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Earthworm (Oithwoim?) Dissection
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Return to Mr. Lazaroff’s Biology         Earthworm        Crayfish         Frog        Final Lab Report
It costs me never a stab nor squirm
to tread by chance upon a worm.
“Aha, my little dear,” I say,
“Your clan will pay me back one
– from Thought for a Sunshiny
Dorothy Parker
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Virtual Earthworm Dissection
Image borrowed from the Virtual Dissection website above
By Day: Day 1    Day 2
By Topic/Region: External Anatomy    Internal Anatomy
Skeletal    Lymphatic    Integumentary
Muscular    Endocrine    Nervous
Respiratory    Excretory    Digestive
S  L  I  C    M  E  N    R     R  E  D
(SLIC  Woims  R  RED?)
NOTE: The Systems in Italics above have their functions taken up by
other systems.
You must create a series of labeled drawings that ilustrate the structures outlined below:
Safety Goggles 1.
Apron 2.
A pair of medium thickness rubber Kitchen gloves (with your name on each), as per the Class Rules 3.
A Ziploc-style bag (with your name on it) in which to keep your gloves, as per the Class Rules 4.
A PENCIL (keep this in your Ziploc-style bag aboce, due to the chemicals) 5.
An old small towel, as per the Class Rules 6.
OPTIONAL An old long-sleeve shirt (for use under our lab aprons), as per the Class Rules 7.Tool Tray with:
(a) Forceps (your second-most valuable tool)
(b) Pointed Scissors (use with care, or you might damage your specimen)
(c) Rounded Scissors (use with the rounded end down)
(d) Scalpal (to be used very sparingly)
(e) Blunt Probe (your most valuable tool)
(f) Pins (use only a few)
(g) Bone Cutters (used the least, and only on the frog)
Dissection Tray 9.
Plastic Dissection Tray Cover 10.
Masking Tape & Pen (for labeling the tray cover) 11.
Pencil & Paper (for making your diagrams) – NOTE: Pen will NOT be accepted! 12.
Have I forgotten something . . . Oh, yes . . . an EARTHWORM! 13.
Day 1
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External Anatomy
Place the specimen prone (ventral surface down, dorsal surface upon the
dissecting tray.  (To what phylum does it belong?  What is your evidence
for that?)
Note the difference in coloration.   Why is the dorsal surface of the skin
Find the anterior and posterior ends and the clittellum (the wider portion,
which is closer to the anterior surface).
Count the number of segments.  (How many are there in front of the
clittelum?  In the clitellum?  Behind the clitellum?)
Using the Dissecting Microscope, place the tray on the stage, and draw:
(a) the mouth (What do they eat?  What does the soft texture of the
say about their diet?)
(b) the anus (What type of digestive system does it have, One-Way, or
(c) the setae, which are the dark projections on each section (How many
setae are there on each section?  What purpose do the setae serve?)
(d) the sperm duct opening (Which segment is it on?)
(e) the oviduct opening (Which segment is it on?  Given the existence of
what type of creature is it?  Given the location of both, is the
likely to self-fertilize?  What type of fertilization does it practice,
internal or external?)
Wipe off the dissecting microscope stage with a slightly moist paper towel
(if necessary) and dry it thoroughly.
Cover your entire specimen with a wet (not just moist) paper towel. 8.
Using masking tape and a pen, write your name and your partner’s name on
one of the plastic specimen tray lids.
Place the lid snugly on the tray and place the trays neatly on the middle
table in the back of the room.
Rinse off the tools and dry them thoroughly before returning them to the
tool tray.
NOTE: This clean up technique will be the same for all dissection days
Image purchased by Mr. Lazaroff, by subscription, from    except the last day for each specimen, described below.
Day 2
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Internal Anatomy
Place the specimen prone (ventral surface down, dorsal surface up)on the dissecting tray. 1.
Using a scalpal, make a shallow medial incision only 1 cm long on the dorsal surface 1/3 of the way from the posterior
Given that scalpals cut downward, and scissors can be lifted to cut upwards, you will use scissors to cut all the way
toward the anterior end.  TAKE CARE NOT TO CUT INTO THE INTESTINE.   (What do earthworms eat?  Given that,
what color would you expect the contents of the intestine to be?)
Using dissection pins placed at a 45
angle from the tray, pin back the skin of the earthworm along the anterior third of
the specimen.  (To what body system does the skin belong?  Given the earthworm’s form of locomotion, what else are
you pinnning back, and to what body system do they belong?  Lastly, this system takes up the function of what other
NOTE: All subsequent diagrams need to use the dissecting microscope.
Identify and diagram the Nephridia (singular = Nephridium).  (What is their function?  What is the equivalent organ in
humans, and to what body system does it belong?  Is the fact that they are in pairs in the worm at all retained in our

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Identify and diagram the Pharynx & Esophagus.  (What is the one function of the two organs?  How is their function
similar in humans, and how is it different?)
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Identify and diagram the Gizzard & Crop.  (Which of the two is harder?   What does that say about its function?) 7.
Identify and diagram the Doesal Blood Vessel and the 5 Aortic Arches.  (What role do the arches play in the worm?
What is the equivalent organ – be careful here – in humans, and to what body system does it belong?  Why do humans
have less than five?)

