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Phylum Hexapoda Coloniales Lyrics: Shin Kubota, Music and Vocal: Juri Goto |
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At a glance, entoprocts look like hydrozoans in the phylum Cnidaria. Entoprocts attaches to the surface of rocks or shells on the sea floor and normally live a colonial life. Some species are solitary and may attach to the body of various invertebrates. The solitary species can move around like leeches. One unit of colonial Entoplacta consists of a flower-like main body (calix), a stalk which supports calix, and a stolon which attaches to other objects. The stalk and stolon are covered with a thin layer of chitinous substance. Characteristics of the stalk are important keys to the taxonomic identification. This one unit, a zooid, is very small, about one mm in length. Many zooids bud from many parts of the stolon. As a whole, one colony is about a few cm in diameter. If you touch any of the zooids, they synchronize to twist the body from the bottom of the stalks all over the places. They rhythmically repeat the movement quickly. Because such movement looks like swinging a lot of tiny bells, a certain species is called the bell sea-moss in Japan. Moreover, because of their unique movements, this phylum may also be called the Kamptzoa meaning bent or curved animals. As just described, entoprocts can move quickly, and it is easy to distinguish entoprocts from hydrozoans. Furthermore, the tentacles of the Entoprocta have cilia but no nematocysts, and a stimulus cause the tentacles, together with the calyx, to fold inward without shrinking to a small lump. These characteristics are different from those of the hydrozoa as well. Inside of the body clearly is bilateral symmetry which is also a major difference from radial symmetry of the hydrozoan body. The digestive tract runs through the inside of flower-like calyx. The mouth is located at an upper part of the calyx and the anus is also located another area of the upper calyx, and the digestive tract is U-shaped. Several tens of the ciliated tentacles generate water flow to collect small organic particles and microbial plankton and eat them. The water flow is generated from the base to the tip of the tentacles. There is no hollow space inside of the body, and the heart and blood circulatory systems are absent. However, the simple nervous system is present. The brain is not differentiated, but the ganglion is present as a nerve center. An individual of the Entoprocta is either hermaphroditic or gonochroic. Internally fertilized eggs may grow to the embryos in the brood pouch located at the top of the calyx. Many different types of embryos exist, and one of them is a planktonic larva which is similar to the trochophore larvae of the Annelid and the Mollusca. About 150 species of the Entoprocta, such as the order Coloniales, inhabit on the seafloor of the world ocean. Of those, only about 30 species are known to exist in Japan. As a minority, a few species of the Entoprocta, such as Urnatella gracilis, live in freshwater. In general, freshwater organisms do not produce planktonic larvae; however, Urnatella gracilis is well known to produce strange looking larvae. Due to the simple body structure, the Entoprocta is considered as a low order animal. However, the phylogenic relationship is unclear. |
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Bell swing dances Coloniales |
I am sorry.
A song is only Japanese.
Song
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karaoke
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