albumin:
A fluid filled with water-soluble proteins.
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aestivation:
A period of inactivity, or dormancy, induced by unfavorable conditions. During
aestivation, the earthworm curls up into a knot and becomes quite
pink.
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anecic:
A habitat classification
term. These earthworms live in deep vertical burrows, but feed at
or near the soil surface, especially at night.
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annelid:
An organism that has a segmented body, giving
it a ringed appearance. The segments are arranged one beside each
other symmetrically along the length of the earthworm to form the
body.
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anus:
See periproct
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calcareous:
Something that is made of or contains calcium carbonate; in soil, can occur as chalk or limestone.
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castings:
Earthworm feces; the voided earth and other waste materials that are
deposited on the surface of the ground. Not all species form their
casts above ground.
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circular muscles:
See muscles
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clitellate adult:
Any earthworm with a developed clitellum and genital markings.
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clitellum:
(see figure 1) A swelling in the skin near the head that secretes material to form cocoons. The clitellum forms a band that can be flared,
non-flared, saddle shaped, or annular. The clitellum is generally found between segments 26-33.
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cocoon:
A sac that contains the earthworm’s eggs. The cocoon
is formed at the clitellum, and then travels from the clitellum to
the head. Here it slides off the earthworm’s body and is deposited into the soil.
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coelom:
The cavity between the body wall and the food (alimentary) canal.
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crop:
A widened portion of the digestive system that lacks the
muscularity of the gizzard. It is located after the esophagus, but
before the gizzard. An area where food is digested.
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dorsal pores:
The small holes located in the intersegmental
furrows down the middle of the earthworm’s back. These holes
lead to the coelomic cavity. The term first dorsal pore 5/6
means that this is the first dorsal pore and it is located between
segments 5 and 6.
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endogeic:
A habitat classification term. These earthworms burrow
continuously to form a network of channels – some vertical and
some horizontal in the rhizosphere. The majority of the burrows are
horizontal.
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epidermis:
Skin; the outer cellular layer of the body wall, which secretes mucus.
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epigeic:
A habitat classification term. These earthworms are not
strong burrowers, and live in the uppermost layers of the soil or
litter layer (i.e. decaying plant debris, or compost). They can form
some shallow vertical burrows where they temporarily escape from drought,
heat, and disturbances.
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epilobic:
See prostomium.
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exotic:
Introduced through human activity to an area; from a foreign location.
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flared clitellum:
See clitellum.
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genital markings:
Glandular swellings, pits or grooves of the epidermis (skin). See genital tumescences.
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genital tumescences (GT):
(see figure 1) Areas of modified
epidermis without distinct boundaries, through which follicles of
genital setae open.
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gizzard:
The muscular portion of the digestive system
where food is digested. It is located immediately after
the crop, and just before the intestine.
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hermaphrodite:
An animal that has both male and female reproductive organs.
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indigenous:
Belonging to the local area, native and not imported from anywhere.
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infiltration rate:
The amount of time required for a known amount
(volume or weight) of water to soak through the soil.
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intersegmental furrow:
The area between two consecutive segments.
It is here where the skin is thinnest and where, in pigmented species,
color is lacking.
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iridescence:
Shimmering colours on the surface of the earthworm's skin as a result
of refracted light. Green and blue are common iridescent colours.
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juveniles:
Those earthworms without genital markings such as the clitellum, tubercula
pubertatis, or genital tumescence. This stage of the life cycle is
located between the hatchling phase and the appearance of genital
markings (adult stage).
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litter:
Dead plant and animal material on the surface of the ground.
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longitudinal muscles:
See muscles
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midden:
the mound of soil surrounding the burrows of soil dwelling organisms.
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mouth:
The opening to the alimentary canal located in the peristomium.
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muscles:
Earthworms travel by coordinating two kinds of muscles: circular and
longitudinal muscles. Both are located under the epidermis. When the
circular muscles contract, the segments become thinner (decrease in
segment diameter), the earthworm lengthens and moves forward. When
the longitudinal muscles contract, the segments become thicker (increase
in segment diameter), and the earthworm shortens.
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Oligochaeta:
One of the taxonomic classes in the phylum Annelida. Members
of this class have segmented bodies, setae on all segments (except
the peristomium and periproct), a true coelom, a closed vascular system,
and crawl using circular and longitudinal muscles.
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ovum (egg):
A mature reproductive cell of female animals.
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parthenogenesis:
Reproduction without fertilisation (joining of egg and sperm).
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periproct:
(see figure 1) The last segment of the earthworm’s body; contains the anus.
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peristomium:
(see figure1) The first segment of the earthworm’s body; contains the mouth.
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pH:
An indication of soil acidity or alkalinity, which is expressed
on a pH scale (0-14). A pH less then 7 is acidic, 7 is neutral, and
greater then 7 is alkaline.
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pharynx:
The portion of the gut between the mouth and the esophagus.
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polymorphism:
The occurrence of slightly different looking individuals
within the same species; slight variations within one species.
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postclitellate adult:
Earthworms who have passed their reproductive
period. They no longer have a clitellum, but do show a discolouration
where the clitellum and genital markings were once located.
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prostomium:
(see figure 1) The lobe of skin that projects out in front
of the first body segment (peristomium). It is located above the mouth,
and there are three formations as seen in dorsal view.
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rhizosphere:
The area immediately around plant roots, including the
roots itself. This is an area of intense microbial activity, where
plants, microorganisms, other soil organisms, and soil structure and
chemistry, interact in complex ways.
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secondary annulation:
The small furrows (wrinkles) that occur in-between the intersegmental furrows.
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segment:
The small rings that surround the length of the earthworm’s
body. They are simply folds in the skin.
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setae:
(see figure 1) The bristles (or hairs) that are found on
an earthworm’s body. They help the earthworm to move and act
to sense the environment.
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setal pairings:
(see figure 1) The arrangement of the setae
on the earthworm’s body. Three arrangements exist:
closely paired, widely paired, and separate.
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sperm:
Male reproductive cells.
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spermathecae:
An organ in which sperm are stored.
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tubercula pubertatis (TP):
(see figure 1) Glandular swellings
that occur on both sides of the clitellum. They are not always present,
and they can be continuous or discontinuous with the clitellum. Their
size and shape may vary from long narrow bands, triangles, or sucker-like
shapes, depending on the species.
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