (can fix nitrogen during nitrogen starving cond)
* Gas vacuoles (protein-bound structures containing air to adjust their buoyancy)

Question 22

What are chlorophyta (5) characteristics?

Answer 22

8000 known seperate species making them the most diverse freshwater algae group, paraphalytic (descended from a single evolutionary ancestor), both uni and multi cellular, some species colonial or inducible colonial, filamentous, unicellular species gave two flagella and are motile, they are found in all surface aquatic habitats

Question 23

What are the characteristics of Bacillariophyta? (7)

Answer 23

• Thousands of known species
• Single-celled or colonial
• Most spp. non-motile/sessile; some can secrete mucus to glide over solid surfaces
• Silica opalescent – glass cell wall called frustule. Can be limited in growth by silica
• Siliceous (has silaceous) cell wall perforated by small holes to allow dissolved materials and solids
  in and out
• Shape and lipids help them float, but their density means they sink fast.
• Frustule can be preserved in the sediments for long periods of time, making these
  important for paleolimnological studies

Question 24

What are the characteristics of cryptophyta? (7)

Answer 24

Few species, only 12 genera
* Distinguished by trichocysts
* Tightly coiled protein “springs” that can undergo rapid irreversible conformational shift
* Cell jumps backwards when trichocyst pops out of cell in response to a disturbance
* Unicellular, 2-20 um
* Two flagella; motile
* Most spp. probably mixotrophic (uses diff energy sources: light and eeating)

Question 25

What are the characteristics of dinophyta? (5)

Answer 25

~200 freshwater species
Unicellular, often large
Two flagella, motile (“whirling flagella”)
Many spp. Mixotrophic (able to ingest other organisms)
Many spp. have armored plates made of cellulose

Question 26

What are the characteristics of euglenophyta?

Answer 26

can be pigmented or colorless,
autotrophic or heterotrophic. Red photosensitive spot in one end

Question 27

What are the characteristics of desmidiales?

Answer 27

order of charophyte a division of green
algae, common in freshwater

Question 28

What are the characteristics of chrysophyta?

Answer 28

have two flagella, can ingest other
organisms for food. Facultative heterotrophs. Dinobryon (bottom
right) forms chain-like colonies that makes it difficult for herbivores
to consume. Colony can swim in a directed fashion well enough to
stay in the photic zone .

Question 29

What are mixotrophic phytoplankton?

Answer 29

They obtain nutrients from both autotrophy and hetereotrophy and switche when advantageous

Question 30

What is the cost to being abale to switch modes of aquiring energy in mixotrophic phytoplankton?

Answer 30

Can only be autotrophs in low light and can only be heterotrophs when there’s high bacterial prey availability

Question 31

What are the ecological consequences of phytoplankton adaptations?

Answer 31

Variation in phytoplankton biomass over time and space (seasonally, with depth, among lakes…)
Variation in phytoplankton diversity (how many species)
Variation in phytoplankton species composition (which species)
Variation in primary productivity
Links to zooplankton, rest of food web (if they change their pred zooplankton changes and then rest of the food web changes).

Question 32

What are zooplankton and why are they important?

Answer 32

Zooplankton are animal wanderers, they limit algae and phytoplankton through grazing- thereby affecting water clarity
-They support higher food webs
-They impact carbon cycles

Question 33

Describe protists (6) characteristics?

Answer 33

Single-celled heterotrophic eukaryotes
smallest zooplankton
abundant
mostly bacterivores

Question 34

Describe rotifers (5) characteristics?

Answer 34

Are wheel animals, have the smallest multicellular organisms, feed on bacteria, small algae, and other rotifers, like protists are most common in the littoral zone, have sexual and asexual reproduction (mostly pathenogenesis- reproduction that involves development of female gamete without fertilization)

Question 35

Describe cladocera (4) characteristics?

Answer 35

order of crustaceans, filter feed and primarily eat algae, larger species can eat a large size range of algae- daphnia are the dominant lagal grazers
have mostly cyclical parthogenesis
the vulnerbaility to predation is determined their size, transparency, and defenses for example (cyclomorphosis (morphological changes that occur seasonally or cyclically and diel vertical migration (daily movemeent up and down water column)

Question 36

Describe Copepoda? (6 characteristics)

Answer 36

Subclass of crustaceans
Two main freshwater orders
◦ calanoid (planktonic herbivores)
◦ cyclopoid (littoral predators)
Most species 1-2 mm long
Sexual reproduction
Raptorial (catch algal cells one at a time)
Many species have fast escape responses