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Given that the earthworm’s skin must be kept moist, and what organs that appear in humans appear to be missing in the
earthworm, what body system’s function is taken up here by the skin?
Identify and diagram the Seminal Vessicles and the Seminal Receptacles.  (What is the function of each?  What are the
equivalent organs in humans, and to what body system do they belong?)

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Identify and diagram the Suprapharyngeal Ganglia.  (What is its function?  What is the equivalent organ in humans, and
to what body system dos it belong?  Has the bilateral appearance been retained in humans?  If so or if not, what is it
about the human organ that supports your statement?  You will need to refer to specific structures in your answer
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Remove the intestine from the point where you started your incision.  (It might help to gently cut the intestine at one end
with the scalpal; be careful not to cut all the way through the worm.)  On either the underside of the intestine, or on the
bottom of the worm – depending on how gently you lifred up the intestine, you will find the Ventral Nerve Cord.
Diagram it.  (What is  – be specific as to direction – its function?  What is the equivalent organ in humans, and to what
body system dos it belong?  What aspect of this organ differentiates the earthworm from members of our phylum?)

Note the two layers of muscle, Circular and Longitudinal, that make up the wall of the organism.  It is the
12.alternating contraction of these two layers that make it possible for the earthworm to propel itself through
the soil.  As these two layers pull against each other (i.e., acting as an anchor for the opposing
contraction), what other body system’s function is taken up my the muscles here?
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Wipe off the dissecting microscope stage with a slightly moist paper towel (if necessary) and dry it thoroughly. 13.
Dispose of the worm, and any worm parts in the one trash can specified by the teacher. 14.
Rinse off the tools and dry them thoroughly before returning them to the tool tray. 15.
Rinse off the lid and and the tray and stack them as seen in the picture below.
Note: the trays need to be placed upside down at 90
angles to each other, with one edge of the bottom tray over the
edge of the sink to allow all of the trays to air-dry!
NOTE: This clean up
technique will be the same
on the last day for each
specimen. At the end of
each regular dissection day
prior to the last day for
that specimen, you will be
using the clean up
technique described
above. Image by Mr. Lazaroff
Clean up:
Normal Day Clean Up
Last Day Clean Up
Use a PENCIL!!  NOTE: Pen will NOT be accepted! 1.
Make the drawings “larger than life” size, as the specimens are so small. 2.
Draw the general shape (outline) and location of the organs, as the squiggles so many of you use to
“shade” your drawings make your drawings sloppy and hard to interpret.
Include Labels on all drawings. 4.
Labels should start outside the drawing, and be connected to the structure by arrows
with tips (===>).
The Tip of the arow should be touching the structure.
Be sure to include the magnification for any drawings done with the dissecting
Hang on to the drawings; they will all be handed in later, together with some questions to answer.
Day 1        Day 2         Top        Return to Mr. Lazaroff’s Biology

Keywords.  Cocoon;  development time;  earthworm;  fecundity;  hatching success;  temperature

J. Biosci.  |  Vol. 27  |  No. 3  |  June 2002  |  283–294  |  © Indian Academy of Sciences

Cocoon production, morphology, hatching pattern and fecundity in
seven tropical earthworm species – a laboratory-based investigation
Department of Zoology, MBB College, Agartala 799 004, India
*Corresponding author (Email,

Data on the reproductive biology of seven Indian species of earthworms, viz.  Perionyx excavatus Perrier,
Lampito mauritii  Kinberg,  Polypheretima elongata  (Perrier),  Pontoscolex corethrurus  (Muller),  Eutyphoeus
gammiei  (Beddard),  Dichogaster modiglianii  (Rosa) and Drawida nepalensis Michaelsen are presented. The
peregrine earthworms such as  Perionyx excavatus,  Pontoscolex corethrurus,  Dichogaster modiglianii, and
Polypheretima elongata are considered to be continuous breeders with high fecundity. Native Lampito mauritii
and Drawida nepalensis are semi-continuous and  Eutyphoeus gammiei discrete breeders. There is a dramatic
increase in cocoon production by most earthworm species of Tripura in the summer and monsoon with a
corresponding peak during April and July. Cocoon production decreased or ceased during winter. Temperature
affected the incubation period of cocoons. With increase in temperature, incubation period increased in the
endogeic worms,  Pontoscolex corethrurus,  Polypheretima elongata and Drawida nepalensis and decreased in
the epigeic worms,  Perionyx excavatus  and  Dichogaster modiglianii, within a temperature range between
28–32°C under laboratory conditions. There was a significant (P < 0×05) positive correlation between number of
hatchlings per cocoon and incubation period in  Lampito mauritii. High rate of cocoon production, short
development time with high hatching success, as well as continuous breeding strategies in the epigeic species
Perionyx excavatus  and  Dichogaster modiglianii  and the top soil endogeic species,  Pontoscolex corethrurus,
Drawida nepalensis  and  Lampito mauritii, indicate their possible usefulness in vermiculture. The giant anecic
worm,  Eutyphoeus gammiei, which has a very long cocoon development time, discrete breeding strategy and
very low rate of cocoon production, is not a suitable species for vermiculture.
[Bhattacharjee G and Chaudhuri P S 2002 Cocoon production, morphology, hatching pattern and fecundity in seven tropical earthworm
species – a laboratory-based investigation; J. Biosci. 27 283–294]

