Bacillariophyta

Question 1

taxonomy based on?

Answer 1

1. symmetry?
   - bilateral (pennate)
   - radial (centric)
2. ornamentations?
   - Raphe? –> present or not? 1 or both? centric/eccentric?
   - girdle bands –> number/open/closed..?
3. areolae
   - striae? (in rows) –> parallel? radiate? …?
   - loculae? (hexagonal) –> radial? tangential?

Question 2

division of Diatoms from ecological point of view?

Answer 2

Question 3

euplanktonic?

Answer 3

Question 4

benthic?

Answer 4

Question 5

what diatoms constitute the microphytobenthos?

Answer 5

Diatoms settling on natural substrates

Question 6

what diatoms constitute microfouling?

Answer 6

Those that settle on artificial substrates

Question 7

epiphytic diatoms- differentiation, how?

Answer 7

based on how they attach to substrate

adnate vs erect
(whole valve-face vs partial pads or stalks)

Question 8

what’s their attachment?

Answer 8

Question 9

which diatoms can attach?

Answer 9

benthic diatoms or periphyton

Question 10

attachment of benthic diatoms or periphyton: How?

Answer 10

Question 11

attachment of benthic diatoms or periphyton: How?

Answer 11

• pads or stalks

Question 12

attachment of benthic diatoms or periphyton: How?

Answer 12

Question 13

what is that?

Answer 13

Question 14

role of diatoms as benthos?

Answer 14

1. food source
2. Epiphytic diatoms can become part of the food web, as they are eaten by many herbivorous organisms
3. They secrete mucilage forming a biofilm, together with bacteria, which prepares the substrate for the colonization of multicellular algae and sessile animal species

Question 15

what’s the third group of diatoms?

Answer 15

• meroplanktonic or ticopelagic diatoms

Question 16

what are meroplanktonic or ticopelagic diatoms?

Answer 16

• before they were attached benthic forms

Question 17

what do diatoms require for their cell wall?

Answer 17

Question 18

what is composed of silica?

Answer 18

the frustules. ( cell wall)

Question 19

how does availability of SiO2 influence the species composition?

Answer 19

• diff. species –> diff. needs

Question 20

what is diatomaceous earth? how does it develop?

Answer 20

• Frustules of diatoms often do not wear away after the organism death
• accumulate in sediments
• can be preserved as fossils

Diatomaceous earth (diatomite), a silica-containing sedimentary rock, is a collection of diatom frustules found in the earth’s crust.