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Priapulida
*** Shopping-Tip: Priapulida
{{Taxobox
| color = pink
| name = Priapulida
| regnum =
Animalia
| phylum = '''Priapulida'''
| phylum_authority = Théel, 1906
}}
'''Priapulida''' ('''priapulid worms''' or '''penis worms''') are a
Phylum (biology) phylum of marine
worms with an extensible spiny
proboscis. Priapulid fossils are known at least as far back as the Middle
Cambrian. Their nearest relatives are probably
Kinorhyncha and
Loricifera with which they constitute the taxon
Scalidophora. They were likely the major predators of the Cambrian period.
''(from
1911 Encyclopædia Britannica)''
They are cylindrical worm-like animals, with a median anterior mouth quite devoid of any armature or tentacles. The body is ringed, and often has circles of spines, which are confinued into the slightly protrusible pharynx. The
alimentary canal is straight, the anus terminal, though in ''Priapulus'' one or two hollow ventral diverticula of the body-wall stretch out behind it. The nervous system, composed of a ring and a ventral cord, retains its primitive connection with the ectoderm.
There are no specialized sense-organs or vascular or respiratory systems (
hemerythrin is the protein responsible for oxygen transportation). There is a wide body-cavity, but as this has no connection with the renal or reproductive organs it cannot be regarded as a coelom, but probably is a blood-space or haemocoel.
The Priapuloidea are dioecious, and their male and female organs, which are one with the excretory organs, consist of a pair of branching tufts, each of which opens to the exterior on one side of the anus.
The tips of these tufts enclose a flame-cell similar to those found in
Platyhelminthes, etc., and these probably function as excretory organs. As the animals become adult, diverticula arise on the tubes of these organs, which develop either spermatozoa or ova. These pass out through the ducts. Nothing is known of the development. There are three genera: (i.) ''Priapulus'', with the species ''P. caudatus'' Lam. of the Arctic Mouth, surrounded by spines,and Antarctic and neighboring cold seas, and ''P. bicaudatus'', Dan., of the north Atlantic and Arctic seas; (ii.) ''Priapuloides australis'', de Guerne, of the southern circumpolar waters; and (iii.) ''Halicryptus'', with the species ''H. spinulosus'', v. Sieb., of northern seas. They live in the mud, which they eat, in comparatively shallow waters up to 50
fathoms (90 m).
Apel, Zeitschr. wiss. Zool. (1885), vol xlii.; Scharif, Quart. foam. Mic. Sd. (i885), vol. xxv.; Ehlers, Zeitschr. wiss. Zool. (i86i), vol. xi.; Schauinsland, Zool. Anz. (i886), vol. ix.; J. De Guerne, ''Mission scientifique du Cap Horn'' (1891), vol vi.; Michaelsen, Jahrb. Hamburg-A fist. (i888), vol. vi.
References
*{{1911}}
Category:Animals
{{Link FA|de}}
Classification
Phylum Priapulida
Genus †Ancalagon
Genus †Anningvermis
Genus †Corynetis
Genus †Ottoia
Class Priapulimorpha
Order Priapulimorphida
Family Priapulidae
Genus Acanthopriapulus
Genus Priapulopsis
Genus Priapulus
Family Tubiluchidae
Genus Meiopriapulus
Genus Tubiluchus
Class Halicryptomorpha
Order Halicryptomorphida
Family Halicryptidae
Genus Halicryptus
Class Seticoronaria
Order Seticoronarida
Family Maccabeidae
Genus Maccabeus
cs:Hlavatci
de:Priapswürmer
fr:Priapula
it:Priapulida
pl:Niezmogowce
pt:Priapulida
fi:Makkaramadot
zh:鳃曳动物门
*** Shopping-Tip: Priapulida
