Description
An “Earthworm: External Morphology & Reproduction” (55×90 cm) educational chart presents clear, colored diagrams of the earthworm’s segmented body, key external features, and detailed notes on its reproductive systems and process, supporting zoology teaching and laboratory reference.
External Morphology
Body Plan and Segmentation: The earthworm is long, cylindrical, bilaterally symmetrical, and divided into 100–120 rings or segments (somites). The dorsal surface has a visible dark blood vessel; the ventral side features genital openings and papillae.
Key Features:
Mouth and Prostomium: Crescent-shaped mouth at the anterior end, just below a lobe called the prostomium, which assists in digging.
Clitellum: A prominent thickened glandular ring encircling segments 14–16 in mature worms, critical for reproduction and cocoon formation.
Setae: S-shaped bristles in each segment (except the first, last, and clitellum) for locomotion; diagram often shows arrangement and structure.
Apertures: Mouth (1st segment), anus (last segment), spermathecal pores (segments 5/6 to 8/9), male genital pores (18th segment), and female genital pore (14th segment).
Reproductive System & Process
Hermaphroditism: Each earthworm has both male and female reproductive organs (bisexual).
Male System: Testes (segments 10–11), vasa deferentia, accessory glands, prostate gland, and male pores (18th segment).
Female System: Ovaries, oviducts, and female genital pore (14th segment).
Spermathecae: Pairs of storage sacs (segments 6–9) for receiving sperm during mating.
Reproductive Process:
Earthworms reproduce sexually via cross-fertilization. During copulation, two worms align ventrally, exchange sperm, and store it in spermathecae.
Clitellum secretes a mucus cocoon; eggs, stored and received sperm, and nutritive fluid are deposited and the cocoon slips off, where fertilization occurs externally. Direct development leads to young hatchlings.
This chart is ideal for visualizing anatomy, identifying reproductive and external features, and explaining earthworm biology in school or undergraduate study.