1.  Introduction
Population  dynamics, productivity and energy flow in
earthworms cannot be fully understood unless the life
cycle of the earthworm is known. Studies on the life
cycles of earthworms are also necessary for effective
Knowledge of the reproductive strategies of earth-
worms comes predominantly from studies on temperate
species (Evans and Guild 1948; Satchell 1967; Lavelle
1971, 1979; Bouché 1972; Reynolds 1973; Phillipson and
Bolton 1977; Elvira et al 1996; Nair and Bennour 1998;
Jiménez et al 1999). There are reports on the earthworm
resources of India including of its north-eastern states
(Gates 1972; Julka 1993a,b, 2001; Julka and Senapati
1987; Bano and Kale 1991; Chaudhuri and Bhattacharjee
1999; Halder 1999, 2000). However, information is
scanty regarding the biology and ecology of earthworm
species from tropical regions. Dash and Senapati (1980)
studied the morphology of cocoons of three tropical
earthworms, Lampito mauritii, Drawida willsi  and Octo-
chaetona surensis, and the effect of soil moisture and
temperature on the cocoon hatching process and the
emergence pattern of juveniles in the field. Most studies J. Biosci.  |  Vol. 27  |  No. 3  |  June 2002
Gautam Bhattacharjee and P S Chaudhuri

on the life cycles of tropical earthworms concern the
composting species Perionyx excavatus (Kale et al 1982;
Reinecke and Hallatt 1989; Hallatt et al 1990, 1992;
Edwards et al 1998). In Perionyx excavatus, Hallatt et al
(1990) studied the growth rate, rate of maturation, cocoon
production, the hatching success of cocoons, the incu-
bation period and the number of offspring per cocoon
under controlled laboratory conditions at different mois-
ture and temperature regimes.
The aim of this study was to describe cocoon morpho-
logy, and analyse cocoon development, hatching success,
dynamics of cocoon production, and fecundity in seven
species of Indian earthworms. Such information could
then be used to fit these earthworms into broad categories
of reproductive strategies and allow selection of appro-
priate species for vermiculture.
2.  Materials and methods
The study was carried out with seven tropical earthworm
species occurring in Tripura, a north-eastern state of
India. The climate is broadly divided into 3 seasons:
winter (November–February), summer (March–June) and
monsoon (July–October). Adult earthworms were collec-
ted by the digging and hand sorting method from pasture
and dung deposit sites in Sadar subdivision of Tripura,
located between latitude 22°51¢–24°32¢N and longitude
90°10¢–92°21¢E, between July and October 1998. Earth-
worms were acclimated in a ventilated laboratory until
December 1998. Earthworms were identified by the Zoo-
logical Survey of India, Kolkata. Based on our field
studies, the ecological category, habit, habitat and size
relationship of these earthworms are presented in table 1.
2.1  Culturing methods
Earthworms were not subjected to any controlled condi-
tion in the laboratory. Clay pots (4×5 l) containing suita-
ble food (culture medium), were used for rearing of
earthworms. Perionyx excavatus Perrier, a surface living
species, inhabits cowdung heaps, and air dried, sieved
(1 mm mesh) ground cowdung (200 g) free from any
foreign cocoon was used as feed for this species. Dicho-
gaster modiglianii  (Rosa), another surface living earth-
worm, is found in cowdung soil juncture and a mixture of
sieved cowdung (100 g) and garden soil (100 g) was used
as feed for this species.  For the other geophagous
species, ground, sieved pasture soil [2000 g for the giant
worm Eutyphoeus gammiei (Beddard), 600 g for the large
sized  Polypheretima elongata  (Perrier), 200 g each for
the small to medium sized  Pontoscolex corethrurus
(Muller),  Lampito mauritii Kinberg and  Drawida
nepalensis  Michaelsen] was used as food for culture.
Culture pots of each species received the prescribed
amount of food along with two earthworms. The moisture
level in the culture media was maintained close to the
field soil moisture of these earthworm species (table 1) at
70–80% (Perionyx excavatus), 28–42% (Dichogaster
modiglianii) and 25–35% (other species) by sprinkling
water with a hand spray on alternate days. Moisture
content of the substrates was measured periodically by
gravimetric method. Maximum average temperature of
the ventilated room (calculated from mean of actual
maximum temperature) varied from 19×6 (January) to
32×4°C (April) for the year 1999.
The cultures were maintained for one year (January
1999–December 1999). During October 1999 mortality
was noticed in some of the cultures containing  Euty-
phoeus gammiei that were later terminated. Death pro-
bably resulted due to stressful conditions such as
comparatively small containers and low substrate volume
for these giant earthworms.
2.2  Cocoon studies
The first experiment had five replicates for each species
and was aimed at studying fecundity and dynamics of
cocoon production. Cocoons were collected on 0×5 mm
mesh sieve every week, using gentle washing, and their
number was calculated on a per individual basis. The
second experiment had three replicates for each species
and was aimed at determining  the approximate timing
of cocoon production, incubation period and hatching
pattern. The size and weight of cocoons were also
measured. Before weighing, the cocoons were washed
lightly in distilled water to remove debris adhering to
the sticky hull. Here culture sets were carefully obser-
ved daily for cocoons, if any. The cocoons were imme-
diately isolated and incubated. In both experiments, old
culture media was replaced by the same amount of fresh
media at weekly intervals, so that food was not a limiting
2.3  Incubation of cocoons
After isolation, freshly laid cocoons were kept on moist
filter paper spread over water soaked cotton (having 80%
moisture) inside a petri-dish (one cocoon per dish). They
were housed in the same room as the experimental pots.
The maximum average room temperature during cocoon
development varied from 28–32°C. Cocoons were obser-
ved daily to record any external changes during incuba-
tion and to determine whether any hatchlings emerged.
Development time (incubation period) is the time lapse
(in days) from cocoon formation until the first hatchling
appeared. Number of hatchlings per cocoon and size of
hatchlings were also recorded. J. Biosci.  |  Vol. 27  |  No. 3  |  June 2002

Reproductive biol ogy of earthworms   285
J. Biosci .  |  Vol. 27   |  No. 3  |   June 2002

Table 1.  Ecological category, habitat and size relationship of seven species of earthworms of Tripura collected between July and October (1998).







