Phylum Dinophyta (Dinoflagellates)

Unicellular aquatic organisms bearing two dissimilar flagella and having characteristics of both plants and animals.

1. Phylum Dinophyta
Dinoflagellates
Presented by:
Fasama Hilton Kollie
Lecturer, Department of Biology
Mother Patern College of Health Sciences February 25, 2019

2. *Overview of the phylum Dinophyta
*Characteristic of dinoflagellates
*Other Forms of life
*Algae bloom
*Biolumenescence
Lesson Outline

3. •Upon completion of this lesson, students will be able to;
1.Define the term Dinoflagellates
2.Describe the basic life processes of organism in the phylum
Dinophyta
3.Identify other live forms relevant to the study of dinoflagellates
4.Identify some ecological and economic importance of
dinoflagellates
Lesson Objectives

4. What are Dinoflagellates?

5. •Unicellular aquatic organisms bearing two dissimilar flagella and having
characteristics of both plants and animals
•From Greek dinos, meaning “whirling” and Latin flagellum "whip, scourge“
•Botanist treated them as a division of algae, named Pyrrophyta after the
bioluminescent forms
Overview of The Phylum Dinophyta

6. •Chlorophyll a, c and carotenoid
•Consist of 130 genera and appx. 3,000
living dinoflagellate species
•Examples include; Gonyaulax, Kerenia,
Noctiluca, Lingulodinium, Oxyrrhis,
Alexandriu, Dinopysis etc
•Many are microscopic and range from
15 – 40 microns in size
Overview Cont’d…
Noctiluca scintillans

7. Dinoflagellates Examples:

8. •90% of all dinoflagellates are marine planktons
Characteristics: Habitat
•They are found dispersed in all
oceans and all ocean zones
•They exist in pelagic or benthic
zones or within host tissues.

9. Oceanic Zones:

11. •Each dinoflagellate has its own characteristic
shape
•Dinoflagellates have a complex cell covering
called an Amphiesma, composed of flattened
vesicles, called alveoli
•In most dinoflagellates, this covering
consists of cellulose plates referred to as
“armor” - THECA
•Other are “naked”
Characteristics: Structure

12. Dinoflagellate Structure

13. •Dinoflagellates have two dissimilar flagella which lies within two
grooves in plates
•Longitudinal Flagellum  
•Transverse Flagellum
Structure Cont’d…

14. •The cytoplasm of dinoflagellates contains typical eukaryotic organelles
•Dinoflagellates may also contain
one or several distinctive
organelles;
•Vacuole
•Pusule
•Cytostome
•Ocellus
•Dinokaryon
•Pyrenoid
•Plastids
Structure Cont’d…

15. Chloroplasts:
•Bound by three membranes and
contain chlorophyll a and c and
fucoxanthin, as well as other
accessory pigments
•Few have chloroplasts with
different pigmentation and
structure
Structure Cont’d…

16. •Locomote by two separate flagella;
longitudinal and transverse flagellum
•Flagella enable them to move in a lateral
circle around the equator of the organism
•In many forms, these are set into grooves
called the sulcus and cingulum
Characteristic: Locomotion

17. Representation of Dinoflagellates:

18. •Three nutritional strategies are seen in dinoglagellates;
•Phototrophy, Mixotrophy and Heterotrophy
•About half of all dinoflagellates species are photosynthetic or mixotrophic
•Some are predators and feed on bacteria, phytoplankton and smaller
dinoflagellates
•Some species establish symbiotic relationship with some invertebrates.
•Eg; zooxanthellae
Characteristic: Nutrition

19. •Zooxanthellae are endosymbionts of marine animals and protozoa
Zooxanthellae:
•Algae in the coral polyp produce
O
2
and organic products for the
polyp
•Coral polyps produce CO
2
for
the algae and it provides
protection in return

20. Anatomy of a
Coral Polyp

21. •Gas exchange occurs
directly through their cell
wall
•Amphiesma vesicle
Characteristic: Respiration

22. •Dinoflagellates are able to get rid of waste by the tiny holes that are
found in the cell wall
Characteristic: Excretion

23. •Dinoflagellates essentially have two means of reproduction
•Sexual division
•Asexual division
•Most are haploid and reproduce primarily by asexual cell division
(mitosis)
•This results in two identical copies of the dinoflagellate
Reproduction

24. •Sexual reproduction also occurs through fusion of two
individuals to form a zygote
•May remain mobile in typical dinoflagellate form
•May form a resting cyst, which later undergoes meiosis
to produce new haploid cells
Reproduction Cont’d…

25. •Dinoflagellates Bloom (Red tide)
•Saxitoxin
•Bioluminescence
Other Features of Dinoflagellates

26. •The rapid increase in the population of dinoflagellate in fresh water or
marine water system
•This is recognized by the discoloration in the water from their pigments
•Dinoflagellates cause a strange phenomenon called “Red Tide”
•Some dinoflagellates produce neurotoxins (Saxitoxin) harmful to marine
life
Dinoflagellate Blooms
Why should we humans be careful so much about dinoflagellates?

28. •The marine animals that feed on dinoflagellates consume the neurotoxins,
which can result in massive death in fish, shellfish, and any other marine life.
Dinoflagellate Blooms Cont’d…

30. •The emission of light by a living organism as a result
of a chemical reaction
•Enzyme-catalyzed reaction
•It’s an enzyme-mediated reaction
•Most marine light-emission is in the blue and green
light spectrum
•Eg: Dinoflagellates, angler fish and others
•Non-marine bioluminescence is less widely
distributed
•The two best-known forms of land
bioluminescence are fireflies and glow worms
Bioluminescence
Fig 1.1 Photinus
pyralis

31. Mechanism of Bioluminescence
In bioluminescence, a
luciferin produces light, and a
luciferase allows the light-
producing chemical reaction
to take place
In this reaction, the
luciferace acts as a catalyst

32. Mechanism of Bioluminescence Cont’d…
luciferase allows oxygen
to combine with the
luciferin
This reaction produces
photons of light…

33. BIOLUMINESCENCE CAUSED BY DINOFLAGELLATES
Vadhoo Island, Maldives

39. 1.Dinoflagellate bioluminescence is also thought to act as a “burglar alarm” to
attract a secondary predator that threatens to eat the primary predator
2.Attracting mates
3.Communication
Function of Bioluminscence

40. Review Questions
1.What are dinoflagellates?
2.What is bioluminescence?
3.What is algae bloom?
4.Briefly describe dinoflagellates

41. Reference
•Nabors, Murray W., INTRODUCTION TO BOTANY. Copyright 2004 Pearson
Education, Inc., publishing as Benjamin Cummings, 1301 Sansome St., San
Francisco, CA 94111. www.aw-bc.com
•Ucsb Scienceline
http://www.scienceline.ucsb.edu/getkey.php?key=3231

42. Thank You
“The mark of a great man is one who knows when to set aside
the important things in order to accomplish the vital ones."
Brandon Sanderson