1. By:By:
Christian Jay Rayon NobChristian Jay Rayon Nob
BS-Marine BiologyBS-Marine Biology
Mindanao Sate University-Naawan CampusMindanao Sate University-Naawan Campus
COPEPOD
2. History of Systematic of Copepod
Copepods are a group of small
crustaceans found in the sea and nearly
every freshwater habitat. Cope is Greek
meaning an “oar” or “paddle;” pod is
Greek for “foot.” Some species are
planktonic (drifting in sea waters), some
are benthic (living on the ocean floor),
and some continental species may live in
limno-terrestrial habitats and other wet
terrestrial places.
3. Copepods have antennae and appendages that are
used like paddles for movement. Some species swim in a
jerky fashion, while others move more smoothly.
Interestingly, several planktonic species live at
different depth in the water column as they progress
through their life cycle.
Copepods have two swimming speeds. The first is
slow, steady, and accomplished using their mouthparts.
The second looks like a succession of jumps separated by
stillness. This jumpy form of swimming in accomplished by
the appendages on the thorax. Planktonic copepods have
been shown to collect and handle particles in a most
interesting way necessary because of their small size and
interaction with the water they live in. Tiny copepods (the
smallest look like specks of dust) live most everywhere in
the ocean in numbers too vast to count. They're a key link
in ocean food webs. They eat diatoms and
other phytoplankton and are eaten in turn by larger
drifters, larval fishes and filter feeders. Copepods may be
the most abundant single species of animal on Earth.
4. Physiology
Copepods have a variety of sensory
capabilities. The most noteworthy are
bristle-like setae that act as
mechanoreceptors responding to flow that
causes bending. An array of such sensors
allows detection of patterns of water flow
around the body caused by approaching
prey or predator, and the copepod can
distinguish between the two. The sensors
are highly specialized for sensitivity and
the nerves are even myelinated for fast
conduction.
5. LIFE CYCLE
During mating, the male copepod grips the female with his
first pair of antennae, which is sometimes modified for this
purpose. The male then produces an adhesive
package of sperm and transfers it to the female's genital
opening with his thoracic limbs. Eggs are sometimes laid
directly into the water, but many species enclose them
within a sac attached to the female's body until they hatch.
In some pond-dwelling species, the eggs have a tough shell
and can lie dormant for extended periods if the pond dries
up.
Eggs hatch into nauplius larvae, which consist of a head
with a small tail, but no thorax or true abdomen. The
nauplius moults five or six times, before emerging as a
"copepodid larva". This stage resembles the adult, but has
a simple, unsegmented abdomen and only three pairs of
thoracic limbs. After a further five moults, the copepod
takes on the adult form. The entire process from hatching
to adulthood can take anything from a week to a year,
depending on the species
7. Biodiversity of Copepod
Copepods are probably the most common
and abundant holoplanktonic organisms
worldwide, occurring in all oceans, seas,
estuaries, rivers and lakes. Some 13,000
species of copepods are known, and 2,800 of
them live in freshwaters. Copepods have
colonized virtually every habitat from 10,000
meters down in the deep sea to lakes 5,000
meters up in the Himalayas, and every
temperature regime from subzero polar waters
to hot springs.
8. These minute arthropods inhabit all
types of marine sediments - from sand
to fine mud and ooze - and can even be
found on land in damp moss and in
subterranean habitats, such as caves
and groundwater.
9. Marine Habitats
Although copepods can be found almost everywhere
where water is available most of the more than 12.000
known species live in the sea. As they are the biggest
biomass in the oceans some call them the insects of the
sea. They roam the free water, burrow through the
sediment at the bottom of the seas, are found on tidal
flats and in the deep sea trenches. At least one third of
all species live as associates, commensals or parasites
on invertebrates and fishes. One of the hotspots of
species diversity are the tropical coral reefs in the
Indopacific. Some coral species are hosts to up to 8
copepod species. Like the tidal flats the mangroves teem
with copepod life.
10. Freshwater Habitats
Species of the Calanoida, Cyclopoida and
Harpacticoida have successfully colonised all
kinds of freshwater habitats from little creeks to
glacier lakes high up in the Himalaya. Although
the species diversity in freshwater is not as
high as in the sea copepod abundance may
sometimes be great enough to stain the water.
Even in the groundwater a specialised copepod
fauna has evolved. Some copepod species can
be found in the leaf fall of wet forests or in a
wet compost heap, sometimes in rather high
densities. Others live in peat moss or even in
the phytothelmata (little pools formed in the
leave axils of plants) of bromeliads and other
plants.
