1.
Diatoms/Dinoflaellets/Zooplanktons
COF/NAU/AEN 201/Bhautik Savaliya/2016-17 Page 1
DIATOMS
1.Genus: Coscinodiscus
Classification:
 Kingdom -Chromalveolata
 Subphylum – Bacillariophyceae
 Class - Coscinodiscophyceae
 Order -Coscinodiscales
 Family - Coscinodiscaceae
 Genus –Coscinodiscus
Description: Cells are disc-shaped, cylindrical or wedge-shaped, and solitary distinct
rosette of large areolae in the center of the valve. Numerous chloroplasts.
Cell size: Diameter (apical axis) = 30-500 µm
Distribution: Widespread - warm water to boreal.
Interesting facts: Usually regarded as one of the largest marine planktonic diatom
genera.

2.
Diatoms/Dinoflaellets/Zooplanktons
COF/NAU/AEN 201/Bhautik Savaliya/2016-17 Page 2
2.Genus: Ditylum
Classification:
 Kingdom - Chromalveolata
 Phylum - Heterokontophyta
 Class - Coscinodiscophyceae
 Order - Lithodesmiales
 Family - Lithodesmiaceae
 Genus – Ditylum
Looks like: Rolling pin
Description: Found as single cells or short chains. Numerous, small chloroplasts, a
long central spine, produce resting spores.
Cell size: Length (pervalvar axis) = 80-130µm
Distribution: Cosmopolitan except in polar waters.

3.
Diatoms/Dinoflaellets/Zooplanktons
COF/NAU/AEN 201/Bhautik Savaliya/2016-17 Page 3
3.Genus: Eucampia
Classification:
 Empire-Eukaryota
 Kingdom-Chromista
 Phylum-Bacillariophyta
 Subphylum-Bacillariophytina
 Class-Mediophyceae
 Subclass-Biddulphiophycidae
 Order-Biddulphiales
 Family-Biddulphiaceae
 Genus-Eucampia
Description: Flattened elliptical cells (in valve view) that form spiral, curved chains.
Cells joined by flattened apical horns.
Cell size: Length (apical axis) = 10-61um
Distribution: Cosmopolitan, excluding polar regions

4.
Diatoms/Dinoflaellets/Zooplanktons
COF/NAU/AEN 201/Bhautik Savaliya/2016-17 Page 4
4.Genus: Guinardia
Classification:
 Kingdom - Chromista
 Phylum - Bacillariophyta
 Class - Coscinodiscophyceae
 Order - Rhizosoleniales
 Family - Rhizosoleniaceae
 Genus – Guinardia
Description: Cylindrical cells that form straight, curving and sometimes spiraling
chains. Valves flat but with rounded edges. External process is marginal, and fits into a
shallow depression in adjoining valve. Girdle bands appear as collars but hard to see.
Small numerous chloroplasts.
Cell size: Width = 6-45 µm, Length = 250µm
Distribution: Neritic, widespread, probably cosmopolitan.
Synonym: Rhizosolenia stolterfothii

5.
Diatoms/Dinoflaellets/Zooplanktons
COF/NAU/AEN 201/Bhautik Savaliya/2016-17 Page 5
5. Genus: Leptocylindrus
Classification:
 Kingdom - Chromista
 Phylum - Ochrophyta
 Class - Coscinodiscophyceae
 Order - Leptocylindrales
 Family - Leptocylindraceae
 Genus – Leptocylindrus
Description: Tight chains with abutting valve surfaces. Forms resting spores.
Cell size: Diameter (apical axis) = 5-16um
Distribution: Cosmopolitan
Interesting fact: L. mediterraneus is nearly always found with the epiphytic flagellate
Solenicolasetigera

