Priapulida
Priapulida | |
---|---|
Priapulus caudatus | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Subkingdom: | Eumetazoa |
Clade: | ParaHoxozoa |
Clade: | Bilateria |
Clade: | Nephrozoa |
(unranked): | Protostomia |
Superphylum: | Ecdysozoa |
Clade: | Scalidophora |
Phylum: | Priapulida Théel, 1906[2] |
Orders | |
Priapulida (priapulid worms, from Gr. πριάπος, priāpos '
Together with
Priapulid-like fossils are known at least as far back as the Middle Cambrian. They were likely major predators of the Cambrian period. However, crown-group priapulids cannot be recognized until the Carboniferous.[1] 22 extant species of priapulid worms are known, half of them being of meiobenthic size.[10]
Anatomy
Priapulids are cylindrical worm-like animals, ranging from 0.2–0.3[11] to 39 centimetres[12] (0.08–0.12 to 15.35 in) long, with a median anterior mouth quite devoid of any armature or tentacles. The body is divided into a main trunk or abdomen and a somewhat swollen proboscis region ornamented with longitudinal ridges. The body is ringed and often has circles of spines, which are continued into the slightly protrusible pharynx.[3] Family Priapulidae have species with a tail or a pair of caudal appendages. A slender tail or tail filament is also found in family Tubiluchidae. Appendages are absent in the remaining families.[13][14] The body has a chitinous cuticle that is moulted as the animal grows.[15] Members of the family Chaetostephanidae also secretes a gelatinous tube, open in both ends, which they live in.[16]
There is a wide body-cavity, which has no connection with the renal or reproductive organs, so it is not a
The
The
The priapulids are
Reproduction and development
Priapulid development has been reappraised recently because early studies reported abnormal development caused by high temperature of embryo culture. For the species Priapulus caudatus, the 80 µm egg undergoes a total and radial cleavage following a symmetrical and subequal pattern.[22] Development is remarkably slow, with the first cleavage taking place 15 hours after fertilization, gastrulation after several days and hatching of the first 'lorica' larvae after 15 to 20 days.[23] The species Meiopriapulus fijiensis have direct development.[24] In current systematics, they are described as protostomes, despite having a deuterostomic development.[25] Because the group is so ancient, it is assumed the deuterostome condition which appears to be ancestral for bilaterians have been maintained.[26]
Fossil record
Phylogeny
External phylogeny]
Ecdysozoa
>529 mya
Internal phylogeny]
†Archaeopriapulida [paraphyletic]
†Ancalagonida Adrianov & Malakhov 1995
†Markuelia Valkov 1983
†
Palaeoscolecida Conway Morris & Robinson 1986
Kinorhyncha Reinhard 1887 (Spiny crown worms; Mud dragons)
Priapulida
Meiopriapulomorpha
Tubiluchidae
†Paratubiluchus Han et al. 2004
Meiopriapulus Morse 1981
Tubiluchus van der Land 1968
Priapulimorpha
Maccabeidae
Maccabeus Por 1973
Halicryptidae
Halicryptus von Siebold 1849
Priapulidae
†Priapulites Schram 1973
†Xiaoheiqingella Hu 2002
Priapulopsis Koren & Danielssen 1875
Acanthopriapulus van der Land 1970
Priapulus Lamarck 1816
Classification
Ecdysozoa | |
>529 mya |
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Classification
There are 22 known extant species:[30][31]
Phylum Priapulida Théel 1906
- Order HalicryptomorphaSalvini-Plawen 1974 [Adrianov & Malakhov 1995; Salvini-Plawen 1974; Eupriapulida Lemburg, 1999]
- Family HalicryptidaeSalvini-Plawen 1974
- Genus Halicryptus
- Species H. higginsi (Shirley & Storch, 1999)
- Species H. spinulosus (von Siebold, 1849)
- Genus Halicryptus
- Family
- Order Meiopriapulomorpha
- Family Meiopriapulidae
- Genus Meiopriapulus
- Species M. fijiensis (Morse, 1981)
- Genus Meiopriapulus
- Family Meiopriapulidae
- Order Priapulomorpha Adrianov & Malakhov 1995 (assigned its own order by [32])
- Family Priapulidae Gosse 1855 [Xiaoheiqingidae (sic) Hu 2002]
- Genus Acanthopriapulus
- Species A. horridus (Théel, 1911)
- Genus Priapulopsis