Soil organic



Perionyx excavatus*  Megascolecidae  L 100–180
B 5–6
Phytophagous  Compost
heaps, leaf
0–15  4×5–12  6×4–7×4  20–28  10–70  Epigeic
Lampito mauritii  Megascolecidae  L 140–160
B 5–6
Phytogeophagous  Pasture  10–15  0×5–4×5  5×8–7×2  20–28  10–40  Top soil
Polypheretima elongata  Megascolecidae  L 200–250
B 5–7
Unpigmented  Geophagous  Pasture  30–45  2×5–4×5  6×9–7×2  20–28  10–40  Sub soil
Pontoscolex corethrurus*  Glossoscolecidae  L 70–90
B 4–5×2
Geophagous  Pasture  10–15  0×5–8×5  5×9–7×2  20–28  10–60  Top soil
Drawida nepalensis  Moniligastridae  L 40–50
B 2–3
Phytogeophagous  Pasture  10–15  0×5–2×5  6×5–7×0  20–26  10–40  Top soil
Dichogaster modiglianii*  Octochaetidae  L 25–40
B 2–3
Phytogeophagous  Soil–cow
0–10  2×5–8×5

5×7–7×2  20–28  10–60  Epigeic
Eutyphoeus gammiei  Octochaetidae  L 200–400
B 7–10
dorsally, lightly
Geophagous  Pasture
(living in
15–45  2×5–6×5  5×8–7×0  24–28  25–40  Subsoil

*Peregrine species. L, Length; B, breadth.

J. Biosci.  |  Vol. 27  |  No. 3  |  June 2002

Gautam Bhattacharjee and P S Chaudhuri

2.4  Statistical analysis
Significant differences, if any, in cocoon production
among 3 different seasons (winter, summer and monsoon)
with respect to room temperature for each earthworm
species except for  Lampito mauritii  was compared by
one-way ANOVA followed by critical difference (CD) at
5% level using the formula:
CD = t0×05,57 ×
Mse 2

(N = 60,  Mse = mean square error). In case of  Lampito
mauritii, pair-wise  t-test was used to compare significant
difference in cocoon production between summer and
monsoon (cocoon production stopped during winter in
this species). The correlation between the mean room
temperature and incubation period for  Perionyx exca-
vatus, Pontoscolex corethrurus, Dichogaster modiglianii,
Drawida nepalensis, Polypheretima elongata and between
number of hatchlings per cocoon and incubation period
for  Lampito mauritii were tested by simple regression
3.  Results
Mating was observed only in Perionyx excavatus on the
surface of the cultures during the day.
3.1  Cocoons: Morphology, size, development time
and emergence
Cocoons produced by  Perionyx excavatus were rough,
spindle shaped with bristles at the pointed end. In other
species, cocoons are either spheroidal (Pontoscolex  sp.,
Polypheretima sp., Eutyphoeus sp., Dichogaster sp., Dra-
wida  sp.) or ovoid (Lampito  sp.) with pointed ends on
either  side (figures 1 and 2). Among the seven earthworm
species studied, the largest cocoon (diameter 7 mm, fresh
weight 103 mg) was of the giant worm,  Eutyphoeus
gammiei  and  the smallest cocoon (diameter 1×3 mm, fresh
weight 1×5 mg) was of the smallest earthworm,  Dicho-
gaster modiglianii (table 2). Freshly laid cocoons of most
of the earthworms were opaque, but those of Pontoscolex
corethrurus  and Lampito mauritii were semi-transparent.
In  Lampito mauritii  2 to 3 zygotes were clearly visible
through the cocoon 4 to 5 days after cocoon laying,
although one of the zygotes generally degenerated later.
Blood capillaries first appeared in the cocoon of Lampito
mauritii  on the 8th day of development. The cocoon
became opaque and reddish due to increase in vascu-
larization during the 10th to 11th days of development.
The hatchlings of all species of earthworms emerged
through a hole made at the pointed end of the cocoon
(figure 2). In most of the earthworm species, one hatch-
ling emerged out from a single cocoon. However in
Lampito mauritii about 53% of the cocoons produced
more than one hatchling (2, rarely 3). Rare emergence
of more than one hatchling per cocoon was also recorded

Figure 1.  Cocoons of earthworms (from left to right:  Eutyphoeus gammiei, Lampito mauritii, Pontoscolex corethrurus,
Polypheretima elongata, Drawida nepalensis, Perionyx excavatus and Dichogaster modiglianii).
J. Biosci.  |  Vol. 27  |  No. 3  |  June 2002

