Tailed priap worm
| Tailed priap worm | ||||||||||||
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Priapulus caudatus from the intertidal zone of the Barents Sea - introvert above, tail with papillae below right |
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| Scientific name | ||||||||||||
| Priapulus caudatus | ||||||||||||
| Lamarck , 1816 |
The tailed priap worm or common priap worm ( Priapulus caudatus ) is a species of priapula worms from the family Priapulidae that lives in sand and silt in arctic waters.
features
The cylindrical, flesh-colored body of Priapulus caudatus is divided into introvert (proboscis or proboscis ), trunk (trunk) and tail and is about 2 to 7.5 cm long. In the middle, the trunk is about 5 to 10 mm thick.
The mouth at the very front is surrounded by 7 rings of 5 teeth each. The introvert, the retractable front section of the worm, which is slightly thickened towards the front, makes up about a fifth to a third of the body length. It has 25 longitudinal ribs that are covered with small sharp points. The transverse muscles under the skin shine through from the inside as horizontal stripes. The trunk is separated from the trunk by a constriction and has about 37 to 40 body rings separated from one another by strong furrows, under which the circular muscles lie and which become indistinct towards the end of the body. On each of these rings there are small spikes at irregular intervals. At the warty end of the trunk is the approximately 1 mm long anus and a little in front of it on both sides the genital orifices. On the abdominal side of the anus, at the end of the trunk, sits the tail with its numerous tentacle-like processes, about 1 mm thick and up to 6 mm long, called papillae. When contracted, both the anus and the base of the tail are covered by swelling of the body. The nerve cord running from the pharyngeal nerve ring is visible on the abdomen as a white shimmering stripe. The intestine runs in a straight line from the mouth to the anus. It consists of a short, muscular pharynx (about 4 mm with a total of 36 mm long intestine), a dark midgut (about 21 mm) and a significantly thinner, translucent rectum (about 11 mm). The proboscis is pulled back by 8 pulling muscles of equal length.
Distribution and occurrence
The common priap worm can be found circumboreally in colder waters of the northern hemisphere. The sites include Greenland , the Shetland Islands , Leith (Devon, England ) and Belfast ( Ireland ) as well as the Barents Sea . It lives in clay or sandy soil in the intertidal zone and below. With the proboscis, he digs a body-length cave that can be recognized by the piles of ejected substrate.
nutrition
The diet of Priapulus caudatus has repeatedly been controversial. Feeding experiments as well as investigations of the intestinal contents indicate that it is an omnivore that eats carrion, worms and algae. Among the of Priapulus caudate eaten animals include brittle stars and polychaete , including Aphrodita spp.
Life cycle
Priapulus caudatus is separate sexes with males and females of equal size. The gametes are released into the sea water, where fertilization takes place. It develop at loricifera reminiscent Lorica - larvae that live in the sediment and probably feed on detritus. It takes about 2 years to develop into a fully grown worm.
Surname
As early as 1758, Carl von Linné used the name Priapus humanus as a name for the priapus worm he described, which strongly reminds him of a human penis , but added the species Priapus equinus to the genus , which means that it is the horse actina (today's name Actinia equina ), i.e. a cnidarians . Linnaeus took the generic name Priapus on the Greek god of male fertility Priapus reference that is represented by a gigantic erect penis. In Latin, Priapus also simply means “stiff penis” (similar to phallus , both Greek loan words). Thus, the two species names given by Linné stood for “human penis” (priap worm) and “horse penis” (horse action line). In 1767 Linnaeus used the name Holothuria priapus for the "penis worm" , so he saw it as a sea cucumber . In 1816, Jean-Baptiste de Lamarck used the diminutive Priapulus , "small stiff penis", in his description and added as a specific epithet caudatus , "tailed", referring to the conspicuous tail . Due to the ambiguity in the assignment of Linnaeus 'description to two or three completely different animals, Lamarck's name prevailed, and although Linnaeus' name is the older, it is rejected by a decision of the International Commission for Zoological Nomenclature (ICZN).
literature
- E. Ehlers: About the genus Priapulus Lam. A Contribution to Knowledge of the Gephyreen. With panel XX. XXI. Journal of Scientific Zoology, Volume 11. Wilhelm Engelmann, Leipzig 1862. pp. 205-252.
- JD Fish, S. Fish: A Student's Guide to the Seashore. Cambridge University Press, Cambridge 2011. p. 140.
Web links
- MJ de Kluijver et al .: Priapulus caudatus Lamarck, 1816. Marine Species Identification Portal
Individual evidence
- ↑ Tom Trott (1998): Gustatory responses of Priapulus caudatus de Lamarck, 1816 (Priapulida, Priapulidae): Feeding behavior and chemoreception by a living fossil. Marine and Freshwater Behavior and Physiology 31 (4), pp. 251-257.
- ^ Sofia A Wennberg, Ralf Janssen, Graham Budd (2009): Hatching and earliest larval stages of the priapulid worm Priapulus caudatus. Invertebrate Biology 128 (2), pp. 157-171. DOI 10.1111 / j.1744-7410.2008.00162.x
- ^ Johann Peter Eberhard: Attempt of a new draft of the animal history. With an appendix of some rare and as yet little described animals. Renger, 1768. §6. The human Priapus from the North Sea (Priapus humanus). P. 277.
- ^ Daphne G. Fautin (2013): Hexacorallians of the World. Priapus humanus Linnaeus, 1758. World Register of Marine Species, accessed May 16, 2018.
- ^ B. Neuhaus (2018): World List of Priapulida. Priapulus caudatus Lamarck, 1816. World Register of Marine Species, accessed May 16, 2018.