11. Based on UPMC Sorbonne University,EMBRC (European Marine Biological Resource Centre), CNRS.
GEOGRAPHICAL DISTRIBUTION
2546 species of pelagic Copepods have been
inventoried to date (2011/2012) in all the world's
oceans and seas, with Calanoida predominating
(80.6 %), the other orders with 471 species (19.4 %).
Among the 25 arbitrarily defined geographic zones, the
number of forms inventoried is maximal for the Indian
Ocean and minimal for the Arctic Ocean.
12. 3- (271 named forms + 5 cited as sp.) in the Zone Sub-Antarctic (276 sp.) 4- (290 named forms
+ 6 cited as sp.) in the Zone Antarctic .(296 sp.) 5- (447 named forms + 6 cited as sp.) in the
Zone South Africa (E & W), Namibia (453 sp.); 6- (339 named forms + 1 cited as sp.) in the
Zone Gulf of Guinea (sensu lato): Angola-Liberia (340 sp.); 7- (701 named forms + 10 cited
as sp.) in the Zone Venezuela, Caribbean Sea, Gulf of Mexico, Caribbean, Florida, Sargasso
Sea (711 sp.); 8- (725 named forms + 14 cited as sp.) in the Zone Cape Verde Is., Canary Is.,
Madeira Is., Azores, Bay of Biscay, Ibero-Moroccan Bay ( 739 sp.); 9- (374 named forms +
3 cited as sp.) in the Zone Ireland, English Channel, Faroe, Norway, North Sea, Baltic Sea .
(377 sp.); 10- Southern Iceland, southern Greenland (E & W), Strait of Davis, Labrador
Sea (205); 11- (255 named forms + 2 cited as sp.) in the Zone Cape Cod, Nova Scotia, Island
of Newfoundland (257 sp.); 12- (328 named forms + 1 cited as sp.) in the Zone Central
South-Atlantic (Tristan da Cunha-Trinidad-St Helena-N Ascension) (329 sp.); 13- (377
named forms + 2 cited as sp.) in the Zone Brazil-Argentina (379 sp.); 14- (552 named forms +
1 cited as sp.) in the Zone Mediterranean Sea, Black Sea (553 sp.); 15- Red Sea (259 sp.);
16- (936 named forms + 28 cited as sp.) in the Zone Indian Ocean (964 sp.) 17- (624 named
forms + 4 cited as sp.) in the Zone Gulf of Thailand, Malaysia-Indonesia-Philippines (628
sp.); 18- (504 named forms + 14 cited as sp.) in the Zone Australia (E), Great Barrier Reef,
Tasman Sea, New Zealand, New Caledonia (518 sp.); 19- (525 named forms + 8 cited as sp.)
in the Zone Central Tropical Pacific (533 sp.); 20- (477 named forms + 3 cited as sp.) in the
Zone Eastern Tropical Pacific (Central America, Galapagos, Northern Peru) (480 sp.); 21-
(602 named forms + 4 cited as sp.) in the Zone China Seas, Vietnam (606 sp.); 22- (669 named
forms + 8 cited as sp.) in the Zone Japan Sea, Japan) (677 sp.); 23- (351 named forms + 2
cited as sp.) in the Zone North West Pacific (Sea of Okhotsk-Kuril Islands-Kamtchatka-Sea
of Bering) (353 sp.); 24- (290 named forms + 1 cited as sp.) in the Zone North East Pacific
(Gulf of Alaska, "P" station, British Columbia) (291 sp.); 25- (439 named forms + 1 cited as
sp.) in the Zone California-Gulf of California (440 sp.); 26- (433 named forms + 1 cited as sp.)
in the Zone Chile (sensu lato)(434 sp.) ; 27- (157 named forms + 7 cited as sp.) in the
Zone Arctic Ocean (164 sp.)
•(624 named forms + 4 cited as sp.) in the Zone Gulf of
Thailand, Malaysia-Indonesia-Philippines (628 sp.)
•The geographical distribution of species is linked in some cases
to the historical evolution of the continents, and in many others
to general surface currents. Deep-water currents, which are
poorly documented, may perhaps explain the erratic presence
of some forms.
13. Terms in the Systematics of Copepod
Body Length - The length from the anterior margin of the head
region to the posterior margin of the caudal rami excluding the caudal
setae.
Body Regions – Useful to refer to three regions of the body of the
copepod visibility distinguishable from one-another.
Cephalosome – The anterior unsegmented region of the body that
includes not only the head but also, at the least, the segment of the
maxillipeds.
Metasome – the segmented region of the body immediately posterior
to the cephalosome and anterior to the urosome.
