lecture 8 (dinoflagellates) Flashcards
what is the ecological importance of dinoflagellates?
They form very dense blooms, some of the largest phytoplankton
what is the characteristic movement type of dinoflagellates?
rotary swimming using 2 flagella
what organism is responsible for red tides
dinoflagellates
how are dinoflagellates fossilized?
they form a resistant dormant cyst which can accumulate in sediments
based on cell covering characteristics, what is the difference between thecate and athecate dinoflagellates?
thecate = armoured, contain internal thecal plates made of cellulose
athecate = unarmoured, thecal vesicles are empty
what is a thecal plate made of
cellulose
what are the two halves of an unarmoured dinoflagellate called?
epicone (top), hypocone (bottom)
what is an amphiesmal?
the vesicle under the cell membrane of dinoflagellates (also called thecal vesicles)
what are the morphological differences between a desmokont and dinokont cell?
desmokont = 2 large cell plates (valves) and two dissimilar flagella at cell apex
dinokont = typical dinoflagellates, divided into two halves (apical and posterior), separated by a cingulum
how fast does a dinoflagellate swim
200-500 um/s
what is the pustule? what is its function?
an branched sac/tubules that opens into the vicinity of flagella.
function = excretion, osmoregulation and maybe uptake
what pigments do dinoflagellates have?
chl a, chl c, b-carotene, and a unique xanthophyll (peridinin)
storage of dinoflagellates
starch grains
describe motility in dinokont dinoflagellates
transverse flagellum in the cingulum that provides 50% of swimming speed and rotation
longitudinal flagellum that lies in the sulcus, provides 50% of forward swimming speed and steering
define trichocysts and their function
present in almost all dinoflagellates. A vesicle with ejectile protein rods at the cell periphery.
function: defense, escape from predators
define scintillon and function
allow for bioluminescence under pH decrease, located intracellularly, at the cell periphery.
function = protection against predation, startles predator, makes predators more visible
define peridinin
a unique accessory xanthophyll in dinoflagellates
define sulcus
the groove that holds the longitudinal flagella
define zooxanthellae
dinoflagellates who form a symbiotic relationship with coral polyps
define planozygote
a flagellated zygote of dinoflagellates
define hyponozygote
non-flagellated zygote of dinoflagellates
equation for bioluminescence
luciferin + O2 ->(using luciferase enzyme to oxydize)-> oxyluciferin + light
describe the life cycle of dinoflagellates
asexual and sexual reproduction
vegetative (haploid) dino can undergo asexual reproduction/form temporary cysts, or undergo sexual reproduction and release haploid gametes. gametes fertilize and become a 2N planozygote with 2 longitudinal flagella. then this can undergo meiosis and become a N adult or not and be a 2N hypnozygote (cyst like, no flagella) . This hyponozygote can undergo meiosis to be an N adult, or not and become a 2N planozygote again before undergoing meiosis and becoming a vegetative N adult.
what is the role of cyst formation in survival/dispersal of dinoflagellates?
often due to nutrient, irradiance, photoperiod, or temperature changes. may also follow asexual/sexual reproduction.
can help to survive bad conditions, also can be transported in ship ballast water
do dinoflagellates undergo diel vertical migration?
yes
why do dinoflagellates outcompete most other phytoplankton in well-stratified waters at the end of the growing season?
wide nutritional capabilities, but has efficient flagella motion (can do positive phototaxis to move towards light/nutrients), can store a large amount of phosphorus
what are some struggles dinoflagellates face in terms of getting nutrients
low SA:V ratio (low rate of nutrient uptake)
vulnerable to turbulence (will encyst and fall to the bottom)
what is the cyst phase of dinoflagellates called
hypnzygote
