Phoronis ijimai Oka, 1897

Larva: Actinotrocha vancouverensis Zimmer, 1964


Phoronis vancouverensis Pixell, 1912

Phoronis savinkini Temereva et Neklyudov, 2017

? Phoronis svetlanae Temereva & Malakhov, 1999

° References of the most recent published diagnoses

Pictures of Phoronis ijimai


Last update: September 9, 2002  

Extended specimens up to 120 mm long, diameter 0.5-2 mm.
Colour in life: fleshy to transparent, lophophore transparent sometimes with white pigment spots.
Lophophore horseshoe-shaped or spiral with about one coil. Up to 230 tentacles, length 2-5 mm.
Nephridia with two funnels (the anal larger than the oral), a single incurved ascending branch; the nephridiopore opens on the nephridial ridge above or at the level of the anus.
Two giant nerve fibre one on the left (diameter: 3-10 µm) and one on the right (diameter: 2-8 µm) occuring at the attachment of the lateral mesenteries to the body wall.
Longitudinal muscle bundles of bushy type; the mean formula and general formula are respectively:

19 | 21
 7 |  7
=54  and  9-31 |12-31
3-13 | 2-13
[32-69]   (n= 294 individuals)

Sexual reproduction hermaphroditic; embryos brooded in two masses by the nidamental glands of A type (i.e., on the floor of the lophophoral concavity and on the inner surface of the internal tentacles); small lophophoral organs.
Asexual reproduction by transverse fission.

Phoronis ijimai is incrusting on hard substrate (rocks, wood, soft substrate) in quiet environments or occasionally burrowing in hard substrate (calcareous rocks and algae, corals...) under water motion. This species extends between the intertidal zone to about 10 m depth.

Phoronis ijimai: the distribution is represented below on the map.

Type-locality: Misaki, Tokyo (Japan)

© Christian C. Emig

Last update: December 28, 2017

Distribution of P. ijimai

  • Most recent published diagnoses

  • Zezina O. N. & S. N. Temereva, 2005. Brachiopoda and Phoronida. In: Biota of the Russian waters of the Sea of Japan, Ed. A. V. Adrianov, vol. 3, 138 p. Dalnauka, Vladivostock.

  • Emig C. C., 2003. Phylum Phoronida. In: Protostomes. Grzimek's Animal Life Encyclopedia, (ed. 2) vol. 2, 491-497.

    Freeman G. & M. Q. Martindale, 2002. The origin of mesoderm in phoronids. Developmental Biology, 252, 301-311.

  • ;Temereva E. N. & V. V. Malakhov, 1999. A new rock dwelling phoronid species, Phoronis svetlanae (Lophophorata, Phoronida) from the Sea of Japan. Zool. Zhurn., 78 (5), 626-630.
  • Emig C. C. & A. Golikov, 1990. On phoronids of the Far Eastern Seas of the USSR and their disribution in the Pacific Ocean (in Russian). Zool. Zh., 69, 22-30.

  • References on Phoronis ijimai

    Phoronis ijimai
    Phoronis ijimai from San Juan Island (Washington State, USA) just below the intertidal zone.
    White dots in the lophophore are embryo masses.

    Copyright Christian C. Emig

    Phoronis ijimai from Los Angeles (California, USA) at 10 m depth.
    White dots in the lophophore are embryo masses.
    Copyright Scott Gietler