6.
Diatoms/Dinoflaellets/Zooplanktons
COF/NAU/AEN 201/Bhautik Savaliya/2016-17 Page 6
6. Genus: Pleurosigma
Classification:
 Kingdom - Chromista
 Phylum - Bacillariophyta
 Subphylum - Bacillariophytina
 Class - Bacillariophyceae
 Subclass -Bacillariophycidae
 Order - Naviculales
 Suborder - Naviculineae
 Family - Pleurosigmataceae
Description:
1. Valves sigmoid
2. Raphe sigmoid
3. Striae decussate
Valves are elongate and sigmoid. Striae are composed of evenly spaced decussate
rows. The rows are arranged in 3 patterns: a trans-apical row and two opposing
oblique rows. Internally, the areolae are occluded by hymenes. The raphe is strongly
sigmoid, with a narrow axial area. The sternum is thickened equally on both sides. The
raphe terminates proximally in a small oval, expanded central area defined by two
curved ridges. Proximal raphe ends are slightly inflated and straight, or unilaterally
bent. The distal raphe ends are hooked and deflected to opposite sides on the mantle.
The valve mantle is relatively shallow and the valve / mantle interface is broad and
curved. Two to four ribbon-like plastids extend from apex to apex.

7.
Diatoms/Dinoflaellets/Zooplanktons
COF/NAU/AEN 201/Bhautik Savaliya/2016-17 Page 7
7. Genus: Rhizosolenia
Classification:
 Kingdom - Chromista
 Phylum - Bacillariophyta
 Subphylum - Coscinodiscophytina
 Class - Coscinodiscophyceae
 Order - Rhizosoleniales
 Family - Rhizosoleniaceae
 Genus - Rhizosolenia
Description:
Cells are cylindrical, with conical valves narrowing into a long, straight and needle-
like spine. Cells are much longer than they are wide and valves do not have otaria Cell
frustule is weakly silicified. Rhizosolenia cells are wider in the centre and gently
narrow towards either end. Cell has many chloroplasts located through out the cell.
Cells are often solitary.
Distribution:
Rhizosolenia is eurythermal (found in temperatures ranging from - 2 to 30 °C)
and euryhaline (found in salinity ranging from 1.5 – 3). It is considered to be a north
temperate species but has been seen throughout the world's oceans from tropical to
cold temperate waters.

8.
Diatoms/Dinoflaellets/Zooplanktons
COF/NAU/AEN 201/Bhautik Savaliya/2016-17 Page 8
8. Genus:Skeletonema
Classification:
 Kingdom- Chromista
 Phylum -Bacillariophyta
 Subphylum- Bacillariophytina
 Class -Mediophyceae
 Subclass- Thalassiosirophycidae
 Order -Thalassiosirales
 Family -Skeletonemataceae
 Genus -Skeletonema
Description
Cells are short and cylindrical, usually connected in long, straight or slightly undulate
chains by a marginal ring of spines (strutted processes). The valve face is convex to flat.
Spines interlock midway between adjacent cells, visible as a dotted ring; spine lengths
are variable. There are two chloroplasts per cell and the nucleus is located centrally.
Distribution:-
Cosmopolitan in coastal except polar seas

9.
Diatoms/Dinoflaellets/Zooplanktons
COF/NAU/AEN 201/Bhautik Savaliya/2016-17 Page 9
9. Genus: Stephanopyxis
Classification:
 Empir -Eukaryota
 Kingdom- Chromista
 Phylum-Bacillariophyta
 Subphylum-Coscinodiscophytina
 Class -Coscinodiscophyceae
 Subclass- Archaegladiopsophycidae
 Orde -Stephanopyxales
 Family -Stephanopyxidaceae
 Genus -Stephanopyxis
Description: Cells are pill-shaped, from roughly cylindrical to almost spherical, and are
usually connected in straight chains. The valve surface is covered in coarse hexagonal
areolae that are all similar in size. No intercalary bands are present. Spines are also
slightly widened at the point of connection. Chloroplasts are numerous and discoid.
Cells are yellow-brown in colour.
Distribution:
Geographic: Temperate and subtropical species
Seasonal:

