|
|
 |
Phylum Nematomorpha Horsehair worms Lyrics: Shin Kubota, Music and Vocal: Juri Goto |
 |
||
|
The Nematomorpha is commonly known as horsehair worms. This phylum is similar to the Nematoda and sometimes called the Gordeacea. Parasitic when they are young, normally in terrestrial insects, such as praying mantis, or in myriapods, such as centipedes or millipedes. Nematomorphs stay in the host’s body and absorb nutrient from the body surface. Thus, the digestive organ is present but regressed, the intestine is discontinued in the middle, and The remains is merely a trace. Moreover, there is no mouth or anus. In addition, there are no excretory, circulatory or respiratory systems and no segmented bodies. The body length of the Nematomorpha reaches to 1 m long, but the diameter is only few mm. In the past, nematomorphs are found in water buckets for horses and people used to believe that nematomorphs emerge from the horse hair. Thus, they are called horsehair worms. One of the nematomorphs’ characteristics is complex coiling of their body. At a time in the past, Gordian king tied an intricate knot and declared “whomever untied the knot should rule the small Asia”. Alexander the Great cut the intricate Gordian knot with his sword and solved the problem. And the Nematomorpha is named after this legend and also called Gordian worms. Horsehair worms sexually reproduce in water. Once in the water, horsehair worms crawl or swim like serpentine motion. The males move around well to find less mobile females. Copulation is done by the male tangling female and ejaculating sperms in the sperm receptor in the posterior end of the female body. The males die soon after ejaculation. After the copulation, the females lay gelatinous strings filled with several million fertilized eggs by hooking on plants in fresh water. A fertilized egg goes thorough spiral cleavage to advance development. In due time, the fertilized egg grows to the juvenile in half a month to a few months and hatches. The juvenile has the retractable proboscis in and out of the body. At a glance, its morphology looks like that of the Kinorhyncha. Furthermore, the transverse section of the proboscis is penta-radially symmetrical, and thus, it is presumed that the Nematomorpha is closely related to the Kinorhyncha. The juvenile is a few tens of micrometers in length, hence very small. The juvenile becomes parasitic in aquatic arthropods, leeches or snails by boring in their bodies with using the proboscis. Afterward, the juvenile horsehair worms change their hosts through the food chain to the final hosts, e.g. insects such as praying mantis, beetles, grass hopper, crickets, and cockroaches as well as polychaetes and eventually become adults. The adults completely lose the proboscis, and the body extends long and thin. By chance, in a rare instance, a horsehair worm entered into a human child. Horsehair worms distribute around the world and 275 species are known. None of them have colorful bodies. Normally, they are terrestrial, but a few species on the coasts of the Malay Archipelago, the Gulf of Naples, Norwegian coasts, the east coast of North America and so on are marine species. The larvae of Nectonema (swimming horsehair worm) first enter into crustaceans such as crabs and hermit crabs in the sea. It is believed that before long they metamorphose in these hosts and live planktonic life as they mature in the sea. However, the details of their life history are still unclear. Swimming horsehair worms have bristles all around the body except the front and rear ends. The body length is less than 20 cm, but the body diameter is less than 1 mm and very thin. They are not found in Japan yet, but the discovery is anticipated in the future. |
|
The horsehair worm is 1 meter long, 3 mm in diameter |
I am sorry.
A song is only Japanese.
Song
|
|
karaoke
|
|
Copyright (C); 2007, Shin Kubota.All Rights Reserved.