Haptophytes and Diatoms Flashcards
how many species of haptophyta and diatoms are there
H = 300 species
D = 9000 species
outline some characteristics of haptophyta
kingdom = chromista
primarily marine phytoplankton
what is a haptonema
thread like structures which extends from the cell along with 2 flagella of equal length used to capture prey
what are two important haptophyte species
1) pavlovophyceae = food for bivalves
2) isochyrysis = used in hair products for pigemnts
outline some characteristics of haptophyte scales
composed of calcified organic material called coccoliths
what are cocclithophorids
the happtophyte families which have coccoliths which are highly reflective
what is E.hyxleyi
a species of phytoplankton which forms blooms which are then attacked and destroyed by viruses recycling inorganic caco3
in haptophytes what is the plastid surrounded by
a chloroplast endoplasmic reticulumn continous with the nuclear envelope
how are haptophytes ecologically significant
- significant components of food webs
- consumers, grazing on DOC and cyanobacteria
- transport organic C
- important for global carbon cycling
what is DMS
a volitle sulphur compound which affects atmospheric chemistry and global climate
after UV degredation it forms cloud condesnsation nucli forming clouds
what is polysaccharide mucilage
a foam which clogs fishing nets but adds organic carbon to water
what does the colonial stage of the phaeocystis species of haptophyte contribute
dominated phyto plankton of marhinal ice contributing to 10% of atmospheric phytoplanton sulphur compounds
outline some characteristics of diatoms
kingdom= chromista
have heterokont = different flagella
one is tinsel and one is whiplash
when did diatoms first appear
250 million years ago
outline the structure of a diatoms cell wall
cell wall - frustule in two overlapping parts
the frustule made of silica with miunte intricate depressions, pores and pathways which connetc with living protoplasm within to the outside enviro
what are the two major types of diatom
1) pennate - has bilateral symmetry
2) centric - has radial symmetry = large SA:V so float easier
outline some characteristics of the life history of a diatom
- form resting cells in unfavourable conditions which sink
- germinate when conditions improbe
- most abundant in spring and atutum
outline the diatom plastid
conatins chlorophyll a and c masked by a pigment fucoxanthin
what is the reserve storage material in diatoms
lipids
water soluable polysaccharide chrysolaminarin
what are the diatom feeding mechanisms
most = autotrophic
some heterotrophic= usually pennate diatoms
some live simbiotically in large marine protozoa = formaminiferans
what is the ecological significance of diatoms
- primary food source
- rich in carbs and fatty acids
- some produce a neurotozin causing amnesiac shellfish poisoning
what is the importance of macroalgae
acts as a home and nursery grounds
important for biodiversity
bioindicators of chemical change
how can macroalgae act as a cover
stabalise areas by decreasing wave action
minimise sand abrasion
act as camoflage for some species
outline the position of some macroalgae in different zones of rocky shores
red = lower down shore as bad at dessication
greens = upper shore
browns = very common at depths
what factors affect zonation
- high exposure the zonation spreads over greater height
- ability to survive desication
- survival of osmotic shock
- abrasion resistance
- felxibility and strength against wave action