10.
Diatoms/Dinoflaellets/Zooplanktons
COF/NAU/AEN 201/Bhautik Savaliya/2016-17 Page 10
More abundant in late spring or early summer in Northern European waters often forms
spring blooms and occasionally present in the summer around the UK .
10. Genus:Thalassionema
Classification:
 Empire -Eukaryota
 Kingdom- Chromista
 Phylum -Bacillariophyta
 Subphylum- Bacillariophytina
 Class -Bacillariophyceae
 Subclass- Fragilariophycidae
 Order -Thalassionematales
 Family -Thalassionemataceae
 Genus -Thalassionema
Description: Cells are usually in star-shaped or zigzagged chains connected by
mucilage pads on the ends of valves. Cells are rectangular in girdle view, with valve
ends that are similar in shape and width, and are narrowly elliptical in valve view.
Chloroplasts are small and numerous. Cells are yellow brown in colour.

11.
Diatoms/Dinoflaellets/Zooplanktons
COF/NAU/AEN 201/Bhautik Savaliya/2016-17 Page 11
11. Genus: Thalassiosira
Classification:
 Empire- Eukaryota
 Kingdom- Chromista
 Phylum -Bacillariophyta
 Subphylum- Bacillariophytina
 Class -Mediophyceae
 Subclass- Thalassiosirophycidae
 Order -Thalassiosirales
 Family -Thalassiosiraceae
 Genus -Thalassiosira
Description: Thalassiosira is a short cylinder in shape and varies in size from 4 to 32
µm in diameter. It tends to be larger in winter, typically 15 µm in diameter, but smaller
in summer (5 µm). It occurs both singly and in groups and may be embedded in a
gelatinous matrix. There is a silicaceous cell wall with two frustules or valves, a larger
epivalve and a smaller hypovalve. The face of the valves varies in shape but is
basically irregular rings with one labiate and two or more central processes.
Distribution and habitat:
The native range of Thalassiosirais unclear, but it is found in marine, brackish and
freshwater environments. It seems to grow best at higher salinities and occurs in
coastal waters in the Atlantic and Pacific Oceans and in rivers and lakes in Europe,

12.
Diatoms/Dinoflaellets/Zooplanktons
COF/NAU/AEN 201/Bhautik Savaliya/2016-17 Page 12
Asia, South and North America, including the Great Lakes, where it was thought to
have been introduced in ballast water.
12.Genus: Thalassiothrix
Classification:
 Empire- Eukaryota
 Kingdom- Chromista
 Phylum -Bacillariophyta
 Subphylum- Bacillariophytina
 Class -Bacillariophyceae
 Subclass- Fragilariophycidae
 Order -Thalassionematales
 Family -Thalassionemataceae
 Genus -Thalassiothrix
Description: Very long cells that can be solitary or form radiating colonies. Cells can
be straight, slightly curved, or sigmoid, and are usually strongly twisted. Valves
inflated at the center and apices, and marginal spines are present.
Distribution:
Wide spread throughout the world's oceans.

13.
Diatoms/Dinoflaellets/Zooplanktons
COF/NAU/AEN 201/Bhautik Savaliya/2016-17 Page 13
13. Genus: Chaetoceros
Classification:
 Empire- Eukaryota
 Kingdom- Chromista
 Phylum -Bacillariophyta
 Subphylum- Bacillariophytina
 Class -Mediophyceae
 Subclass- Chaetocerotophycidae
 Order -Chaetocerotales
 Family -Chaetocerotaceae
 Genus -Chaetoceros
Description: Cells are roughly rectangular in girdle view and connected in spiraling
chains. Valves are flat or slightly convex (although the spines make it seem
concave). Apertures are narrowly oval and sometimes slightly constricted in the
middle. Spines are thin and arise just within the margins, crossing just outside their
base and extending outwards from the spiral. One chloroplast per cell. Cells are
yellow-brown in colour.
Distribution:
Present from spring to fall around Northern European seas, with highest abundance in
the spring. An important contributor to spring blooms in NE Atlantic and in Arctic
waters

