Dinoflagellates

Question 1

Answer 1

Desmokont

Based on the different position of the flagella dinoflagellates can be divided into two cell types:
Desmokont and Dinokont

Question 2

Answer 2

Dinokont

Based on the different position of the flagella dinoflagellates can be divided into two cell types:
Desmokont and Dinokont

Question 3

Answer 3

The transverse flagellum is constituted by an axoneme arranged in a spiral; the axoneme is flanked by a striated strand. Axoneme and striated strand are both enveloped by a sheath.

The contraction of the striated strand causes an increase in the spiral coil of the flagellum and determines a downward motion.

Question 4

Answer 4

a: undischarged trichocyst
b: discharged trichocyst

On the surface of the cell there are trichocysts, elongated protein structures, arranged on the periphery of the cell.

After stimulation trichocysts discharge explosively outside the cell.
The discharge of the trichocysts results in a rapid movement of the cell in the opposite direction to the discharge.
Their function may be to allow escape from predators

Question 5

Answer 5

Theca of DESMOKONT: cells have only two large plates

Question 6

Answer 6

Theca of DESMOKONT CELLS:
Exhibit two flagella located in the apical part of the cells

Question 7

Answer 7

Desmokont cells

Question 8

Answer 8

Desmokont cells

Question 9

Answer 9

Example of “nude” Dinokont cell

Question 10

Answer 10

Example of “armoured” Dinokont cell

Question 11

Answer 11

Cell structure

Question 12

Answer 12

Dinokont cell: Two flagella emerge at the intersection of the transverse and longitudinal grooves (ventral side)

The transverse flagellum, ribbon-like, lies in an equatorial groove, called cingulum, surrounding the cell

the longitudinal flagellum extends backwards through a depression, called sulcus

The cingulum divides the typical dinokont cell into an epicone and a hypocone

Question 13

Answer 13

Dinokont cells: Protoperidinium divergens

Question 14

Answer 14

Dinokont cells: Protoperidinium steinii

Question 15

Answer 15

Dinokont cells:
Some Dinoflagellates are characterized by the presence of several horns (e.g. Ceratium). The apical half of the cell is usually characterized by a single horn, while the antapical half can have one, two or even three horns (e.g. Ceratium hirundinella).

Question 16

Answer 16

Tabulation theca

Question 17

Answer 17

Dinoflagellates have various types of pyrenoids.
For example, in the species of the genera Glenodinium and Aureodinium, the pyrenoid is pear-shaped, protruding from the chloroplast. In other cases the pyrenoid can be immersed in the chloroplast.

Question 18

Answer 18

Red tides

Dense blooms of planktonic dinoflagellates
can result in a visible colour of the water to brown, red or green