Cloaca (redirected from cloacal)

cloaca (klōā`kə), in biology, enlarged posterior end of the digestive tract of some animals. The cloaca, from the Latin word for sewer, is a single chamber into which pass solid and liquid waste materials as well as the products of the reproductive organs, the gametes. Cloacas are found in amphibians, reptiles, birds, and lower mammals; higher mammals have a separate rectal outlet, the anus. The term cloaca is also used for analogous chambers in many invertebrates, such as worms of the phylum Nematoda.

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cloaca

In vertebrates, common chamber and outlet into which the intestinal, urinary, and genital tracts open. It is present in amphibians, reptiles, birds, some fishes (e.g., sharks), and monotreme mammals but is absent in placental mammals and most bony fishes. Certain animals (e.g., many reptiles and some birds, including ducks) have an accessory organ (penis) within the cloaca that is used to direct the sperm into the female's cloaca. Most birds mate by joining their cloacas in a “cloacal kiss”; muscular contractions transfer the sperm from the male to the female.

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cloaca

a cavity in the pelvic region of most vertebrates, except higher mammals, and certain invertebrates, into which the alimentary canal and the genital and urinary ducts open

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cloaca [klō′ā·kə]

(invertebrate zoology)

The chamber which functions as a respiratory, excretory, and reproductive duct in certain invertebrates.

(vertebrate zoology)

The chamber which receives the discharges of the intestine, urinary tract, and reproductive canals in monotremes, amphibians, birds, reptiles, and many fish.

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cloaca

An underground conduit for drainage; a sewer, esp. in ancient Rome.

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Cloaca 

the broadened extremity of the hindgut of some vertebrate animals. The wall of the cloaca is covered with a many-layered epithelium. The ureter, the genital ducts (sperm ducts or oviducts), and the urinary bladder open into the cloaca. It is found in certain cyclostomes (hagfish) and fishes (sharks, skates, dipnoans and pipefish) and in all amphibians, reptiles, and birds. The cloaca is found in mammals of the subclass Prototheria. In other mammals a cloaca is found only in the early embryonic stage of development; it subsequently divides into the urogenital sinus and the terminal part of the rectum, which have separate urogenital and anal openings. In amphibians the urinary bladder is formed from an evagination of the abdominal wall of the cloaca. Allantoides appear in the embryo of amniotes.