14.
Diatoms/Dinoflaellets/Zooplanktons
COF/NAU/AEN 201/Bhautik Savaliya/2016-17 Page 14
14. Genus: Bacteriastrum
Classification:
 Empire- Eukaryota
 Kingdom- Chromista
 Phylum -Bacillariophyta
 Subphylum- Bacillariophytina
 Class -Mediophyceae
 Subclass- Chaetocerotophycidae
 Order -Chaetocerotales
 Family-Chaetocerotaceae
 Genus -Bacteriastrum
Description: Bacteriastrum is a widely distributed marine, planktonic genus. This
genus is often associated with Chaetoceros but differs in radial symmetry and
fenestration of setae. The colonies tend to lie in girdle view, and the cells are separated
by the curvature of the basal part of the setae, leaving a small gap between the cells. The
cells are cylindrical and linked to form filaments. Each cell has several long, radiating
setae which may be simple or bifurcate (branched), the setae from adjacent cells are
fused. The plastids are discoid.
Distribution:-

15.
Diatoms/Dinoflaellets/Zooplanktons
COF/NAU/AEN 201/Bhautik Savaliya/2016-17 Page 15
Diversity, occurrence and habitats of the diatom genus Bacteriastrum (Bacillariophyta)
in the northern Adriatic Sea, with the description of Bacteriastrum. Bacteriastrum is an
important component of the pelagic diatom assemblage.
15. Genus: Asteromphalus
Classification:
 Empire- Eukaryota
 Kingdom- Chromista
 Phylum -Bacillariophyta
 Subphylum- Coscinodiscophytina
 Class -Coscinodiscophyceae
 Subclass- Coscinodiscophycidae
 Order -Asterolamprales
 Family -Asterolampraceae
 Genus -Asteromphalus
Looks like: Sea biscuit, sand dollar
Description: Centric diatom, valve outline broadly oval or circular, or oblong. One
hyaline ray narrower than the others (for A. hookeri). Narrow ray is either rectangular
or bell shaped, and sectors are wedge shaped and curve towards valve center.
Cell size: Diameter 42-175um
Distribution: Warm, temperate and southern cold water regions.

16.
Diatoms/Dinoflaellets/Zooplanktons
COF/NAU/AEN 201/Bhautik Savaliya/2016-17 Page 16
16. Genus: Asterionellopsis
Classification:
 Empire -Eukaryota
 Kingdom- Chromista
 Phylum -Bacillariophyta
 Subphylum- Bacillariophytina
 Class -Bacillariophyceae
 Subclass- Urneidophycidae
 Order -Rhaphoneidales
 Family-Rhaphoneidaceae
 Genus –Asterionellopsis
Description: Pennate diatom. Cells joined by valve faces into star-shaped or spiralling
chains. Two chloroplasts per cell.
Cell Size: Length (apical axis)= 30-150um
Distribution: Neritic, cosmopolitan in cold to temperate coastal waters.

17.
Diatoms/Dinoflaellets/Zooplanktons
COF/NAU/AEN 201/Bhautik Savaliya/2016-17 Page 17
Dinoflagellates
1. Genus: Ceratium - Dinoflagellate
Monterey Bay species: C. furca, C. lineatum, C. pentagonum, C. fusus, C. platycorne
Order: Gonyaulacales
Family: Ceratiaceae
Description: Large, diverse genus. Armored, gonyaulacoid body, two to four hollow
horns. Horns open or closed. Chloroplasts present.
Cell Size: Width = 5-50um, Length =70-500um
Distribution: Cosmopolitan, neritic, cold and warm waters. C. furca is very common
in Monterey Bay and often forms dense blooms.

