View source for Raphidiophrys contractilis

{{Short description|Species of single-celled organism}}
{{Taxobox
| image = Raphidiophrys contractilis.jpg
| image_caption = ''Raphidiophrys contractilis''
| domain = [[Eukaryota]]
| classis =
| ordo = [[Centrohelida]]
| familia = [[Raphidiophryidae]]
| genus = [[Raphidiophrys]]
| species = '''''R. contractilis'''''
| binomial = '''''Raphidiophrys contractilis'''''
| binomial_authority =
| subdivision_ranks = Subspecies
| subdivision =
}}
'''''Raphidiophrys contractilis''''' is a species of freshwater [[centrohelid]].
==Discovery==
This species was first isolated from a brackish pond in [[Shukkei-en|Shukkeien Garden]], Naka-ku, Hiroshima City, [[Japan]].<ref name="Kinoshita1995">{{cite journal | last1 = Kinoshita | first1 = Eiji | last2 = Suzaki | first2 = Toshinobu | last3 = Shigenaka | first3 = Yoshinobu | last4 = Sugiyama | first4 = Masanori | title = Ultrastructure and Rapid Axopodial Contraction of a Heliozoa, ''Raphidiophrys contractilis'' Sp. Nov. | journal = The Journal of Eukaryotic Microbiology | volume = 42 | issue = 3 | year = 1995 | pages = 283–288 | issn = 1066-5234 | doi = 10.1111/j.1550-7408.1995.tb01581.x}}</ref>
==Description==
''Raphidiophrys contractilis'' is a spherical organism measuring between 7 and 19&nbsp;μm in diameter and has several [[pseudopodia#axopodia|axopodia]] measuring between 60 and 110&nbsp;μm. The axopodia are sustained by a set of [[microtubule]]s arranged in a complex of hexagons and triangles.<ref name="Kinoshita1995" /> The cell body is coated by a thin layer of small scales composed of [[silica]]. These scales are oblong, with curved edges and with the surface always facing the cell body.<ref name="Kinoshita1995" />
==Feeding behavior==
''Raphidiophrys contractilis'' preys on other protists, such as flagellates and ciliates, and captures them with its axopodia. The axopodia contain many organelles called kinetocysts, which are released on the prey's surface and probably have a paralyzing effect.<ref name="Sakaguchi2002">{{cite journal | last1 = Sakaguchi | first1 = Miako | last2 = Suzaki | first2 = Toshinobu | last3 = Mostafa Kamal Khan | first3 = S.M. | last4 = Hausmann | first4 = Klaus | title = Food capture by kinetocysts in the heliozoon ''Raphidiophrys contractilis'' | journal = European Journal of Protistology | volume = 37 | issue = 4 | year = 2002 | pages = 453–458 | issn = 0932-4739 | doi = 10.1078/0932-4739-00847}}</ref> After the prey is attached to the axopodium, the axopodium contracts rapidly, at a velocity of about 1&nbsp;mm/s, this being the reason for the species being named ''Raphidiophrys contractilis''.<ref name="Kinoshita1995" />
Although ''R. contractilis'' is not a colonial species, several individuals can cooperate in the capture of larger prey. In this case, the individuals gather around the prey and fuse into a larger structure with partially joined cytoplasms and build a common food vacuole to ingest and digest the prey organism.<ref name="Sakaguchi2002" />
==References==
{{reflist}}
==External links==
*[https://earthlingnature.wordpress.com/2019/03/29/friday-fellow-contractile-gentle-scaled-centrohelid/ Friday Fellow: Contractile Gentle-Scaled Centrohelid] at Earthling Nature.
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[[Category:Haptista]]
{{Hacrobia-stub}}