Urosome – the posteriormost region of the body of the copepod,
usually narrower than the rest of the body and marked off from the
metasome by a distinct articulation in virtue of which the urosome
can be freely moved about like a tail.
Caudal Rami – A pair of laminar structures at the posterior end of
the anal segment, movably articulated with the latter and each
provided typically with six setae.
Geniculation – Modification of the first antennae for prehension or
grasping, through the formation of an elbow or hinge.
14. Endopods – the inner or medial branch of a two-
branced crustacean leg or appendage
Pereiopods – walking legs (swimming legs of
copepods); located under the cephalothorax or
metasome of crustaceans
Uniramous – in arthropods, an unbranched
appendage. In crustaceans the exopodite is often
lacking in walking legs.
Biramous – in crustacea it describes the
condition in which appendages are divided into
two segmented branches: exopodite (external
branch of the appendages of Crustacea) and
endopodite ( the inner or medial branch of a two-
branched crustacean leg or appendage), these
branches arise from a basal segment called the
basipodite (basal joint of the legs of crustaceans).
15. Appendages – a limb or other process
extending from the body, usually
articulated (having a joint or joints)
Abdomen – posterior section of the
body, behind the thorax or
cephalothorax
Thorax – the portion of the body
between the head and the abdomen
16. The consensus cladogram based on morphology and
small subunit ribosomal DNA sequence data is superimposed
on the geological column and shows the known body fossil
record of copepods (red lines), as well as the predicted origin
of the group (blue lines).
Cladogram
17. Evaluation:
The phylogenetic relationships of copepods have been debated in
the last decades. Some authors proposed evolutionary schemes
on account of the ecological radiation of copepods (Boxshall, 1986;
Ho, 1994) , other authors pointed out cladistic approaches.
Particularly Huys & Boxshall (1991). Calanoids, cyclopoids
and harpacticoids show a remarkable ecological interest, since
most species of these orders generally form the first link of the
aquatic food chains, from the microscopic phytoplanktonic algae up
to the fishes and mammalians. Recent researches, including those
carried out by the Dipartimento di Scienze Ambientali of the
University of L'Aquila (Italy), are pointing out an analogous
importance for cyclopoid and harpacticoid species inhabiting both
surface and underground fresh waters, and particularly the
sediments between the superficial hyporheic zone and the rivers
bottom, an interesting transitional system or ecotone between
epigean and stygal waters. As a matter of fact, the contiguity with
surface waters and the regular occurence of epigean elements in
the hyporheic habitats let now the hydrobiologists to consider that
a good estimation of rivers meiobenthic conditions must pass
through a careful knowledge of the relative groundwater
communities. In this last regard, an increasing number of
harpacticoid and cyclopoid species are actually revealing their
noteworthy importance as "pollution markers" in the
environmental control of hyporheic systems and other aquatic
habitats, such as lakes, springs, rivers and superficial ground
(phreatic) waters.
19. Copepods are usually very small and measure 0.019 to 0.78
inches (0.5 to 20 millimeters) in length. A few free-living species,
those that are not parasites, reach 0.7 inches (18 millimeters). The
copepod body consists of a head, a middle section called a thorax,
and the terminal section called the abdomen. The abdomen consists of
four or five discrete segments, depending on the species. The thorax
contains six segments. The unsegmented head is integrally united
with the first segment of the thorax.The copepod head has a pair of
segmented antennules (little antennae). The segments at the end of
each antennule have bristle-like structures called setae and thin-
walled hairs called aesthetascs. The aethetascs of the male copepod
have receptors that can sense chemical substances emitted by female
copepods. The male has longer antennules which develop a joint that
enables it to grasp the female during copulation. Some copepods have
only one eye. The copepod’s mouthparts are complex and vary from
species to species. Sometimes the mouthparts of the male and the
female differ. They possess three pairs of mouth parts. Two pairs are
called maxillae and the other is a pair of mandibles. The setae of the
antennae assist in directing food to the mouth, and a pair of
maxillipeds on the first thoracic segment also assist in feeding. Each
segments of the copepod thorax has a pair of appendages, but the
abdomen has none. The last segment of the abdomen terminates in a
sort of tail called a “caudal rami.
20. Dichotomous Key
Second antennae and mouth parts present; developmental
stages usually free swimming; adults free swimming or
Ectoparasitic (Parasites that live on the surface of the host )
only……………………………………………………………………
Second antennae and mouth parts absent in the adult
which is free swimming; developmental stages parasitic
………………………………………………………………………….MONSTRILLOIDA
Urossome includes not only the genital and abdominal
segments but one further segment bearing the 5th
pair of
legs; first antennae of the male, if geniculate, geniculate on
both sides…………………………………………………………………….