18.
Diatoms/Dinoflaellets/Zooplanktons
COF/NAU/AEN 201/Bhautik Savaliya/2016-17 Page 18
1. Genus: Dinophysis – Dinoflagellate
Classification:
 Empire- Eukaryota
 Kingdom- Chromista
 Phylum -Miozoa
 Superclass- Dinoflagellata
 Class -Dinophyceae
 Order -Dinophysiales
 Family -Dinophysaceae
 Genus -Dinophysis
Dinophysis acuminata, D. fortii, D. tripos, D. rotundata, D. caudata
Description: Armored, laterally flattened, oval-shaped cells with small flat or rounded
epitheca. Hypotheca is usually aTbout ¾ of the cell length. Wide girdle bounded by
lists. Chloroplasts present or absent.
Cell size: Width = 30-60um, Length = 22-105um
Distribution: Widespread throughout the world oceans - can be oceanic, planktonic,
benthic, or neritic.

19.
Diatoms/Dinoflaellets/Zooplanktons
COF/NAU/AEN 201/Bhautik Savaliya/2016-17 Page 19
Interesting facts: Some species produce okadaic acid and dinophysis toxins, which
cause diarrheic shellfish poisoning.
2. Genus: Gonyaulax- Dinoflagellate
Classification:
 Kingdom-Protoctista
 Phylum-Dinoflagellata
 Subphylum-Pyrrhophyta
 Class-Dinophyceae
 Order-Dinophysiales
 Family-Dinophysiaceae
 Genus -Dinophysis
Gonyaulax spinifera, G. polyedrum
Description: Armored, ovoid to fusiform cells with chloroplasts. Some species form
benthic cysts. Distinguished by descending cingulum up to 6x girdle width.
Cell size: Width = 25-136um
Distribution: Widespread throughout the world oceans.

20.
Diatoms/Dinoflaellets/Zooplanktons
COF/NAU/AEN 201/Bhautik Savaliya/2016-17 Page 20
Zooplankton
1. Acanthometronn sp.
Classification:
 Phylum- Protozoa
 Class -Acantharia
 Order-Arthracanthida
 Family -Acanthometridae
Description: It is entirely planktonic and it projects in all directions as exceedingly
thin and long straight sticky filaments, which have a more rigid axis for support. When
any little plant or animal comes nearby, two or more rays come together to grasp it and
between them bear it in a stream of protoplasm towards the central mass to be
digested. Apart from a siliceous and beautiful skeleton, Acanthometron also have a
perforated central capsule of a horny substance, which envelopes either a single very
large nucleus or a number of smaller ones.

21.
Diatoms/Dinoflaellets/Zooplanktons
COF/NAU/AEN 201/Bhautik Savaliya/2016-17 Page 21
2. Globigerina rubescens (Hofker)
Classification:
 Phylum -Protozoa
 Class -Granuloreticulosea
 Order -Foraminiferida
 Family –Globigerinidae
 Species-G. rubescens
Description: Test consists of a number of small visible chambers and the test is
coarsely perforated.

22.
Diatoms/Dinoflaellets/Zooplanktons
COF/NAU/AEN 201/Bhautik Savaliya/2016-17 Page 22
3. Favella philippinensis
Classification:
 Phylum - Protozoa
 Class -Ciliata
 Order-Tintinnida
 Species-Favella philippinensis
Description: This species is characterised by the presence of a fairly long, clean and
campanulated lorica. The posterior end of the lorica ends with a short pedicel-like
structure called the aboral horn, which is provided with 2 small ears or wing-like
structures, one on either side of the aboral horn. It differs from F. brevis in the absence
of annuli. This species is also known for its polymorphism as its individuals possess an
aboral horn that varies in size and structure.
Size: Length 192-312 µm and oral diameter 114 - 144 µrn.