- Species P. australis (de Guerne, 1886)
- Species P. bicaudatus (Danielssen, 1869)
- Species P. cnidephorus (Salvini-Plawen, 1973)
- Genus Priapulus
- Species P. abyssorum (Menzies, 1959)
- Species P. caudatus (Lamarck, 1816)
- Species P. tuberculatospinosus (Baird, 1868)
- Genus Acanthopriapulus
- Family Tubiluchidae van der Land 1970 [Meiopriapulidae Adrianov & Malakhov 1995]
- Genus Tubiluchus
- Species T. arcticus (Adrianov, Malakhov, Tchesunov & Tzetlin, 1989)
- Species T. australensis (van der Land, 1985)
- Species T. corallicola (van der Land, 1968)
- Species T. lemburgi (Schmidt-Rhaesa, Rothe & Martínez, 2013)
- Species T. pardosi (Scmidt-Rhaesa, Panpeng & Yamasaki, 2017)
- Species T. philippinensis (van der Land, 1985)
- Species T. remanei (van der Land, 1982)
- Species T. soyoae (Scmidt-Rhaesa, Panpeng & Yamasaki, 2017)
- Species T. troglodytes (Todaro & Shirley, 2003)
- Species T. vanuatensis (Adrianov & Malakhov, 1991)
- Genus Tubiluchus
- Family Priapulidae Gosse 1855 [Xiaoheiqingidae (sic) Hu 2002]
- Order Seticoronaria
- Family Chaetostephanidae Por & Bromley 1974 [Chaetostephanidae Salvini-Plawen 1974]
- Genus Maccabeus
- Species M. cirratus (Malakhov, 1979)
- Species M. tentaculatus (Por, 1973)
- Genus Maccabeus
- Family Chaetostephanidae Por & Bromley 1974 [Chaetostephanidae Salvini-Plawen 1974]
Extinct groups
Stem-group †Scalidophora
- Order †Ancalagonida Adrianov & Malakhov 1995 [Fieldiida Adrianov & Malakhov 1995]
- Family †Ancalagonidae Conway Morris 1977
- Genus †AncalagonConway Morris 1977
- Genus †
- Family †Fieldiidae Conway Morris 1977
- Genus †Fieldia Walcott 1912
- Family †Ancalagonidae Conway Morris 1977
Stem-group †Palaeoscolecida
- Family †Selkirkiidae Conway Morris 1977
- Genus †Selkirkia Walcott 1911 non Hemsley 1884
- Order †Ottoiomorpha Adrianov & Malakhov 1995
- Genus †Scolecofurca Conway Morris 1977
- Family †OttoiidaeWalcott 1911
- Genus †Ottoia Walcott 1911
- Family †Corynetidae Huang, Vannier & Chen 2004
- Genus †Corynetis Luo & Hu 1999 [Anningvermis Huang, Vannier & Chen 2004]
- Family †Miskoiidae Walcott 1911
- Genus †MiskoiaWalcott 1911
- Genus †Louisella Conway Morris 1977
- Genus †
References
- ^ S2CID 39772232.
- ^ Théel, Hjalmar (1905–1906). "Northern and Arctic Invertebrates in the Collection of the Swedish State Museum (Riksmuseum). II. Priapulids, Echiurids etc". Kungl. Svenska Vetenskapsakademiens Handlingar. 40 (4): 8–13.
- ^ a b c d e public domain: Shipley, Arthur Everett (1911). "Priapuloidea". In Chisholm, Hugh (ed.). Encyclopædia Britannica. Vol. 22 (11th ed.). Cambridge University Press. p. 313. One or more of the preceding sentences incorporates text from a publication now in the
- S2CID 31342308.
- ^ Cryptic species complex or an incomplete speciation? Phylogeographic analysis reveals an intricate Pleistocene history of Priapulus caudatus Lamarck, 1816
- ^ The phylogeny, classification and zoogeography of the class Priapulida. II. Revision of the family Priapulidae and zoogeography of priapulids
- ISBN 978-0-08-092014-6.
- ^ "Ancestor of arthropods had the mouth of a penis worm".
- S2CID 4397099.
- ISBN 978-3-540-68661-3.
- ISBN 978-3-540-00146-1.
- JSTOR 3227009.
- ^ Tubiluchus lemburgi, a new species of meiobenthic Priapulida
- ^ Kingdoms and Domains: An Illustrated Guide to the Phyla of Life on Earth
- ^ ISBN 978-0-03-056747-6.
- ^ Handbook of Zoology
- ^ ISSN 1432-234X.
- ^ Evidence for Direct Development in Meiopriapulus fijiensis (Priapulida)
- .
- ISBN 978-0-07-302826-2.
- S2CID 84539380.
- S2CID 11175247.
- PMID 19470151.
- JSTOR 3226738.
- PMID 23103190.
- ^ "Penis worms show the evolution of the digestive system".
- ^ doi:10.1130/G30829.1.
- hdl:2381/38663.
- .
- ISBN 978-0-691-17025-1.
- ^ 2019 Annual Checklist : Browse taxonomic classification phylum: Cephalorhyncha, class: Priapulida
- ^ Adrianov A. V, Malakhov V. V. 2001. Symmetry of priapulids (Priapulida). 1. Symmetry of adults. 247:99–110.
External links
- "Evolution of the penis worm". Press Releases. University of Bristol. 2006-08-09.