Planktons and its types, Diatoms and its types, forensic examination and significance.

1. PLANKTONS
https://sealevel.jpl.nasa.gov/files/archive/ac
tivities/ts3ssac3.pdf.
:

2. PLANKTONS
https://sealevel.jpl.nasa.gov/files/archive/ac
tivities/ts3ssac3.pdf.

4. 4
FOO
D
NUTRITION
SIZE
• PYTOPLANKTON
Types of Planktons:
• HETEROTROPHS
• AUTOTROPHS
• ZOOPLANKTON
• MACROPLANKTON
• MESOPLANKTON
• NANOPLANKTON
• MICROPLANKTON
• PICOPLANKTON
• MEGAPLANKTON

5. • Planktonic plants are called phytoplankton.
• The primary importance of these plants, like plants on land, is their ability to
photosynthesize.
• Using chlorophyll, they capture the energy of the sun to make food, releasing
oxygen in the process.
• Virtually, all aquatic life depends upon these microscopic single-celled
organisms for food. Phytoplankton is the main source of food for zooplankton.
• Phytoplankton also contribute a significant portion of the oxygen found in the
air we breathe.
Phytoplanktons:

6. Types of Phytoplanktons:
DIATOMS
https://www.fws.gov/uploadedFiles/Region_8/NWRS/Zone_2/San_Francisco_B
ay_Complex/Don_Edwards_San_Francisco_Bay/Sections/Visit/For_Educators/S
alt_Marsh_Manual_for_Fremont/Updated_Activities/PlanktonLab.2016.pdf.
https://teara.govt.nz/en/plankton/page-1
https://teara.govt.nz/en/plankton/pa
ge-1

8.  During the summer months, mussels or other shellfish eat large
amounts of these dinoflagellates.
 Quarantines are established to prevent people from eating these
shellfish because they would become seriously ill.
 A “plankton bloom” or plankton population explosion, results
when the water is unusually rich in nutrients.
 Some species of dinoflagellates may occur in such numbers that
they color the water a dark red, otherwise known as “red tides.”
 Some red tides may result in the death of large numbers of fish,
because the plankton use up so much oxygen; there is not much
left over for other marine organisms.

9. Img Source https://teara.govt.nz/en/plankton/page-1.

10. Diatoms (Bacillariophyceae)
 Diatoms are microscopic and unicellular.
 Like all plants, diatoms need sunlight. They have various
adaptations to keep them near the surface and near sunlight.
 Increasing surface area is one strategy for retarding sinking.
Diatoms may have long spines, may be round and flat, or
may form long chains.
 Diatoms can also regulate their density. Some contain oils
while others may have a gas bubble inside their bodies.

11. Morphology of Diatoms:
 Each diatom cell is enclosed in a silica case (called the frustule)
which have distinctive shapes and ornamentations.
 The frustule is composed of several parts, namely two valves
(the two might be almost identical or completely different,
varying in shape and ornamentation), which are separated by a
series of silica hoops referred to as the girdle bands.
https://www.fws.gov/uploadedFiles/Region_8/NWRS/Zone_2/San_Francisco_Bay_Complex/Don_Edwards_San_Fra
ncisco_Bay/Sections/Visit/For_Educators/Salt_Marsh_Manual_for_Fremont/Updated_Activities/PlanktonLab.2016.p
df.

12. Img Source https://teara.govt.nz/en/plankton/page-1.

13. Types of Diatoms
 Centrales:
• Valves are circular, polygonal or irregular in outline and with ornamentation on
the wall; ornamentation is radial or concentric about a central point. Valve have
raphae or pseudoraphae. Protoplast with many chromatophores.
• Centrales are more often seen in open sea.
Centrales are divided into three suborders, 9 families, 14 subfamilies and 35
genera.
 Sub order Discoidae: Cells shortly cylindrical, valves circular, hyaline with
radiating striations. Eg. Cyclotella, Melosira, Stephanodiscus
 Sub order Solenoidae: Cells elongate, cylindrical or subcylindrical, complex
girdle with numerous bands. Eg. Rhizosolenia
 Sub order Biddulphiodeae: Cells box shaped, valves with two or more poles
provided with horns or bosses. Eg. Biddulphia, Triceratium