Reproductive biology of earthworms

in  Drawida nepalensis  (20%) and  Polypheretima elon-
gata (11%).
Development time of cocoons was short in the topsoil
endogeic worms,  Lampito mauritii  (15  days),  Drawida
nepalensis  (25 days) and  Pontoscolex corethrurus  (29
days) and long (50 days) in the subsoil endogeic earth-
worm, Polypheretima elongata (table 2). Prolonged deve-
lopment time (110 days) was observed in the cocoon of
the subsoil anecic worm,  Eutyphoeus gammiei. Deve-
lopment time of cocoons was very short (13–14 days) in
the epigeic worms,  Perionyx excavatus  and Dichogaster
modiglianii. A significant positive linear correlation (P
< 0×05) between mean room temperature (28–32°C) and
incubation period in Pontoscolex corethrurus, Polyphere-
tima elongata  and Drawida nepalensis (figure 3a–c) and
a significant negative linear correlation (P < 0×05) between
the same variables in Perionyx excavatus and Dichogas-
ter modiglianii were observed (figure 3d–e). Interestingly,
there was a significant (P < 0×05) positive correlation
between number of hatchlings per cocoon and the
incubation period in Lampito mauritii (figure 4).
Hatching success was strikingly higher in Pontoscolex
corethrurus  (85%),  Dichogaster modiglianii (78%),  and
Lampito mauritii  (60%)  compared with  Polypheretima
elongata  (40%),  Drawida nepalensis  (38%) and  Euty-
phoeus gammiei (20%). The mean hatching  success of
cocoons in Perionyx excavatus was 53% (table 2).
3.2  Dynamics of cocoon production
Pontoscolex corethrurus, Dichogaster modiglianii, Poly-
pheretima elongata and Perionyx excavatus showed year-
round cocoon production (continuous breeders) under
laboratory conditions (figure 5). Cocoon production in
Lampito mauritii and Drawida nepalensis continued from
March to November (semi-continuous breeders).  Euty-
phoeus gammiei is regarded as a discrete breeder because
its cocoon production was restricted to the period
between March and May under laboratory conditions.
In  Lampito mauritii  cocoon production ceased and in
other species it declined during winter (figure 5). In most
of the species studied, there was significant increase (P
< 0×05, n = 57) in cocoon production during both summer
and monsoon compared to winter (table 3). Cocoon
production was significantly higher (P < 0×05,  n = 57) in
the summer compared to the monsoon and winter season
in Perionyx excavatus  and Drawida nepalensis  (table 3).
In other species, viz. Pontoscolex corethrurus, Polyphere-
tima elongata,  Dichogaster modiglianii  and  Lampito
mauritii, the difference in cocoon production during
summer and rainy season was not significant (P > 0×05,
n = 38 in  Lampito mauritii and  n = 57 in other species).
In peregrine species, Polypheretima elongata and Dicho-
gaster modiglianii, there was no significant difference
(P > 0×05,  n = 57) in cocoon production among the three
seasons (table 3).
Lampito mauritii,  Polypheretima elongata,  Drawida
nepalensis  and  Dichogaster modiglianii  exhibited peaks
in cocoon production twice a year, during April and July
when maximum average room temperature varied from
30 to 32°C.  Perionyx excavatus, which showed three
annual peaks of cocoon  production (March, July and
October) had a sudden and large peak during March
when maximum room temperature was 28×5°C (figure 5).
Pontoscolex corethrurus  showed a relatively steady rate
of cocoon production during the major part of the year,
with a single peak of production during April (figure 5).
Cocoon production in earthworms declined after October
when maximum average room temperature fell below
27°C, although  Pontoscolex corethrurus,  Polypheretima
elongata and  Dichogaster modiglianii  maintained their
cocoon production when the temperature was 21°C.
3.3  Fecundity
The highest fecundity (i.e. the number of cocoons produ-
ced per adult in one year) was recorded for the epigeic
earthworm,  Perionyx excavatus. This species produced
156 cocoons adult
under laboratory conditions
(table 2).  Eutyphoeus gammiei  (anecic worm) had the
lowest value of 1×0 cocoon adult
. Of the other
species  Pontoscolex corethrurus had the highest fecun-
dity followed by Dichogaster modiglianii, Lampito mauritii,
Polypheretima elongata and Drawida nepalensis (table 2).
4.  Discussion
While cocoons are produced by cross-fertilization
between two adult worms in many species, in others there
may be self-fertilization or parthenogenesis. The shape,

Figure 2.  Emergence of hatchling from the cocoon of  Euty-
phoeus gammiei.
Gautam Bhattacharjee and P S Chaudhuri

Table 2.  Biological features of cocoons of the seven earthworm species used (means ± standard errors).


Cocoons studied (n)  40  40  40  40  40  40  5
Morphology  Spindle shaped  Spheroidal  Oval  Spheroidal  Pear shaped  Onion shaped  Spheroidal
Length (mm)  6×52 ± 0×44    5×0 ± 0×28    5×0 ± 0×4    3×6 ± 0×35    2×0 ± 0×28    4×6 ± 0×21  7×4 ± 0×45
Breadth (mm)  2×1 ± 0×26  3×2 ± 0×33  2×8 ± 0×17  2×8 ± 0×17  1×3 ± 0×1  3×0 ± 0×28    6×8 ± 0×33
Colour (oxidized/aged)  Dark straw  White  Light straw  Yellowish  Off-white   Reddish  Dark grey
Ornamentation  Bristles at the
pointed end
Absent  Absent  Two small
curved pointed
One end with single
pointed end and other
bears a circlet of bristles
Well developed
pointed end on
either side
Fresh weight (mg)   5×0 ± 0×4  21×0 ± 0×6  20×6 ± 0×8  30×2 ± 1×8  1×5 ± 0×04  14×4 ± 0×5  103×2 ± 1×8
Time course of cocoon
Continuous  Continuous  Semi-
Continuous  Continuous  Semi-continuous  Discrete
Cocoon production

