Lecture 6- zooplankton Flashcards
what are the three aquatic environments for invertebrates?
- water (planktonic)
- hard surface (attatched)
- soft sediment (benthic)
what is the difference between metazooplankton and phytoplankton?
-metazooplankton= planktonic invertebrate organisms
phytoplankton=planktonic algae
what are the three major metazoplankton groups?
- cladocerans
- rotifers
- copepods
how does metazoplankton distribution differ between oceans and freshwater systems?
-rotifers and cladocerans are limited in marine settings, but abundant in others
describe the size of rotifers
-the smallest of all metazooplankton, going from 100-400 micometers in length
describe rotifer body divisions
-divided into: head, trunk, foot
what do rotifers use cillia for?
-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
what type of feeders are rotifers?
filter feeders
how do rotifers acquire oxygen? why?
-via diffusion from the water due to a lack of a permanent heart or circulation system
how does the rotifer digestive system function?
-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
in summary, what features do rotifers posses, and which are they lacking?
have: -alimentary canals -kidneys -bladder -cillias -permenant gut lack: -heart and circulation system
what do rotifers feed on?
- cilliates (main competitors)
- cyanobacteria
- protezoa
- small rotifers and crustaceans (large rotifers)
how do rotifers protect against predation? what is the other purpose?
-they produce Loricas out of KYTIN. these protect from predators and also increase flotation
how do rotifers form communities?
-they use their cillia to attach to one another and float through the water column
what are the three different rotifer forms?
- keratella
- kellicottia
- synchaeta
describe cladoceran size and body characteristics
- soft bodied
- 2-5mm in length
- they have an outer covering called a CARAPACE, but are transparent
- filtering legs are not covered
what advantage does having a circulatory system give cladocerans?
-they are able to enter the anaerobic zone when food is scarce. to do so they must increase blood hemoglobin levels.
how do cladocerans feed and what do they most commonly feed on?
- they are filter feeders, using their legs to bring prey towards them (by generating currents)
- they feed on the microbial loop
what features do cladocerans posses which rotifers lack?
- compound eyes
- circulatory systems
how do rotifers and caldocerans reproduce?
-PARTHONEGENSIS
what determines whether sexual or asexual reproduction occurs in cladoceran and rotifer reproduction?
-whether the environmental conditions are favorable or unfavorable
why do rotifers and cladocerans reproduce asexually in favorable conditions? explain how this is carried out
- 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
explain cladoceran and rotifer reproduction in unfavorable conditions?
- 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
what morphological adaption do male rotifer and cladocerans have?
-they have no mouths and cant feed, providing no competition to females in the unfavorable conditions