14. Types of Diatoms
 Pennales:
• Valves are bilaterally symmetrical or asymmetrical in surface view. The cell wall
ornamentation is also bilateral with respect to a long line, along the long axis of
cell. Valve always with a raphae or pseudoraphae. Protoplasts with one or two
chromatophores. Pennales are more common in coastal waters.
Pennales are divided into three suborders based on presence or absence of raphae.
These are further classed into 5 families, 10 subfamilies and 28 genera.
 Suborder Araphidae: only pseudoraphae present Family Fragilarioidaea: Valves
mostly straight. Eg. Asterionella, Fragilaria, Synedra, etc
 Suborder Monoraphidiodeae: Shows the beginning of raphe, no central nodule
Family Eunotioideae: Raphae on one or both valves. Eg. Cocconies, Acnanthes,
etc
 Suborder Biraphidiodeae: Shows raphae on both valves, central nodule is present.
Eg. Pleurosigma, Navicula, etc

15. Cyanobacteria
Coccolithophores
https://sealevel.jpl.nasa.gov/files/archive/activities/ts3ssac3.pdf Chlorophyta
Coccolithophores
Classification of
Phytoplanktons

16.  Coccolithophores (Prymnesiophyceae )
• Mostly occur in marine waters. Size ranges between 5 to 20 µm.
• Some have flagella while others are devoid of them.
• They are characterized by possessing two flagella and a fine whip like structure
called haptonema.
• The cells are covered with scales.
• They are two flagellated and filamentous forms with calcified cells.
 Green algae (Chlorophyceae)
• Green algae are microscopic, uniccelluar, some filamentous or colonial,
flagellates or nonflagellates and have chlorophyll a, b and - carotene as light
harvesting pigments.
• Mostly fresh water and saline forms restricted to coastal waters.
• They are widely distributed in tropical waters and few species are found in
Arctic and Antarctic oceans.

17. Planktonic animals are referred
to as zooplankton.
Many zooplankton are able to
move up and down in a water
column, pursuing food and
escaping predators.
ZOOPLANKTONS
1) HOLOPLANKTON
2) MEROPLANKTON
TYPES

18.  Holoplankton
• These organisns spend their entire lives as plankton.
• These organisms can range in size from tiny but abundant
copepods to the extremely large gelatinous cnidarians such as sea
jellies and siphonophores.
• These animals are incredibly important food source for both small
fish such as mackerel and sardines as well as some of the largest
baleen whales
 Radiolarians- unicellular with shells made of silica (glass).
 Foraminifera- have shells made of Calcium Carbonate (CaCO3)

19.  Meroplankton
• These organisms spend only a part of their lives as plankton.
• This group of organisms begins life drifting throughout the sea
until they grow and mature enough to settle in another area.
• This adaptation allows many invertebrates to colonize vast
areas of sea floor and
prevents competition between
parents and offspring.
Img source: The
Australian Museum

20.  Copepods are the most numerous of all animals; they are small
crustaceans that grow to 2 mm long and use their long, sensory
antennae as rudders to direct movement.
 Ostracods are also small crustaceans, with a hinged, two-sided
carapace (shell) that resembles a clam. Their antenna are used
as sensors and to assist in swimming. Ostracods crawl along
surfaces using two pairs of legs with clawed tips.
 Rotifers are almost constantly in motion, beating the cilia at
their heads to move and to bring food to their mouths.When
feeding, rotifers attach themselves to a bit of debris and the
rapid beating of the cilia draws a current of water towards the
mouth.

21. Example
s
Foraminifera
Rotifer
Ostracod
Radiolarians
Fish Larvae
https://sealevel.jpl.nasa.gov/files/archive/act
ivities/ts3ssac3.pdf.
https://www.fws.gov/uploadedFiles/Region_8/NWRS/Zone_
2/San_Francisco_Bay_Complex/Don_Edwards_San_Francis
co_Bay/Sections/Visit/For_Educators/Salt_Marsh_Manual_f
or_Fremont/Updated_Activities/PlanktonLab.2016.pdf.

