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Foronis

Müller 1846 \n* ''Phoronella'' Haeckel 1896 "}},"i":0}}]}"> Phoronis es uno de los dos géneros de la familia de gusanos herradura ( Phoronidae ), en el filo Phoronida . El cuerp...

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Phoronis es uno de los dos géneros de la familia de gusanos herradura ( Phoronidae ), en el filo Phoronida . El cuerpo tiene dos secciones, cada una con su propio celoma . Hay una estructura de alimentación especializada, el lofóforo , que es una extensión de la pared del celoma y está rodeado de tentáculos. El intestino tiene forma de U. La característica diagnóstica que distingue a este género es la falta de invaginación epidérmica en la base del lofóforo. Estos gusanos son filtradores . [ 1 ] Viven en sustratos duros o sedimentos blandos en ambientes marinos de todo el mundo. [ 2 ] Tienen diferentes modos de reproducción que ayudan a su éxito.

El nombre científico de la forma larvaria es Actinotrocha .

Etimología

El nombre genérico hace referencia a Phoronis (más conocida como Io), un personaje de la mitología griega que a veces se confunde con Isis . [ 3 ] Thomas Strethill Wright, de Edimburgo, no dio una razón específica para elegir el nombre. [ 4 ]

Especies

Phoronis architecta ya no se acepta y se considera sinónimo de Phoronis psammophila . De manera similar, Phoronis vancouverensis se considera sinónimo de Phoronis ijimai . [ 6 ]

Un análisis filogenético de 2018 indica que Phoronis es parafilético , mientras que Phoronopsis es un género monofilético. [ 7 ]

Distribución

Horseshoe worms are not very sensitive to environmental conditions and are therefore considered to be both eurythermic and euryhaline animals. While they are not very sensitive, there are some factors that can impact their distribution such as current strength (as they are filter feeders), the result of asexual reproduction, predation in the area, and local fauna which they may have to compete with. However, horseshoe worms have a relatively global distribution as they can be found in the Atlantic, Pacific, and Indian oceans.[8]

Structure

Tube

The horseshoe worms live in tubes that are fully imbedded in the soil and are formed during digging or boring. The tubes are produced by the worm's epidermal glands. These tubes have an inner organic cylinder and an outer layer. The inner layer is composed of three parts: the inner film, middle film, and outer film. These thin films are composed of fibers from the worms that form nets that make up these tubes.[2]

Nervous and digestive systems

These worms have a nervous system that consists of a dorsal ganglion, a tentacle nerve ring, an inner nerve ring, intertentacular groups of perikarya, and tentacle nerves. These tentacles nerves have three groups: abfrontal, frontal, and laterofrontal.[9] They have a U-shaped gut, meaning their anus is close in distance to their mouths and their digestive tract consists of three parts: the mouth, the stomach, and the anus.[10][11]

Lophophore

The lophophore structure has evolved from a simple, oval shape to the horseshoe shape from which the worms get their name, even into a complex spiral structure.[12] These worms can regenerate their lophophores when injured or even voluntarily drop their lophophores as Phoronis ovalis does when it is laying eggs.[10] The lophophore is used for both respiration and feeding. The tentacles of the lophophores have cilia on them which move water towards their mouth to filter out small particulates.[8][10][11] Through moving water over the tentacles of the lophophore, they act as an organ for gas exchange and allow oxygen into the blood as it passes through.[10][11]

Development

Embryos

Generally, Phoronis species have benthic adults with lecithotrophic larvae. These species incubate their embryos in various ways. Some species release their embryos into the water column and they develop there. In other species, embryos are incubated among the tentacles of the adult worms. Recently, it was discovered that some species even exhibit viviparity, where the embryos are incubated in the coelom of their mother's tube and the "hatch" to produce feeding actinotroch larvae. There is a correlation between egg size and development type: allowing embryos into the water column to develop takes less energy and can therefore produce more eggs. Incubating in the tube's coelom takes more energy so less eggs are produced.[2]

Larvae

The lecithotrophic larvae, given the name actinotroch, are pelagic and float in the water column. This allows for wider dispersal of species. The larvae have also developed different morphologies over time such as differing pigmentation and arrangement of blood masses.[13]

Adult

When they are full grown, these worms typically have thin but long bodies that can grow up to 50 cm. The adults are typically colonial and can grow around each other in order to support each other.[10]

Reproduction

Phoronis can be either gonochoristic or hermaphroditic. The worms create sperm and eggs through the processes of spermiogenesis and oogenesis. Spermiogenesis leads to the creation of a spermatophore, which is inserted into the metacoelom to combine with the eggs in two ways. The small fertilized eggs, numbering up to 500, are then released through spawning into the water column where the larvae develop over a period of 3 weeks before settling to change into the adult stage.[8][10] Others lay fewer, larger eggs, and after fertilization, do not release them until they have hatched. These larvae are only in the water column for a period of 4 days before settling to find their home.[10][11]

Parasite

Some phoronid species have microsporidia-like spores that were discovered in 2017.[14] This was the first recorded instance of phoronids being hosts to parasites. These microsporidia were named Microsporidium phoronidi.