156  118  43  23  68  29  1
Development time (days)  12×80 ± 0×31
(n = 21)
29×03 ± 1×40
(n = 33)
14×93 ± 0×51
(n = 31)
49×53 ± 1×77
(n = 15)
14×16 ± 0×48
(n = 31)
24×26 ± 1×58
(n = 15)
(n = 1)
Hatching success (%)  52×50   85   60   40   77×50   37×50   20×0
Hatchlings cocoon–1
1×30 ± 0×11
(n = 21)
1×03 ± 0×02
(n = 33)
1×67 ± 0×11
(n = 31)
1×33 ± 0×12
(n = 15)
(n = 31)
1×80 ± 0×19
(n = 15)
(n = 1)
Hatchling size (mm)
(length × breadth)
4×8 ± 0×52 ×
1×0 ± 0×0
(n = 5)
6×60 ± 0×45 ×
2×0 ± 0×44
(n = 5)
12×7 ± 1×6 ×
1×4 ± 0×21
(n = 5)
24×0 ± 1×5 ×
1×8 ± 0×17
(n = 5)
5×8 ± 0×33 ×
1×0 ± 0×0
(n = 5)
7×8 ± 0×76 ×
1×4 ± 0×21
(n =5)
50×0 ×
(n = 5)
Room temperature
during incubation (°C)
31×07 ± 0×26  30×11 ± 0×16  29×71 ± 0×27  30×38 ± 0×15  30×85 ± 0×14  30×35 ± 0×24  30×46
Room temperature
during hatching (°C)
29×52 ± 0×25  29×76 ± 0×34  29×60 ± 0×49  30×61 ± 0×53  29×88 ± 0×31  29×56 ± 0×60  28×0

300  Au
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288  Gautam Bhattacharjee and P S Chaudhuri  J. Biosci.  |  Vol. 27  |  No. 3  |  June 2002

Reproductive biology of earthworms

size, development time and hatching success of cocoons
differ greatly among earthworm species. The highest and
lowest size and weight of cocoons were found in the
giant anecic worm Eutyphoeus gammiei  and the smallest
epigeic  earthworm  Dichogaster modiglianii  respec-
tively.  Lavelle (1981)  and Senapati and Sahu (1993)
found a positive relationship between the size of the
adults and the cocoons produced by earthworms.
Edwards and Bohlen (1996) however proposed that
cocoon size is not always correlated with adult size. Tufts

Figure 3.  Linear regression analysis between temperature and incubation period in different earthworm species. (a) Pontoscolex
corethrurus, (b) Drawida nepalensis, (c) Polypheretima elongata, (d) Perionyx excavatus and (e) Dichogaster modiglianii.

(a)  (b)
(e) J. Biosci.  |  Vol. 27  |  No. 3  |  June 2002

Gautam Bhattacharjee and P S Chaudhuri

J. Biosci.  |  Vol. 27  |  No. 3  |  June 2002
of bristles at the pointed ends of cocoons in  Perionyx
excavatus and Dichogaster modiglianii are  adaptive fea-
tures of these epigeic species that enable them to adhere to
the litter in their surroundings. Viljoen and Reinecke
(1989) reported fibrous tips at both ends of the cocoon in
the African epigeic worm, Eudrilus eugeniae.
The development time of cocoons varies considerably
among earthworm species. Among endogeic earthworms,
development time of cocoons was short in topsoil endo-
geic worms,  Lampito mauritii  (15 days), Drawida nepa-
lensis (25 days) and  Pontoscolex corethrurus  (29 days)
and long in the subsoil endogeic earthworm,  Polyphere-
tima elongata  (50 days).  Development time of 28 days
was reported for the cocoons of Polypheretima elongata
(Sahu and Senapati 1991) and  Lampito mauritii (Dash
and Senapati 1980). Kaushal et al (1995) reported an
incubation period of 30×5 days for the cocoons of
Drawida nepalensis in moist filter paper under 25°C
temperature regime. The above values on cocoon deve-
lopment time for these earthworms species  are different
from our present observation due to different methods
adopted by the investigators. A prolonged development
time (110 days) was found for the cocoons of the subsoil
anecic worm,  Eutyphoeus gammiei. The development
time of cocoons was very short in the epigeic worms,
Perionyx excavatus (13 days) and Dichogaster modiglianii
(14 days). Senapati and  Sahu (1993) reported a mean
incubation period of 7 days for  Dichogaster bolaui, a
small, tropical, epigeic worm.
Temperature affects the incubation period of cocoons.
With increase in room temperature, incubation period
increased in endogeic worms,  Pontoscolex corethrurus,
Polypheretima elongata and  Drawida nepalensis,  and
decreased in epigeic worms,  Perionyx excavatus and
Dichogaster modiglianii. Reinecke et al (1992) reported
a mean incubation period of 17×8 days and 15×3 days for
cocoons of Perionyx excavatus  incubated at 25°C and at
25–37°C, respectively. They further reiterated that tem-
peratures higher than 25°C decreased the mean incuba-
tion period in the epigeic worms  Perionyx excavatus,
Eudrilus eugeniae and  Eisenia fetida. According to
Holmstrup et al (1991) the threshold temperature for
hatching should be regarded as an adaptation to the
particular habitat condition in which the species lives.
Increase in the incubation period with increase in the
number of hatchlings per cocoon in  Lampito mauritii

Figure 4.  Linear regression analysis between number of hatch-
lings per cocoon and incubation period in Lampito mauritii.

