|
|
 |
Phylum Kinorhyncha Mud dragons Lyrics: Shin Kubota Song and Arrangement: Juri Goto |
 |
||
|
A notable characteristic of the Kinorhyncha is a proboscis with many spines. The transverse section of the proboscis reveals uniquely structured penta-radial symmetry. Unlike Nemertea's proboscis, which is long and flexible like an elastic cord, Kinorhyncha's proboscis looks like a short club. Mud dragons move on the sea floor by inverting the proboscis inside out from the trunk. They catch food as they move. Their foods are diatoms, small organisms and organic matters in the mud. As the name Kinorhyncha (k?ne? = move and rhynchos = snout) suggests, they literally lives by moving their proboscises. In order to live between the sand particles, their tiny body is less than 1 mm in length. All the species of the Kinorhyncha have spines on all over the body, and that is why they are called mud dragons. The body surface is covered with cuticles similar to that of the harpacticoida (phylum Crustacea), and they look like wearing armor. All the Kinorhyncha species are free-living, and they have the mouth, anus, digestive tract and excretory system. They exchange gaseous oxygen and carbon dioxide through the body surface, and thus, they do not have any respiratory system. A notable evolutional feature of the Kinorhyncha is a creation of segments which repeat themselves in regular patterns. All the Kinorhyncha species have a body consisting of a fixed number of segments of 13. Compared to the Annelid, which include earthworms and lugworms, the Kinorhyncha has far less number of segments. Each segment has a repeating structure of ganglion and muscles alternately for locomotion. Unlike higher animals, such as humans, who have neurons on the dorsal side, the Kinorhyncha has a single string of neurons on the ventral side of the body. The muscle of the Kinorhyncha is well-developed, but they only have longitudinal muscles. Many invertebrates have circular muscles, but the Kinorhyncha is not one of them. Kinorhynchans cannot elongate and contract their body, but their movement looks like hopping. This movement is similar to that of round worms. Each individual is either male or female (gonochoric), but the sexual reproduction of the Kinorhyncha is not well-understood. No parasitic species has been found. Many benthic animals produce planktonic larvae which do not look like their adult form, but the mud dragon's larvae look similar to the adult. However, the head part of the larva does not have spines like the adult. The larva molts repeatedly to grow to the adult like crustaceans such as shrimps and crabs. No asexual reproduction has been observed. Kinorhynchans prefer well oxygenated sandy mud bottom the most, and they distribute from the coastal areas to the deep sea. When insufficient decomposition due to eutrophication becomes excessive and the water near the sea bottom becomes hypoxic, kinorhynchans are the first animals to move away to better environment. For this reason, the Kinorhyncha is a useful indicator animal to detect changes in the environment. Globally, not many researchers study this animal, and only 160 species of the Kinorhyncha have been discovered from the world's oceans. The study of the Kinorhyncha is not well advanced in Japan as well. In recent years, at least seven species (including new species) belonging to five genera have been observed in Tanabe Bay, Wakayama Prefecture, Japan (near the Seto Marine Biological Laboratory, Kyoto University). They are yellowish brown color species and no flashy-looking species, but it is possible that many new species of the Kinorhyncha is waiting to be discovered. |
|
The body is all spiny, the mud dragon |
I am sorry.
A song is only Japanese.
Song
|
|
karaoke
|
|
Copyright (C); 2007, Shin Kubota.All Rights Reserved.