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Phylum Phoronida Phoronis Lyrics: Shin Kubota, Music, Vocal and Arrangement: Sillty |
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Not many people have actually seen a phoronid. There are only 13 species of the Phoronida; and therefore, they are in a minor taxonomic group. All the species live on the sea floor, and all of them live calmly eating organic debris and small plankton. Only two species of the Phoronida are found in Japan. The Phoronida builds a tube from a glue-like substance as a nest to protect the soft body. Some species of the Phoronida attach to tubes built by tube dwelling anemones which belong to the Cnidaria. Some large size phoronids may reach 50 cm long, but most of them are normally less than 10 cm. The outer shape of the Phoronida looks very similar to a feather duster worm in the Phylum Annelida, and people may misidentify them. The Phoronida has an earthworm-like body, and the lophophore, which looks like bushy tentacles, is located on the anterior end. In Japan, the Phoronida is called the bloom worm because the lophophore looks like a bloom. The lophophore can be regenerated if it is removed. Thus, it is a tough organ. Every tentacle is densely covered with cilia which generate water flow, and the Phoronida use them to collect small organic particles and other materials for nutrients. A phoronid has as many as 500 tentacles. The mouth opens wide as if it is split open in the lophophore. The anus is not located at the posterior end of the body but right next to the lophophore. Not in there, but it opens toward outside. The trunk is long and slender like that of a feather duster worm. However, unlike feather duster worms, phoronids do not have body segments. Therefore it is easy to distinguish these two animals. The Phoronida has only three body segments. There is a U-shaped digestive tract in the trunk. There are well developed ovary and testicle in the trunk, and many species are hermaphroditic. There is no organ equivalent to a heart, but the closed blood vascular system is present and transparent blood circulates in the body, and the blood cells contain hemoglobin. All the uniquely shaped larvae of this phylum live planktonic life. In 1846, J. Mueller discovered these larvae during plankton sampling, and he described them as a new species and named the genera as Actinotrocha. This name becomes the name of all the Phoronida larvae today. The parent-larva relationship of the Phoronida was discovered 20 years later. The actinotrocha larvae are small, approximately a few mm long. The outer shape looks similar to Melibe, a nudibranch belonging to the phylum Mollusca. The head part of the actinotrocha larva has a preoral lobe which looks like a snap lock purse. The tentacles make a loop around the preoral lobe. The larvae stick the preoral lobe into the sand or mud on the sea bottom and reverse the inner part of the body and extend the long and slender trunk into the sand deeper and deeper to reach the end of the transformation. This transformation can be observed in a petri dish. It takes only several hours to complete this transformation show. |
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Looking like feather duster worms, The Phoronid |
I am sorry.
A song is only Japanese.
Song
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Copyright (C); 2007, Shin Kubota.All Rights Reserved.