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In the English language, many animals have different names depending on whether they are male, female, young, domesticated, or in groups. The best-known source of many English words used for collective groupings of animals is The Book of Saint Albans , an essay on hunting published in 1486 and attributed to Juliana Berners . [ 1 ]
About 3,000 species of tunicate exist in the world's oceans, living mostly in shallow water. The most numerous group is the ascidians; fewer than 100 species of these are found at depths greater than 200 m (660 ft). [12] Some are solitary animals leading a sessile existence attached to the seabed, but others are colonial and a few are pelagic.
The smallest of the three groups of tunicates is the Appendicularia. They retain tadpole-like shapes and active swimming all their lives, and were for a long time regarded as larvae of the other two groups. [29] The other two groups, the sea squirts and the salps, metamorphize into adult forms which lose the notochord, nerve cord, and post anal ...
1. Narwhals. Narwhals are known as the "unicorns of the sea" due to their long, spiral-like tusks, which are actually elongated teeth. These mysterious marine mammals inhabit Arctic waters and use ...
Trish Khan, the Milwaukee County Zoo's curator of primates and small mammals, has worked at the zoo for more than 30 years, and in that time, methods for naming animals have changed. "It used to ...
The lancelet notochord, unlike the vertebrate spine, extends into the head. This gives the subphylum, Cephalochordata, its name (κεφαλή, kephalē means 'head'). The fine structure of the notochord and the cellular basis of its adult growth are best known for the Bahamas lancelet, Asymmetron lucayanum [51]
As a general rule, the larva possesses a long tail, containing muscles, a hollow dorsal nerve tube and a notochord, both features clearly indicative of the animal's chordate affinities. One group though, the molgulid ascidians, have evolved tailless species on at least four separate occasions, and even direct development. [8]
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