Urosome includes the genital and abdominal segments only;
first antennae of the male, if geniculate, geniculate on one
side only, commonly on right
side………………………………………………….. CALANOIDA
21. Body usually cylindrical, the metasome passing into the
urosome without abrupt change in width; basal segment
of the fifth legs usually showing an inner expansion;
males distinguished from the females in all cases by the
geniculation of the first antennae ; egg sacs usually
unpaired, carried underneath………………HARPACTICOIDA
Body usually depressed with the metasome much wider
urosome; basal segment of the fifth legs without an
inner expansion; geniculation of the first antennae of the
male is usual but not invariable; eggsacs paired, carried
laterally of subdorsally……………………………………
CYCLOPOIDA
22. Urosome 4-segmented ; 5th
legs symmetrical, fully setose
(covered with setae or bristles )
…………………………………………………………FEMALES
Urosome 5-segmented ; 5th
legs unlike on the two sides;
the left leg being usually longer through the greater
elongation of the two proximal exopodite segments, the
terminal segment being rather short…………………….MALES
24. Order Calanoida
include around 40 families with about 1800 species of
both marine and freshwater copepods. Calanoid
copepods are dominant in the plankton in many parts of
the world's oceans, making up 55%–95% of plankton
samples. They are therefore important in many food
webs, taking in energy from phytoplankton and algae
and 'repackaging' it for consumption by higher
trophic level predators. Many commercial fishes are
dependent on calanoid copepods for diet in either their
larval or adult forms. Baleen whales such as
bowhead whales, sei whales, right whales and
fin whales eat calanoid copepods.
25. Calanoids can be distinguished from other planktonic copepods byCalanoids can be distinguished from other planktonic copepods by
having firsthaving first antennaeantennae at least half the length of the body andat least half the length of the body and
biramous second antennae. Their key defining feature anatomically,biramous second antennae. Their key defining feature anatomically,
however, is the presence of a joint between the fifth and sixth bodyhowever, is the presence of a joint between the fifth and sixth body
segments. The largest specimens reach 18 millimetres (0.71 in)segments. The largest specimens reach 18 millimetres (0.71 in)
long, but most are 0.5–2.0 mm (0.02–0.08 in) longlong, but most are 0.5–2.0 mm (0.02–0.08 in) long
26. Order Cyclopoida
Like many other copepods, members
of Cyclopoida are small, planktonic
animals living both in the sea and in
freshwater habitats. They are capable
of rapid movement. Their
larval developmentis metamorphic,
and the embryos are carried in paired
or single sacs attached to first
abdominal somite.
Cyclopoids are distinguished from
other copepods by having first
antennae shorter than the length of
the head and thorax, and uniramous
second antennae. The main joint lies
between the fourth and fifth segments
of the body
27. Order Gelyelloida
Gelyella
a genus of freshwater copepods
which are "surrounded by
mystery".They live in groundwater
in karstic areas of southernFrance
and western Switzerland.
Gelyella shows some
paedomorphosis, in which animals
reach sexual maturity while still
partly resembling juveniles. The
adults are 300–400 micrometres
(0.012–0.016 in) long with a
nearly cylindrical body that tapers
towards the rear. There are
eleven body segments, the last of
which is the length of the previous
two segments combined.
28. Order Harpacticoida
This order comprises 463 genera and about
3,000 species; its members are benthic
copepods found throughout the world in the
marine environment (most families) and in
fresh water (essentially the Ameiridae,
Parastenocarididae and the Canthocamptidae).
A few of them are planktonic or live in
association with other organisms. Harpacticoida
represents the second-largest meiofaunal group
in marine sediment milieu, after nematodes. In
Arctic and Antarctic seas, Harpacticoida are
common inhabitants of sea ice.
29. Harpacticoids are distinguished from other copepods by the presence ofHarpacticoids are distinguished from other copepods by the presence of
only a very short pair of firstonly a very short pair of first antennaeantennae. The second pair of antennae are. The second pair of antennae are
biramous, and the major joint within the body is located between the fourthbiramous, and the major joint within the body is located between the fourth
and fifth body segments. They typically have a wideand fifth body segments. They typically have a wide abdomenabdomen, and often, and often
have a somewhat worm-like body. Sixty-seven families are currentlyhave a somewhat worm-like body. Sixty-seven families are currently
recognised in the Harpacticoidarecognised in the Harpacticoida
31. Order Monstrilloida
is an order of copepods with a
cosmopolitan distribution in the world's
oceans. The order contains a single
family,Monstrillidae; The taxonomy of
the family is undergoing a period of
revision. The order is poorly known,
biologically and ecologically, although
the life cycle is known to differ from that
of all other copepods. Thelarvae are
parasites of benthic polychaetes and
gastropods, while the adults are
planktonic and incapable of feeding,
functioning solely to reproduce. but a
rudimentary or absent fifth pair. Adults
have no oral appendages, and the mouth
leads only to a short, blind pharynx.