References

  1. ↑"Phoronida". Archived from the original on 2012-03-23. Retrieved 2011-08-13.
  2. 1 2 3 Temereva, Elena; Shcherbakova, Tatiana; Tzetlin , Alexander (2020-12-01). "Primeros datos sobre la estructura de los tubos formados por foronídeos" . Zoología . 143 125849. doi : 10.1016/j.zool.2020.125849 . ISSN 0944-2006 . PMID 33099239. S2CID 224887177 .   
  3. ↑ "Phoronis" . Diccionario Merriam-Webster.com . Merriam-Webster. OCLC 1032680871 . "Latín neolatino, probablemente del latín Phoronis ( Io , sacerdotisa mítica de Argos amada por Zeus)".
  4. ↑ Strethill Wright, T. (1856). "Descripción de dos animales tubícolas" . The Edinburgh New Philosophical Journal . 4 (nueva serie). Edimburgo: 316. [La nota al pie completa:] Phoronis, uno de los apellidos de Isis .
  5. ↑ Registro Mundial de Especies Marinas
  6. ↑ ITIS
  7. ↑ Temereva, EN; Neklyudov, BV (2018). Una nueva especie de forónido, Phoronis savinkini sp. n., del Mar de China Meridional y un análisis de la diversidad taxonómica de Phoronida. Biology Bulletin . 45(7): 617-639. doi : 10.1134/s1062359018070154
  8. 1 2 3 Emig, C. (1982). "La biología de los foronídeos" (PDF) . Biología marina avanzada . Avances en biología marina. 19 : 1–89 . doi : 10.1016/S0065-2881(08)60086-3 . ISBN 978-0-12-026119-2.
  9. ^ Temereva, Elena N. (1 de diciembre de 2020). "Nuevos datos sobre la inervación del lofóforo en forónidos adultos (Lophophorata, Phoronida)" . Zoología . 143 125832. doi : 10.1016/j.zool.2020.125832 . ISSN 0944-2006 . PMID 32971479 . S2CID 221915433 .   
  10. 1 2 3 4 5 6 7 profesor, Gordon RamelGordon es un ecólogo con dos títulos de la Universidad de Exeter. También es un; Poeta, A.; de 1, El propietario; Oh -, 152 libros; Sitio web, Él escribió esto (2020-03-04). "Filo Phoronida (Los gusanos herradura)" . Earth Life . Recuperado el 2021-04-06 .{{cite web}}: CS1 maint: nombres numéricos: lista de autores ( enlace )
  11. 1 2 3 4 "Phoronida" . ResearchGate . Consultado el 6 de abril de 2021 .
  12. ↑ Temereva, Elena N. (diciembre de 2019). "Mioanatomía del lofóforo en foronídeos adultos y la evolución del lofóforo de los foronídeos" . The Biological Bulletin . 237 (3): 270– 282. doi : 10.1086/705424 . ISSN 0006-3185 . PMID 31922911. S2CID 210149341 .   
  13. ↑ Collin, Rachel; Venera-Pontón, Dagoberto E.; Driskell, Amy C.; Macdonald, Kenneth S.; Chan, Kit-Yu Karen; Boyle, Michael J. (2019). "Documentando la diversidad neotropical de foronídeos con código de barras de ADN de larvas planctónicas" . Invertebrate Biology . 138 (2) e12242. doi : 10.1111/ivb.12242 . hdl : 10088/97712 . ISSN 1744-7410 . 
  14. ↑ Temereva, Elena N.; Sokolova, Yuliya Y. (2018). "Una infección por microsporidios en foronídeos (filo Phoronida): Microsporidium phoronidi n. sp. de un Phoronis embryolabi" . Journal of Eukaryotic Microbiology . 65 (3): 427– 431. doi : 10.1111/jeu.12490 . ISSN 1550-7408 . PMID 29171125. S2CID 19074226 .