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A few species exhibit pseudogamous parthogenesis, meaning that mating is necessary to stimulate reproduction, even though no male genetic material passes to the offspring. [37] Earthworm mating occurs on the surface, most often at night. Earthworms are hermaphrodites; that is, they have both male and female sexual organs. The sexual organs are ...
The European nightcrawler (Dendrobaena hortensis) is a medium-small earthworm averaging about 1.5 g when fully grown. Generally blueish, pink-grey in color with a banded or striped appearance, the tips of their tails are often cream or pale yellow. When the species has not been feeding, it is pale pink. The species is usually found in deep ...
Earthworm head. Lumbricus terrestris is relatively large, pinkish to reddish-brown in colour, generally 110–200 millimetres (4.3–7.9 in) in length and about 7–10 millimetres (0.28–0.39 in) in diameter. It has around 120–170 segments, often 135–150. The body is cylindrical in the cross section, except for the broad, flattened ...
The maximum length of a specimen is 10 cm (4 in). Worms raised in laboratory environment are slightly shorter, with 4 to 6 cm (1.57 - 2.36 in) long bodies. An adult individual has approximately 150 to 250 1.5 mm wide segments, [1] each of which has the ability to regenerate into a new individual when separated from the rest of the animal. In ...
Parthenogenesis occurs naturally in some plants, algae, invertebrate animal species (including nematodes, some tardigrades, water fleas, some scorpions, aphids, some mites, some bees, some Phasmatodea, and parasitic wasps), and a few vertebrates (such as some fish, [6] amphibians, reptiles, [7] [8] [9] and birds [10] [11] [12]). This type of ...
Sexual reproduction is the most common life cycle in multicellular eukaryotes, such as animals, fungi and plants. [6][7] Sexual reproduction also occurs in some unicellular eukaryotes. [2][8] Sexual reproduction does not occur in prokaryotes, unicellular organisms without cell nuclei, such as bacteria and archaea.
Caecilians feed on small subterranean creatures such as earthworms. The body is cylindrical and often darkly coloured, and the skull is bullet-shaped and strongly built. Caecilian heads have several unique adaptations, including fused cranial and jaw bones, a two-part system of jaw muscles, and a chemosensory tentacle in front of the eye. The ...
The Chaetognatha / kiːˈtɒɡnəθə / or chaetognaths / ˈkiːtɒɡnæθs / (meaning bristle-jaws) are a phylum of predatory marine worms that are a major component of plankton worldwide. Commonly known as arrow worms, they are mostly nektonic; however about 20% of the known species are benthic, and can attach to algae and rocks.