Females carry a long pair of spines to
which the eggs are attached, while
males have a "genital protuberance,
which is provided with lappets"; in both
sexes, the genitalia are very different
from those of all other copepods.
32. Order Platycopioida
Members of the Platycopiidae
have a primitive form, thought to
be similar to the
most recent common ancestor of
all copepods. Few
synapormorphies have been
found to unite the family, but
they include the presence of a
second dorsal seta (hair) on
particular segments of the
legs. They share with
calanoid copepods the
possession of Von Vaupel Klein's
organ, a sensory organ near the
base of the first swimming leg.
33. Order Poecilostomatoida
The classification of these copepods has
been established on the basis of the
structure of the mouth. In
poecilostomatoids the mouth is
represented by a transverse slit,
partially covered by the overhanging
labrum which resembles an upper lip.
Although there is variability in the form
of the mandible among
poecilostomatoids, it can be generalized
as being falcate (sickle-shaped). The
antennules are frequently reduced in
size and the antennae modified to
terminate in small hooks or claws that
are used in attachment to host
organisms.
34. Most poecilostomatoid copepods are ectoparasites of
saltwater fish or invertebrates (including among the latter
mollusks andechinoderms). They usually attach to the
external surface of the host, in the throat-mouth cavity,
or the gills. One family of poecilostomatoid copepods,
however, have evolved an endoparasitic mode of life and
live deep within their hosts' bodies rather than merely
attaching themselves to exterior and semi-exterior
surface tissue.
In addition to typical marine environments,
poecilostomatoid copepods may be found in such very
particular habitats as anchialine cavesand deep sea vents
(both hydrothermal vents and cold seeps). Here, many
primitive associated copepods belonging to the orders
Poecilostomatoida and Siphonostomatoida and have been
found. Representatives of one Poecilostomatoida family
have successfully made the transition
to freshwater habitats and host animals therein.
35. Order Siphonostomatoida
are copepods of the order of
the subclass Maxillopoda, inside
the subphylum Crustacea. There are 42
recognised families. They are
ectoparasites on the body surface of
marine fishes; not the parasitic
adaptations.The body shows a fushion
of the ancestral body somites: a large,
flat cephalothorax followed by one to
three free thoracic segments (prosome),
a large genital segment, and a smaller
unsegmented abdomen (urosome). The
principal appendages for prehension are
the second antennae and maxillipeds.
37. Order Calanoida
Family Specie Distinguishing
charactestics
Image
Acartiidae Small and slender; Single eye present.
Acartia
tranteri
Cigar-shaped body. Rounded edges
on prosome posteriorly. Naupliar eye
very prominent.Colour: transparent to
dark grey when alive.
Acartia
danae
Top of head is flat or slightly triangular.
Long, slender cigar-shaped body. Long,
spaced out setae on antennae. Fresh
specimens usually transparent, with
prominent eye-spot (red or
black).Metasome is pointed anteriorly in
dorsal view and bears a pair of sharp
points posteriorly.
Calanidae Body elongate-oval
shaped.Abdomen moderately
long.Long antennules.
38. Calanus
australis
Relatively large
species.Cephalosome is rounded
anteriorly.Inner margin of basipodite
(2nd segment) 1 of leg 5 is serrated
(toothed). No recurved spine on the
outer distal border of the
1st exopodite segment of leg
2.1st antenna exceeds the body
length by a few segments
Nannocalanus
minor
Bullet shaped.Readily recognized
from other Calanus species by the
small size.
Cephalosome is rounded
anteriorly.Head and 1st leg-bearing
segment of the metasome are fused.
Centropagidae Wide, rectangular shaped
bodies.Posterior corners
of prosome often quite pointed and
distinct.
Centropages
australiensis
Cephalosome is rounded anteriorly in
dorsal view and bears a pair of sharp
points posteriorly
39. Paracalanidae
Paracalanus
indicus
Cephalosome is rounded
anteriorly. Head
and pedigerous segment 1
are fused.5th pereiopods redu
ced and terminate in a spine
Delibus nudus
Very small, less than 1
mm;Cephalosome, pedigerous
somite 1, 4 and 5 fused; A1
extends to posterior border of
prosome;Rostrum bifurcate,
branches short and wide;Basis of P1
with inner edge setae;P2-4, outer
edge of exopod segments 2-3 are
smooth;Leg 5 is reduced only left
leg present, 2 segments in female,
5 in male
40. Order Cyclopoida
Oithonidae Small, long and slender
bodies.
