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Dinoflagellates
Introduction
Dinoflagellates are unicellular, flagellated protists
– The first modern dinoflagellate was described by Baker in 1753
– The dinoflagellates were first defined by Otto Bütschli in 1885 as
the flagellate order Dinoflagellida. Botanists treated them as a
division of algae, named Pyrrhophyta after the bioluminescent
forms. They have also been called the Dinophyta or
Dinoflagellata
– Over 2000 species
– Traditionally classified as algae
– Most are microscopic, but a few reach a diameter of up to 2mm
Evolution
• Dinoflagellates are
considered to be among the
most primitive of the
eukaryotic group, the fossil
record of the group may
extend into the Precambrian
period
• Dinoflagellates are thought to
have evolved from an early
eukaryotic ancestral stock
following the evolution of
repeated DNA
• Combine primitive
characteristics of prokaryotes
and advanced eukaryotic
features
Structure
• All dinoflagellates are
surrounded by a
complex covering
called the amphiesma
– In most dinoflagellates,
this covering consists of
cellulose plates referred
to as “armor”
– Others are “naked”
Gonyaulax polyedra
Karina brevis
Structure
• Dinoflagellates have
two dissimilar flagella
– The transverse flagellum
lies in a groove called the
cingulum and provides
forward motion and spin
– The longitudinal flagellum
lies in a groove called the
sulcus and trails behind
providing some
propulsive force, but
acting mainly as a rudder
Cingulum
Sulcus
Structure
• There are three basic cell extensions:
– Lists
– Horns
– Spines
Horns
Cell Biology
• The cytoplasm of
dinoflagellates contains
typical eukaryotic
organelles
• Dinoflagellates may also
contain one or several
distinctive organelles
–
–
–
–
pusule
eyespot
ocellus
chloroplasts
Cell Biology
• The dinoflagellate nucleus is
unusual:
– Most dinoflagellates are
distinguished by a dinokaryon,
a special eukaryotic nucleus
containing fibrillar
chromosomes that remain
condensed during the cell cycle
and a unique external mitotic
spindle.
– In most dinoflagellates, the
nucleus is dinokaryotic
throughout the entire life cycle.
N
Peridinium spp.
Cell Biology
Chloroplasts:
– bound by three membranes
and contain chlorophylls a
and c and fucoxanthin, as well
as other accessory pigments
– a few have chloroplasts with
different pigmentation and
structure, some with a
nucleus
– dinoflagellate chloroplasts
may be remnants of diatoms
ingested by a heterotrophic
flagellate, which may have
been the ancestor of modern
dinoflagellates.
Ceratium furca
Life Cycle
• Most dinoflagellates are
haploid and reproduce
primarily by asexual cell
division (mitosis)
• 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
Pfiesteria piscicida life cycle
Ecology
• In addition to living in
the open ocean,
dinoflagellates colonize
tidal pools, sediments,
sea-ice environments
and freshwater
ecosystems
• The distribution of
dinocysts may follow
patterns based on
latitude, temperature,
salinity, water depth and
ocean circulation
systems.
Phytoplankton bloom in near Svalbard
in Barents Sea, Aug 13, 2002
Ecology
• Many dinoflagellates
are heterotrophs and
have evolved various
mechanisms to ingest
prey
• Some are autotrophs
• Many species are
capable of both
heterotrophy and
photosynthesis
(mixotrophic)
mixotrophic dinoflagellate Ceratium furca
Ecology
• Some dinoflagellates
are predators and feed
on bacteria,
phytoplankton and
smaller dinoflagellates
• Some target larger prey,
such as copepods,
crustaceans and fish
Ingestion of cryptophytes by G. galatheanum,
brightfield (movie)
Ecology
• Some dinoflagellate
species, called
zooxanthellae, are
endosymbionts of marine
animals and protozoa
– lack characteristic armor
and flagella, appear as
spherical,golden-brown
globules in their host
cells
Symbiodinium microadriaticum
• These play an important part in the biology of
coral reefs
–
–
–
–
provide nutrients for coral
accelerate skeletal formation (calcification)
give coral its color
receive shelter in return
• Coral bleaching occurs when reef-building
corals lose their endosymbiotic
dinoflagellates
Oblique Coral, Vadoo Diving
Paradise, Maldives, Feb 1997
Oblique Coral, Vadoo Diving
Paradise, Maldives, Dec 1997
Oblique Coral, Vadoo Diving
Paradise, Maldives, Mar 1999
Ecology
• Dinoflagellate infections
have been reported for
a wide range of host
organisms including
sarcodines, ciliates, free
living dinoflagellates,
various invertebrates,
and a few vertebrates.
• Some dinoflagellates
parasitize other
parasitic dinoflagellates.
Blue crab cardiac tissue infected with Hematodinium spp.
Ecology
• The Dinoflagellata are
sometimes called
Pyrrhophyta (fire plants)
because some species are
capable of bioluminescence.
• Bioluminescent
dinoflagellates begin to glow
as it gets dark, and brighten
considerably when agitated.
• The expression of
bioluminescence is
controlled by an internal
biological rhythm.
Model of circadian rhythm
Noctiluca spp.