22. PLANKTONS FOOD PYRAMID
ci.coastal.edu

23. STEP 3 STEP 4 STEP 5
Steps of Planktons Analysis
STEP 1 STEP 2
Collection of
sample from
water bodies
with the help
of dropper
Fixing and
Preservation
with Formalin
or Lugol's
Iodine
Centrifuge
20ml of
aliquot at 1500
rpm for 15
min.
Settle the
water and
separate it
by siphoning
from the top.
Staining is
done by using
Neutral red
and Evan blue
stains.
Observe the sample under Standard Compound Microscope (10x or 12x
Ocular and 10x, 20x, 40x or 100x Objectives) and Inverted Microscope.

24. Diatoms Test
• According to Pollanen, if diatoms are detected in bone marrow then drowning
caused death or was contributing factor and the individual was breathing upon
the entry into the water.
• The diatoms will enter the lungs with the inhalation of any liquid and, if there is
effective cardio-vascular circulation, they can be carried to other internal organs.
• In contrast, if a body is already dead when it is transferred to water, or the cause
of death is other than drowning, then diatoms might still be present in the lungs
but not present in any other internal organ.
• If diatoms are not detected in any internal organs then the cause of death is not
drowning or, if other signs of drowning are present, the drowning may not have
occurred in natural water but in some alternative non-natural source, such as
bathwater or swimming pool.

25. Forensic Significance
• Forensic pathologists discriminate diatom species based on visual examination
of their morphologies and patterns.
• DNA sequencing have been used in diatom testing in drowning cases. DNA
sequencing analyzes the base sequence of a specific DNA fragment, and has the
ability to identify specific species using genetic markers.
• Other phytoplankton in the water (such as cyanobacteria and green algae) can
be detected in human tissue samples from drowning cases by amplifying their
specific DNA regions.
• Diatoms can be used in a range of applications in forensic geoscience. These
include: the matching of environmental samples with items that have been in
contact with water, the investigation of cases of drowning, and the
identification of traces of diatomaceous materials used in the manufacture of
materials or liquids, cause of death.

26. • A, J. PLANKTON IDENTIFICATION. Retrieved 29 October 2020, from
https://teara.govt.nz/en/plankton/page-1.
• Levkov, Z., Tofilovska, S., & Williams, D. (2017). The use of diatoms in
forensic science: advantages and limitations of the diatom test in cases of
drowning. The Micropalaeontological Society. Retrieved 29 October 2020, from
https://www.researchgate.net/profile/Zlatko_Levkov/publication/318108836_Th
e_use_of_diatoms_in_forensic_science_advantages_and_limitations_of_the_dia
tom_test_in_cases_of_drowning/The-use-of-diatoms-in-forensic-science-
advantages-and-limitations-of-the-diatom-test-in-cases-of-drowning.pdf
• Plankton Lab. (2016). [Ebook]. Retrieved 29 October 2020, from
https://www.fws.gov/uploadedFiles/Region_8/NWRS/Zone_2/San_Francisco_B
ay_Complex/Don_Edwards_San_Francisco_Bay/Sections/Visit/For_Educators/
Salt_Marsh_Manual_for_Fremont/Updated_Activities/PlanktonLab.2016.pdf.
REFERENCES:

27. • Plankton Notes. (2020). [Ebook]. Retrieved 29 October 2020, from
https://sealevel.jpl.nasa.gov/files/archive/activities/ts3ssac3.pdf
• R.,, G., Thomas, V., & Varghese, M. Phytoplankton - collection, estimation,
classification and diversity. Retrieved 1 November 2020, from
http://eprints.cmfri.org.in/10409/1/04_Molly_Vargheses1.pdf.
• Zhou, Y., Cao, Y., Huang, J., Deng, K., Ma, K., & Zhang, T. (2020). Research
advances in forensic diatom testing. Forensic Science Research, 5(2).
https://doi.org/10.1080/20961790.2020.1718901
• Cameron, N. (2004). The use of diatom analysis in forensic geoscience.
Geological Society Publications. https://doi.org/10.1144/GSL.SP.2004.232.01.25