Oithona atlantica Slender, tapered
body.Pointed rostrum
Oithona tenius
Detailed study of the
swimming legs is needed to
identify this species.
Cephalosome oval in
shape; cephalosome and uros
ome equal in length
Oncaea media
Readily identified by reddish colour
concentrated at anterior region of the
head and at the cuticle edges
of metasome, urosome and appendag
es. Colour can persist after several
years in formalin. Oval
shaped prosome. Nauplius eye present
41. Molecular Systematics of 34 Calanoid copepod species of
the Calanidae and Clausocalanidae
DNA sequences for a 639 bp region of mitochondrial
cytochrome oxidase I (mtCOI) were determined for 34
species of ten genera in two
familiesofcalanoidcopepods,including: Calanoides,Cosmoc
alanus, Meoscalanus, Nannocalanus, Neocalanus, and Un
dinula (familyCalanidae);andClausocalanus, Ctenocalanu
s, Drepanopus,and Pseudocalanus (family
Clausocalanidae). MtCOI gene sequences proved to be
diagnostic molecular systematic characters for accurate
identification and discrimination of the species. Levels of
mtCOI variation within species (range: 1–4%) were
significantly less than those between species (9–25%).
Higher levels of intraspecific variation (>2%) usually
resulted from comparisons between ecologically distinct
or geographically isolated populations. MtCOI sequence
variation resolved evolutionary relationships among
species of Clausocalanus, Neocalanus,
and Pseudocalanus, although there was evidence of
saturation at some variable sites.
42. Impact on Molecular Phylogenetics
Phylogenetic relationships among 11
copepod genera were reconstructed using a
660 bp region of nuclear small-subunit 18S
rRNA, a slowly evolving gene that showed
no variability within a species and differed
by <1–6% among the genera. The 18S
rRNA molecular phylogeny was consistent
with the accepted limits of the Calanidae
and Clausocalanidae and clearly resolved
relationships among genera within each
family.
43. Historical Content
With the universal aquatic occurrence of copepods, it is
not surprising that they were noted by the earliest
naturalists. Beginning two thousand years ago, many
scientists and "lovers of wisdom" with names still known
and respected throughout the world, like Aristotle, Pliny,
Rondelet, Redi, Leeuwenhoek, and Linnaeus, observed
copepods. Their careful records became a part of our
long written heritage, now numbering around 57,000
published works about copepods. The copepod world
took shape against the vast background of other
invertebrates. Our science saw many valuable
contributions in the century after the establishment of
Linnaeus's taxonomic system in 1758. Pioneer scientists
revealed the surprising reproduction and developmental
metamorphosis of copepods as well as their roles
throughout the natural world, particularly their
significance at the food-base of fisheries.
44. Honored names and landmark monographs from
this period include those of Otto Friderich Müller (1730-
1784, Denmark), Jean Baptiste Lamarck (1744-1829,
France), Georges Cuvier (1769-1832, France), Louis
Jurine (1751-1819, Switzerland), James Dwight Dana
(1813-1895, United States), and William Baird (1803-
1872, England). Since copepods did not have the
immediate impact or urgency of plants, insects, or larger
animals, they were studied only incidentally until the
middle of the 19th century. Even so, by that time, there
was a strong conceptual framework that recognized a
wide variety of copepod species and habitats; even the
remarkably "degenerate" parasitic copepods were no
longer thought to be worms or mollusks but were
revealed by their larval stages to be true crustaceans.
The name "copepod" (Greek for paddle-footed) was
introduced in 1830 by Henri Milne Edwards (1800-1885)
in France. The early taxonomic systems echo in our
classifications of today. The first prominent scientist to
devote most of his life to copepods was Carl Claus
(1835-1899),
45. Professor of Zoology at the University of Vienna. In
1863, Claus published the first book dealing only with
copepods. This helpful treatise summarized the
knowledge of free-living copepods of western Europe
and the Mediterranean Sea. Claus's other works included
classic studies of parasitic copepods, adding especially to
the useful papers of Henrik Krøyer (1799-1870) from
Denmark. After Darwin, in 1859, naturalists focused on
completing Nature's book by describing and indicating
the relationships of every species, a task that is far from
finished. This quest took biologists to the far corners of
the earth and to the greatest depths of the seas.