23.
Diatoms/Dinoflaellets/Zooplanktons
COF/NAU/AEN 201/Bhautik Savaliya/2016-17 Page 23
4. Peniliaavirostris
Classification:
 Phylum -Arthropoda
 Class -Crustacea
 Sub class -Branchiopoda
 Order -Diplostraca
 Family –Sididae
 Species - Penilia
Description: Carapace forming a bivalved shell. The carapace does not cover the head
and it has beaklike rostrum.

24.
Diatoms/Dinoflaellets/Zooplanktons
COF/NAU/AEN 201/Bhautik Savaliya/2016-17 Page 24
5. Sagitta sp.
Classification:
 Minor Phylum - Chaetognatha
 Order - Aphragmophora
 Family – Sagittidae
 Species – Sagitt bipunctatas
Description: It is a small chaetognath (arrow worm) with a body comparatively
slender, rigid and transparent. The body could be divisible into head, trunk and tail.
There are two pairs of lateral fins in the trunk region besides a single tail fin. The
posterior fin is slightly larger than the anterior fins and completely rayed. The head
bears sickle shaped spines around the mouth, which together form ‘seizing jaw’. The
sides of the body are covered with numerous tufts of sensitive papillae. It is a
hermaphroditic form, mainly distributed in tropical seas and is considered to be an
indicator species.

25.
Diatoms/Dinoflaellets/Zooplanktons
COF/NAU/AEN 201/Bhautik Savaliya/2016-17 Page 25
6. Lucifer hanseni
Classification:
 Phylum - Arthropoda
 Class -Crustacea
 Order-Decapoda
 Sub order –Dendrobranchiata
 Species- Lucifer hanseni
Description: The luciferids are holoplanktonic and readily distinguished by the
extreme elongation of the cephalothorax, which shifts the oral appendages far away
from the antennae. The body of the adult reaches 1 cm in length and the head alone is
0.25 cm long. The animal is laterally compressed. The 5th (also at times the 4th)
pereiopod is absent or vestigial. Gills and luminescent organs are absent. However,
luminescent cells apparently are present in the telson. The male is characterised by a
petasma and spermatophore. The inshore lucifers are known to have shorter eye-stalks
than their offshore relatives.

26.
Diatoms/Dinoflaellets/Zooplanktons
COF/NAU/AEN 201/Bhautik Savaliya/2016-17 Page 26
7. Balanus nauplius
Classification:
 Phylum - Arthropoda
 Class - Crustacea
 Subclass –Cirripedia
 Species-Balanus nauplius
Description: Triangular body and the later naupliar stages have a pair of posterior
spines. The tip of the rostrum is truncated. 1st stage is about 0.3mm and the V stage
0.9mm.

27.
Diatoms/Dinoflaellets/Zooplanktons
COF/NAU/AEN 201/Bhautik Savaliya/2016-17 Page 27
8. Shrimp Zoea
Classification:
 Phylum -Arthropoda
 Class -Crustacea
 Order -Mysidacea
 Family –Penaeidae
 Species-Penaeus spp. protozoea
Description: The naupliar stage metamorphosis into a protozoea stage after about six
moults. It is a slender shaped larva, which is unlikely to be confused with anything
else except forms like Acetesprotozoea. It has broad oral carapace covering upto
second thorax segment. Also stalked eyes are present which occur as thickenings of
the anterolateral portion of carapace. Then, there is a small Nauplius eye. The
abdominal segments (except the first one) bear appendages. Telson forked and each
fork is short and round posteriorly and is having 7 setae of which the 4th from the
outside is the largest.

28.
Diatoms/Dinoflaellets/Zooplanktons
COF/NAU/AEN 201/Bhautik Savaliya/2016-17 Page 28
9. Crab Zoea
Classification:
 Phylum -Arthropoda
 Class -Crustacea
 Order -Decapoda
 Suborder -Brachyura
Description: The single dorsal and rostral spine can be greatly elongated or very short.
A pair of lateral spines is present, one pointed downwards and other pointed forwards
and upwards. The end of the spines flattened like spear head.