Figure 5.  Number of cocoons produced (means ± SE) per
worm per month for six species of earthworms.

Perionyx excavatus
Pontoscolex corethrurus

Lampito mauritii
Polypheretima elongata

Drawida nepalensis
Dichogaster modiglianii
J. Biosci.  |  Vol. 27  |  No. 3  |  June 2002

Reproductive biology of earthworms

results from delayed development due to limited resource
utilization by all the embryos within the same cocoon.
Edwards (1988) reported that development time of
cocoons for temperate epigeic worms was 32–73 days in
Eisenia fetida, 40–126 days in Dendrobaena veneta, and
for tropical epigeic worms was 13–27 days in  Eudrilus
eugeniae and 16–21 days in Perionyx excavatus. Accord-
ing to Senapati and Sahu (1993) incubation period, in
general, ranges from 3 to 30 weeks in temperate worms
and 1 to 8 weeks in tropical worms.
Compared to the deep burrowing subsoil endogeic
worm Polypheretima elongata  and the anecic earthworm
Eutyphoeus gammiei, hatching success was higher in the
epigeic worms  Perionyx excavatus and  Dichogaster
modiglianii and the top soil endogeic worms Pontoscolex
corethrurus  and Lampito mauritii, that face less compe-
tition in the surface soil with its less predictable environ-
ment. The mean hatching success of cocoons  in Perionyx
excavatus was 53%, which is close to the figure of 50%
and far below that of 63×4% determined by Loehr et al
(1984) and Hallatt et al (1990) respectively. Interes-
tingly, Hallatt et al (1990) reported that hatching success
of the cocoons of  Perionyx excavatus  was low when
these were produced by newly matured non-mated worms
(i.e. by self-fertilization or parthenogensis). Our value on
hatching success in  Drawida nepalensis  (37×5%) is far
lower than the value (84%) reported for the same species
under controlled conditions by Kaushal et al  (1995). The
species we studied, with few exceptions, produced one
hatchling  per cocoon, although emergence of two (some-
times three) juveniles from the cocoons of  Lampito
mauritii and Drawida nepalensis was not rare. Dash and
Senapati (1980) and Kaushal et al (1995) also reported
rare emergence of two juveniles from cocoons of Lampito
mauritii and  Drawida nepalensis  respectively. Mean
number of hatchlings per cocoon was 3×3, 2×3 and 1×1 for
the cocoons of the epigeic earthworms  Eisenia fetida,
Eudrilus euginiae and  Perionyx excavatus respectively
(Edwards 1988).
Earthworms are continuous or semi-continuous bree-
ders, producing ova at most times of the year (Olive and
Clark 1978).  Perionyx excavatus,  Pontoscolex corethru-
rus, Dichogaster modiglianii and Polypheretima elongata
are peregrine earthworms (Fragoso et al 1999) that are
continuous breeders with high fecundity. Continuous
breeding strategies with high fecundity should be con-
sidered as adaptive features of these  peregrine worms.
The widely distributed native species, viz. Lampito mau-
ritii and  Drawida nepalensis (Fragoso et al 1999) are
semi-continuous breeders and  Eutyphoeus gammiei  with
restricted north-eastern distribution (Halder 2000) is a
discrete breeder. In  Drawida nepalensis which attains
sexual maturity within 45 days, Kaushal et al (1995)
reported cocoon production for only 5 months after
sexual maturity. Year-round cocoon production with five
cocoon peaks in  Polypheretima elongata under field
conditions was reported by Sahu and Senapati (1991).
The dramatic increase in cocoon production by most
earthworm species in summer and monsoon with corres-
ponding peaks during April and July were probably due
to favourable temperature conditions in Tripura at that
time. The least number of cocoons were produced by
these worms in the winter months due to fall in tem-
perature. Dash and Senapati (1980) reported that under
field conditions earthworms of Orissa produced cocoons,
not in the harsh summer (when air temperature is around
45°C) but in the monsoon and post-monsoon seasons
(air temperature < 30°C). In fact,  temperatures beyond
optimum levels act as cues for decreased neurosecretory
activity, thus affecting  cocoon production (Olive and
Clark 1978).
Cocoon production (number/adult/year) varies with
species and environmental conditions (Evans and Guild
1948; Satchell 1967). Among the seven earthworm  spe-
Table 3.  Number of cocoons produced (means ± standard errors) per earthworm species
during three seasons.

