Lecture 6- zooplankton

Question 1

what are the three aquatic environments for invertebrates?

Answer 1

• water (planktonic)
• hard surface (attatched)
• soft sediment (benthic)

Question 2

what is the difference between metazooplankton and phytoplankton?

Answer 2

-metazooplankton= planktonic invertebrate organisms

phytoplankton=planktonic algae

Question 3

what are the three major metazoplankton groups?

Answer 3

• cladocerans
• rotifers
• copepods

Question 4

how does metazoplankton distribution differ between oceans and freshwater systems?

Answer 4

-rotifers and cladocerans are limited in marine settings, but abundant in others

Question 5

describe the size of rotifers

Answer 5

-the smallest of all metazooplankton, going from 100-400 micometers in length

Question 6

describe rotifer body divisions

Answer 6

-divided into: head, trunk, foot

Question 7

what do rotifers use cillia for?

Answer 7

-rotifers have retained their cillia and utilise it for the movement of water and food towards their mouths. this way of acquiring food is similar to cillia

Question 8

what type of feeders are rotifers?

Answer 8

filter feeders

Question 9

how do rotifers acquire oxygen? why?

Answer 9

-via diffusion from the water due to a lack of a permanent heart or circulation system

Question 10

how does the rotifer digestive system function?

Answer 10

-they have alimentary canals, so are able to take food in at the mouth, extract nutrients and expel it at the anus. they have kidneys and bladder so can urinate

Question 11

in summary, what features do rotifers posses, and which are they lacking?

Answer 11

have:
-alimentary canals
-kidneys
-bladder
-cillias
-permenant gut
lack:
-heart and circulation system

Question 12

what do rotifers feed on?

Answer 12

• cilliates (main competitors)
• cyanobacteria
• protezoa
• small rotifers and crustaceans (large rotifers)

Question 13

how do rotifers protect against predation? what is the other purpose?

Answer 13

-they produce Loricas out of KYTIN. these protect from predators and also increase flotation

Question 14

how do rotifers form communities?

Answer 14

-they use their cillia to attach to one another and float through the water column

Question 15

what are the three different rotifer forms?

Answer 15

• keratella
• kellicottia
• synchaeta

Question 16

describe cladoceran size and body characteristics

Answer 16

• soft bodied
• 2-5mm in length
• they have an outer covering called a CARAPACE, but are transparent
• filtering legs are not covered

Question 17

what advantage does having a circulatory system give cladocerans?

Answer 17

-they are able to enter the anaerobic zone when food is scarce. to do so they must increase blood hemoglobin levels.

Question 18

how do cladocerans feed and what do they most commonly feed on?

Answer 18

• they are filter feeders, using their legs to bring prey towards them (by generating currents)
• they feed on the microbial loop

Question 19

what features do cladocerans posses which rotifers lack?

Answer 19

• compound eyes

- circulatory systems

Question 20

how do rotifers and caldocerans reproduce?

Answer 20

-PARTHONEGENSIS

Question 21

what determines whether sexual or asexual reproduction occurs in cladoceran and rotifer reproduction?

Answer 21

-whether the environmental conditions are favorable or unfavorable

Question 22

why do rotifers and cladocerans reproduce asexually in favorable conditions? explain how this is carried out

Answer 22

• reproduce asexually to avoid time finding a mate
• produced eggs are carried externally in rotifers and in brood pouches for cladocerans-
• the population is 100% female, as its females producing clones

Question 23

explain cladoceran and rotifer reproduction in unfavorable conditions?

Answer 23

• produce 2 eggs (lesser clutch) via sexual reproduction
• brood pouches undergo EPHIPPIUM (they harden to protect eggs)
• the ephippium is ejected of the back of the mammal, and will remain unhatched on substrates until conditions are favorable again

Question 24

what morphological adaption do male rotifer and cladocerans have?

Answer 24

-they have no mouths and cant feed, providing no competition to females in the unfavorable conditions

Question 25

exaplin the difference between mictic and amictic caldoceran and rotifer females

Answer 25

-amicitic females produce diploid (2 copies of each chromosome) amicitic eggs in favourable conditions
mictic females produce haploid mictic eggs in unfavorable conditions, which are then fertilized by male sperm, to produce a diploid female

Question 26

which two metazooplankton have a carapace?

Answer 26

-cladocerans and copepods

Question 27

describe copepod bodies and body size

Answer 27

• 2-5 mm in length
• same internal structures as caldocerans, but NOT TRANSPARENT
• antenna used for environmental detection and protection
• large legs used for grabbing prey (raptoral feeders)

Question 28

how do copepods reproduce? explain it

Answer 28

• copepods ALWAYS reproduce sexually
• females mate once in their lifetime, and store the acquired sperm.this is then tapped into” when the females want to mate
• this is done to reduce the time consumption of finding a mate

Question 29

how many development stages do copepod offspring go through?

Answer 29

-6 development stages

Question 30

describe the different feeding strategies between cyclopoid and calanoid copepods

Answer 30

cyclopoid copepod:
-raptorial feeders,with large egg sacks
-feed on algae, large protezoa and small cladocerans
Calanoid copepods:
-huge antenna, one egg dack
-raptorial and filter feeders
-feed on algae, small protezoa (raptorially), bacteria and protists (filter feed)