29.
Diatoms/Dinoflaellets/Zooplanktons
COF/NAU/AEN 201/Bhautik Savaliya/2016-17 Page 29
10. Megalopa Larva
Classification:
 Phylum - Arthropoda
 Class - Crustacea
 Order -Decapoda
 Suborder -Brachyura
Description: This crab ‐ larval stage appears in a period of 20 days. While all the
appendages are well developed, the abdomen with 5 pairs of swimming pleopods is
held in an extended position. The carapace, unlike in zoea, is depressed. A rostral
spine long and slightly curved.

30.
Diatoms/Dinoflaellets/Zooplanktons
COF/NAU/AEN 201/Bhautik Savaliya/2016-17 Page 30
11. Trochopore larva
Classification:
 Phylum - Annelida & Mollusca
 Class -Polychaeta & Gastropoda
Description: Primitive polychaete worms and molluscs possestrochopore larva. The
larva of a polychaete is almost spherical and at its upper pole has a little tuft of long
cilia and sensory cells, the so ‐ called apical sense organs. The mouth, located
equatorially leads into a gut which passes via a little round stomach and a short
intestine to open at an anus at the lower pole. A main ciliated girdle (prototroch or
preoral band of cilia) runsaround the sphere just above the equator. The cilia help in
spinning these spheres like a top. This motion creates ciliary currents that draw minute
particles of food from nearby areas into the mouth.

31.
Diatoms/Dinoflaellets/Zooplanktons
COF/NAU/AEN 201/Bhautik Savaliya/2016-17 Page 31
12. Cyphonautes larva
Classification:
 Minor Phylum -Bryozoa
 Class -Gymnolaemata
 Order -Cheilastomata
Description: Thecyphonautes of Membranipora membranacea is identified by its
transparency and symmetrical shape. The posterior margin of the oral edge bears a
rounded protuberance. The length of the oral edge is 0.7mm. This triangular ‐ shaped
larva is enclosed within a small bivalve shell. The larva starts as a trochophore but
with the underside tucked upinside like a little bell. Then it becomes flattened
sideways and develops minute three ‐ corner shells on each side.

32.
Diatoms/Dinoflaellets/Zooplanktons
COF/NAU/AEN 201/Bhautik Savaliya/2016-17 Page 32
13. Bivalve veliger
Classification:
 Phylum -Mollusca
 Class -Bivalvia
Description: The shell of the larva is very small in size and the larva has a straight
hinge line. The umbo is massive and prominent and the shell is distinctly coloured.

33.
Diatoms/Dinoflaellets/Zooplanktons
COF/NAU/AEN 201/Bhautik Savaliya/2016-17 Page 33
14. Fish Eggs
Classification:
 Phylum -Chordata
 Class -Pisces
Description: Fish eggs are generally spherical in shape and contain yolk and oil
globules. The eggs are categorized as temporary plankton or meroplankton and they
are found to be abundant in shallow coastal waters during certain seasons.

34.
Diatoms/Dinoflaellets/Zooplanktons
COF/NAU/AEN 201/Bhautik Savaliya/2016-17 Page 34
15. Creseis acicula
Classification:
 Species-Creseis acicula
 Phylum - Mollusca
 Class -Gastropoda
 Subclass -Opisthobranchia
 Order -Thecostomata (shelled pteropods)
 Common name- Sea butterfly
 Species-Creseis acicula
Description: This is an advanced mollusc and a fast swimmer. It possesses a shell
which is straight and tapering and is made of calcium carbonate. The maximum length
of the shell may be a few centimetres. The front part of the body of these animals is
drawn out on either side into two symmetrical wing-like lobes and hence they are
popularly known as 'sea butterflies'. These lobes or parapodia are a modified foot and
form an important part of the feeding mechanism. They are ciliated and by the action
of the cilia, food particles such as diatom and other small organisms are sent to the
mouth in a steady stream. Further, by the slow flapping movements of these lobes, the
animal progresses through water.