Earthworm species

Seasons and
room temperature


± 1×0
± 0×98
± 0×26
± 0×25
± 0×89


± 3×4
± 1×86
± 0×64
± 0×67
± 1×0
± 0×75
± 2×0
± 1×51
± 0×39
± 0×59
± 0×61
± 0×78

Same letters in columns indicate non-significant variation between seasons for each species (P > 0×05).
n = 20 for each mean value.
J. Biosci.  |  Vol. 27  |  No. 3  |  June 2002

Gautam Bhattacharjee and P S Chaudhuri

J. Biosci.  |  Vol. 27  |  No. 3  |  June 2002
cies studied, highest and lowest cocoon production under
fluctuating laboratory conditions (24–32°C) was by the
epigeic worm  Perionyx excavatus (156 cocoons adult

) and the anecic worm  Eutyphoeus gammiei
(1 cocoon adult
). Edwards (1988) reported pro-
duction of 1014 cocoons adult
in Perionyx exca-
vatus at 25°C which according to him is the optimum
temperature for cocoon production in this species. Values
of cocoon production at the rate of 19 adult
Polypheretima elongata  (Sahu and Senapati 1991), 14
for  Lampito mauritii (Dash and Senapati
1980) and 68 adult
for  Pontoscolex corethrurus
(Barois et al 1999) under field condition are lower than
that observed in our present studies on cocoon production
by  Polypheretima elongata (23 adult
),  Lampito
mauritii (43 adult
) and  Pontoscolex corethrurus
(118 adult
). Senapati and Sahu (1993) postulated
that size of the worms bears a negative relationship with
cocoon production. Greater rate of cocoon production by
small to medium sized epigeic earthworms  Dichogaster
modiglianii  and  Perionyx excavatus, and top soil endo-
geic worms  Pontoscolex corethrurus  and Lampito mau-
ritii  was due to exposure to their high mortality risk
environment. Lee (1985) correlated the higher risk of
mortality in early life with higher rate of cocoon produc-
tion. On the contrary, large, burrowing subsoil earth-
worms, Eutyphoeus gammiei and Polypheretima elongata
produced much fewer cocoons compared to the topsoil
species studied. Jiménez et al (1999) also reported a very
low rate of cocoon production under field conditions by
Martiodrilus carimaguensis, a giant deep burrowing earth-
worm from Colombia. According to Satchell (1967)  there
is a clear relationship between the number of cocoons pro-
duced and their location in the soil profile. Those species
that can move into deeper soil layers and are  protected
from adverse conditions produce fewest cocoons, whereas
those living near the surface, and facing adverse condi-
tions, produce many more cocoons. Cocoon production
and time for maturation of cocoons vary with species,
population density, age structure and external factors espe-
cially soil temperature, moisture and energy content of
the available food (Lee 1985; Edwards and Bohlen 1996).
A relationship between reproductive strategies and
ecological categories in tropical earthworms was pro-
posed by Lavelle et al (1998) and Barois et al (1999).
They distinguished four groups of earthworms. These are
group 1: large native endogeic and anecic species with
low fecundity (0×5–3×1 cocoons adult
) and only
one hatchling per cocoon; group 2: medium-sized meso-
humic endogeic species with intermediate fecundity
(1×3–45 cocoons adult
); group 3: small mainly
polyhumic endogeic species with intermediate fecundity
(10–68 cocoons adult
) and usually one hatchling
per cocoon; and group 4: generally small, mainly exotic
and epigeic species with very high fecundity (50–350
cocoons adult
) and up to three hatchlings per
cocoon. From our studies it appears that Eutyphoeus  sp.
belongs to group 1,  Polypheretima  sp. to group 2, Dra-
wida  sp.,  Pontoscolex sp. and  Lampito sp. to group 3,
Perionyx and Dichogaster sp. to group 4 categories.
Pianka (1970) on the basis of response to selection
pressure, classified organisms into two categories:  r-
selected and K-selected species. High fecundity (i.e. high
rate of cocoon production), short incubation period with
high hatching success in epigeic (Dichogaster modigli-
anii  and  Perionyx excavatus) and top soil endogeic
worms (Pontoscolex corethrurus,  Drawida nepalensis
and Lampito mauritii) are probably adaptive strategies of
‘r’-selected worms (Sahu and Senapati 1991) to enable
them to survive drastic environmental changes, especially
heat, drought and predation in the top soil. Large body
size, low fecundity, long incubation period and low
hatching success in the subsoil anecic worm, Eutyphoeus
gammiei  and endogeic  Polypheretima elongata  are cha-
racteristics of species with  ‘K’-selection (Sahu and Sena-
pati 1991), where the environment is predictable and
benign and competition is intense (Wallwork 1983).
The giant worm,  Eutyphoeus gammiei, that displays a
very long cocoon development time and a discrete and
very low rate of cocoon production, is not a suitable
species for vermiculture. The more continuous and high
rate of cocoon production as well as higher hatching rate
in  Perionyx excavatus,  Dichogaster modiglianii,  Ponto-
scolex corethrurus,  Drawida nepalensis  and  Lampito
mauritii  indicate their possible usefulness in vermi-
culture-based biotechnology.

The authors express their sincere thanks to Prof. J P Roy
Chowdhuri for providing laboratory facilities, Prof. Radha
D Kale and Dr K E Lee for their valuable comments on
the paper, Prof. D K Nanda, Department of Zoology,
Calcutta University for encouragement and Dr K R
Halder, Zoological Survey of India, Kolkata, for identi-
fication of earthworms,  Prof B K Agarwal, Tripura Uni-
versity and Mr Anil Das, Department of Statistics, MBB
College for statistical analysis. Financial assistance from
Indian Council of Agricultural Research, New Delhi is
gratefully acknowledged.

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MS received 11 July 2001; accepted 23 April 2002

Corresponding editor: RENEE M BORGES