Folk names for the earthworm include "dew-worm", "rainworm", "nightcrawler", and "angleworm" (from its use as fishing bait). Theoretical cladistic studies have placed them in the suborder Lumbricina of the order Haplotaxida, but this may soon change. In classical systems, they were in the order Opisthopora since the male pores opened posterior to the female pores, although the internal male segments are anterior to the female. "Earthworm" is the common name for the largest members of Oligochaeta (which is a class or subclass depending on the author). As invertebrates, they lack a true skeleton, but they maintain their structure with fluid-filled coelom chambers that function as a hydrostatic skeleton. Each individual has both male and female genital pores. When mating, two individual earthworms will exchange sperm and fertilize each other's eggs. Įarthworms are hermaphrodites: each carries male and female reproductive organs. Similar sets of muscles line the gut, and their actions move digesting food toward the worm's anus. Large numbers of chemoreceptors concentrate near its mouth.Ĭircumferential and longitudinal muscles edging each segment let the worm move. Its central nervous system consists of two ganglia above the mouth, one on either side, connected to a nerve running along its length to motor neurons and sensory cells in each segment. It has a central and peripheral nervous system. It has a double transport system made of coelomic fluid that moves within the fluid-filled coelom and a simple, closed circulatory system. Īn earthworm respires (breathes) through its skin. An earthworm's digestive system runs the length of its body. This organic matter includes plant matter, living protozoa, rotifers, nematodes, bacteria, fungi, and other microorganisms. Įarthworms are commonly found in soil, eating a wide variety of organic matter. They occur worldwide where soil, water, and temperature allow. They exhibit a tube-within-a-tube body plan they are externally segmented with corresponding internal segmentation and they usually have setae on all segments. Terrestrial invertebrate, order OpisthoporaĪn unidentified earthworm species with a well-developed clitellumĪn earthworm is a terrestrial invertebrate that belongs to the phylum Annelida.
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