Extensive oceanographic expeditions in the last quarter
of the 19th century brought an unbelievable harvest of
copepods for an expanding and exclusive copepod
literature. The decade before and after 1900 was the
Golden Age of Copepodology, with the beautiful and
indispensable monographs of Wilhelm
46. Giesbrecht (1854-1913, Germany and Italy), Eugène Canu
(1864-1952, France), Otto Schmeil (1860-1943, Germany),
and Georg Ossian Sars (1837-1927, Norway). Also, toward the
end of the 19th century, the founder of ecology Karl Möbius
(1825-1908) and his followers began to measure the precise
impacts of copepods on their living and non-living
surroundings. More consideration was given to developmental,
geographical, and population characteristics of copepods. With
the 20th century, women scientists became equal partners in
the study of copepods. Among the first were Maria Dahl (1872-
1972) and Marie Lebour (1876-1971). These years saw
marvelous technical improvements in microscopes and
sampling, and a movement toward physiology and the
investigation of living copepods. Sheina Marshall (1896-1977),
Andrew Picken Orr (1898-1962), Aubrey Nicholls (1904-1986),
and Frederick Russell (1897-1984) laid the foundation of these
studies, a large part of copepodology's present efforts. The
lives of many of our heroes are overwhelming, and they stand
in the highest ranks of biology in every nation. Many who are
well known for other accomplishments made critical additions
to the body of copepod knowledge.
47. Their teachings and research became centers of
excellence, attracting students from far and wide. Their names
are linked forever with the variety, distribution, and behavior
of the freshwater, marine, free-living, and parasitic copepods
they described. Among these immortals are P. J. Van Beneden,
V. Brehm, A. Brian, K. Brodsky, C. van Douwe, C. O. Esterly,
G. Grice, R. Gurney, H. J. Hansen, W. A. Herdman, A. G.
Humes, Fr. Kiefer, W. Klie, H. Kunz, K. Lang, A. Markevich, C.
D. Marsh, H. Marukawa, T. Mori, J. Richard, M. Rose, V. Rylov,
T. & A. Scott, A. Steuer, O. Tanaka, C. B. Wilson, and many
others who have become our own. The working copepodologist
sees in these names essential publications kept close at hand,
milestones in a unique science. Copepodology continues
uninterrupted into the 21st century, looking now at copepods
in ecosystems of oceans, lakes, and rivers, from deep-sea
vents to groundwaters. Armed with new tools like electron
microscopes, remote sensing, molecular biology, and
computers, copepodologists explore genetics,
medical/morphological applications, mathematical modeling,
precision sampling, a wealth of new species from extreme
habitats, environmental pollution and over-harvesting,
introduced species, and many other consequences and
opportunities undreamed of by our predecessors.
48. Taxonomic Techniques for Copepod
1. Initial treatment of specimens
a. Narcotizing agents
Narcotizing agents can be useful to avoid flexion of the body and the antennae, and to aid
retention of egg sacs and gut contents during fixation. The agent is usually added slowly, drop
by drop.
b. Fixation
Fill sample bottles 3/4 full. Try to fix within 5 minutes after catch.
c. Staining for sorting
Staining samples before or during fixation helps visual separation of specimens from sediment or
detritus-filled samples.
d. Storage
Storage Media:
Within 7-10 days transfer specimens to ethanol or other long-term storage medium; do not
leave material in formalin, even buffered, for long periods. This is because specimens become
brittle and setae break off easily.
e. Recovery of dried specimens
49. 2. Microscopic examination
Copepod taxonomy is based mainly on external
morphology. Therefore one needs to see details of the
integument. It may be desirable to use a clearing
medium to reduce visual interference from internal
structures, and to stain the integument in order to
highlight spine patterns, pores, and other features.
Sequence of treatment:
Pre-treatment
Stains
Mediums, temporary or permanent
Dissection
Mounting on slides, temporary or permanent
Making a record of the specimen
50. 3. Procedure for examination and mounting
a. Manipulation and Dissection
b. Mounting
The choice of mounting medium
depends on the use to be made of the
mounted specimens, the type of
microscopy employed, and the need for
long-term preservation.
51. Case Study
MORPHOLOGICAL AND MOLECULAR
PHYLOGENETIC ANALYSIS OF
EVOLUTIONARY LINEAGES WITHIN
CLAUSOCALANUS (COPEPODA:
CALANOIDA)
ftp://www.cmarz.org/pub/cmarz/pdf/cmarz_refs/Bucklin_Fros
t_JCrustBiol_2009.pdf
52. ABSTRACT
Phylogenetic relationships among 13 species of Clausocalanus (Copepoda:
Calanoida) were examined based on morphological, quantitative
(morphometrical), and molecular characters. This study builds upon
monographic analysis by Frost and Fleminger (1968) and seeks to determine
whether three described species groups are monophyletic evolutionary lineages.