Significance
•
Primary Producers
– Important primary
producers in both
marine (particularly
on-shore) and
freshwater
environments
Significance
• Harmful Algal Blooms
– occur when a dinoflagellate species multiplies until it
dominates the phytoplankton community - high
concentrations cause the water to become discolored
– often called "red tides" but can also appear green, yellow, or
brown, depending on the type of dinoflagellate involved
– considered harmful because dinoflagellates produce potent
toxins
– blooms can kill fish and other marine organisms, poison
people who eat contaminated shellfish, and cause
respiratory distress in susceptible people
Florida Red Tide Bloom of
Gymnodinium breve
Fish kill caused by Ceratium furca and Prorocentrum
micans. 60 tons of lobster and 1500 tons of fish washed
up on shore on West African west coast, Mar 1994.
• Types of dinoflagellate related illnesses
(human):
– Diarrhetic Shellfish Poisoning (DSP): considered by
some scientists to be the most common and globally
widespread phytoplankton related seafood illness.
– Neurotoxic Shellfish Poisoning (NSP): gastrointestinal
and neurological symptoms from eating shellfish that
have fed on toxic Karenia brevis dinoflagellates
– Paralytic Shellfish Poisoning (PSP): PSP syndrome is
life-threatening and can result in respiratory arrest
within 24 hours of consuming shellfish laced with toxins
from feeding on Alexandrium spp.
– Ciguatera fish poisoning (CFP): Ciguatera fish
poisoning is caused by biotoxins produced by
dinoflagellates that grow on seaweeds and other
surfaces in coral reef communities.
• Pfiesteria piscicida
– normally exists in non-toxic forms, feeding on algae
and bacteria in the water and in sediments of tidal
rivers and estuaries
– becomes toxic in the presence of fish, particularly
schooling fish, triggered by their secretions or
excrement in the water
– Pfiesteria cells shift forms and emit a toxin that stuns
the fish, emits other toxins that break down fish skin
tissue, causing bleeding sores
– As fish are incapacitated, the Pfiesteria cells feed on
their tissues and blood
– implicated as a cause of major fish kills at many sites
along the North Carolina coast
Pfiesteria piscicida lesions on crab and fish
Nessie's Diet of Deadly Dinoflagellates
The Loch Ness Exploration Program has uncovered an exciting new theory to explain
sightings of the famous Nessie monster.
Professor Arnold Stryker (33) of the International Marine Biology and Oceanographic
Diversity Research Project (on secondment to the Loch Ness Exploration Program) has
located an ancient organism called Pfiesteria at 8 different points in the loch.
"I did not expect to find this creature in such concentrations - it is a revolutionary discovery."
Pfiesteria is part of a group of pre-historic organisms called dinoflagellates.
Dr. Gunter Fishlin PhD (44) said "our Loch Ness Exploration Program has been looking for
evidence of unknown creatures living in Loch Ness. We now believe that, while firm
evidence of a large dinosaur living beneath the waves still eludes us, we have at least
established the presence of dinoflagellates.
Pfesteria is a peculiar organism. It groups together with its fellows to form large clumps of
slime. This slime actually displays "ambush-predator" qualities by attacking fish. As schools
of fish build up in an area Pfiesteria starts secreting toxins which overcome them. The fish
die from suffocation as their nervous system collapses and their skin tissue starts to break
down under the impact of the toxin.
The interesting link for Loch Ness researches investigating the possibility of a large
plesiosaur living in the depths is Pfiesteria's effects on humans. Dr. Fishlin explains "many
eye-witnesses have come forward with accounts of their sightings of the Loch Ness
monster, some of which include references to feelings of "lost time" that thy cannot explain.
The toxins given off by Pfiesteria are hallucinogenic and research elsewhere has shown that
a feeling of lost time is a common side effect.
Are humans around Loch Ness at risk from "the cells from hell"? Professor Stryker doesn't
think so: "as long as people are aware of its dangers and avoid parts of the loch where they
see large clumps of algae-like slime, they should be safe.
• Ciguatera poisoning
– subtropical and tropical
marine finfish accumulate
naturally occurring
dinoflagellate toxins through
their diet
– most common nonbacterial,
fish-borne poisoning in the
United States
– ciguatera poisoning in
humans usually involves a
combination of
gastrointestinal,
neurological, and
cardiovascular disorders
• Every coastal state
has reported major
blooms
• Blooms may be
responsible for more
than $1 billion in
losses during the
last two decades
• What causes HABs?
– Marine transportation
may have contributed to
the global HAB
expansion by
transporting toxic species
in ballast water
– aquaculture activities
may be related to HAB
expansion
– Increased nutrient loads
to coastal waters may
stimulate HAB species
populations to initiate a
bloom
A large sediment plume flowing out to
sea and associated phytoplankton
bloom offshore. Brazil, 2000.
Sources
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http://www.ucmp.berkeley.edu/protista/dinoflagellata.html
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ellates.html
http://en.wikipedia.org/wiki/Dinoflagellates
http://visibleearth.nasa.gov/
http://www.searay.50megs.com/hematod.html
http://coral.s5.com/
http://www.eeb.uconn.edu/Courses/EEB290/Lecture26.pdf
http://www.emedicine.com/emerg/topic100.htm
http://www.habhrca.noaa.gov/
http://www.habhrca.noaa.gov/habfacts.html
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http://www.sustainablefishery.org/index.html
http://geo.ucalgary.ca/~macrae/Dinoflag_spindles.gif
http://www.lochness.co.uk/exhibition/dinoflagellates.html