DNA sequences were determined for portions of three genes: mitochondrial
cytochrome oxidase I (mtCOI; 639 base-pairs), nuclear internal transcribed
spacer region (ITS-2; 203 base-pairs), and nuclear ribosomal gene (5.8S rRNA;
73 base-pairs). Phylogenetic analysis was carried out based on morphological,
molecular, and combined morphological and molecular data using maximum
parsimony, maximum likelihood, and Bayesian algorithms, with evaluation of
best-fit models of nucleotide evolution. Phylogenetic reconstructions based on
morphological characters provided strong support for species groups I and II;
group III was not well-resolved. Analysis of the concatenated sequences of the
three genes resulted in a tree resolving three of five group II species, with weak
support for two pairs of group I species; the remaining species were not clearly
resolved into groups. Although ITS-2 was statistically incongruent with the
other data sets, the combined analysis of morphological, quantitative, and
molecular data by maximum parsimony resolved all four group I species and
four of five group II species; group III was not well resolved. All molecular and
combined analyses consistently paired C. arcuicornis(group II) with C.
parapergens (group III). This study provides independent evidence that some
elements of Clausocalanus species groupings reflect evolutionary lineages.
Additional genes and longer sequences may help resolve remaining questions
about the evolutionary relationships among species of Clausocalanus.
53.
54. Discussion
Monographic revision of the calanoid copepod genus, Clausocalanus,
by Frost and Fleminger (1968) resulted in the description of 13
species in three species groups, which were hypothesized to
represent evolutionary lineages within the genus. In a previous
molecular systematic analysis of all 13 species of Clausocalanus by
Bucklin et al. (2003), patterns of DNA sequence variation for the
mitochondrial cytochrome oxidase I (mtCOI) gene supported the
revision of the genus by Frost and Fleminger (1968), with mtCOI
differences among all species typical of that of well established
calanoid copepod species (Bucklin et al., 2003).
In this study, Clausocalanus species groups were resolved
most clearly by phylogenetic reconstructions using only Frost
and Fleminger’s four group-defining morphological characters.
Phylogenetic reconstructions using either 10 morphological
characters or all 16 morphological and quantitative characters
had lower bootstrap values and did not resolve group III
species. These results indicate that useful taxonomic
characters may have quite different evolutionary histories, and
not all such characters will accurately reconstruct the
evolutionary history of a species group.
55. Molecular phylogenetic analyses using mtCOI, ITS-2, or the
concatenated gene sequences provided strong consistent support only
for an evolutionary lineage comprising three of five group II species
and another pairing of two sister taxa C. arcuicornis and C.
parapergens from groups II and III, respectively. Neither groups I nor
III were resolved using the molecular data, either treating genes
separately or as concatenated sequence.
Although there was evidence of incongruence among the
morphological, quantitative, and molecular data sets, phylogenetic
reconstruction based on all these characters in combination yielded a
tree that resolved all four group I species and four of five group II
species. Thus, despite the necessary use of the maximum parsimony
algorithm for the combined data set, the integrated and combined
analysis of independently-evolving morphological and molecular
characters resulted in better resolution and more accurate
reconstruction of phylogenetic relationships within this genus of
copepods.
56. When are combined analyses useful and when
not?
One approach to answering such questions is to
reconstruct the phylogenetic history of a sibling
species group using separate analysis of different
characters, including, e.g., morphological,
quantitative, and molecular traits, and to compare
and contrast the resultant evolutionary patterns.
The data sets should also be evaluated for
difference of their phylogenetic histories using
tests of congruence (Farris et al., 1995). Such
analysis can help identify appropriate characters
for the accurate reconstruction of the evolutionary
relationships of the group and valid combinations
of data sets.
57. Conclusion
Copepods are identified as key species in the marine pelagial,
not only in the capacity of being a link between primary
producers of fish but as predators on other consumers.
Moreover, copepods are the most species-rich and abundant
invertebrates recorded from deep-sea hydrothermal vents and
seeps. They are considered the most plentful multicellular
group on the earth, outnumbering even the insects, which
include more species, but fewer individuals. Particularly, the
copepods are the dominant forms of the marine plankton and
constitute the secondary producers in the marine
environments and a fundamental step in the trophodinamics of
the oceans. Only a few studies of their biology, functional
morphology, and evolution have been conducted.
The systematics of copepods has been subjected to numerous
revisions during the last decade and before. Calanoids,
cyclopoids and harpacticoids show a remarkable ecological
interest, since most species of these orders generally form the
first link of the aquatic food chains, from the microscopic
phytoplanktonic algae up to the fishes and mammalians.
