The corallimorpharian Paracorynactis hoplites feeds on the sea star Choriaster granulatus in the western Indian ocean

Abstract

Paracorynactis hoplites is a highly efficient predator of various echinoderms and other invertebrates, including large individuals of Acanthaster planci (Bos et al. 2008, 2011). Although this corallimorpharian is usually hiding underneath ledges and inside crevices, individuals have been found in scattered groups on shallow reefs (Bos et al. 2011), suggesting that more individuals may be found in Nacala Bay. The present observation constitutes the first accurate record of P. hoplites from Mozambique and the western Indian Ocean.

Full text

OCEANARIUM
The corallimorpharian Paracorynactis hoplites feeds on the sea
star Choriaster granulatus in the western Indian ocean
Julien Wickel
1
&Mathieu Pinault
1,2
&Remi Garnier
3
&Arthur R. Bos
4,5
Received: 30 November 2015 / Revised: 8 February 2016 /Accepted: 10 February 2016
#Senckenberg Gesellschaft für Naturforschung and Springer-Verlag Berlin Heidelberg 2016
Paracorynactis hoplites (Haddon and Shackleton 1893)
(Anthozoa: Corallimorphidae) was recently assigned to the
new monotypic genus Paracorynactis based on specimens
from Indonesia and observations in the Philippines (Ocaña
et al. 2010). Shortly after, this species was reported from the
western Indian Ocean without locality data (Den Hartog and
Ocaña 2011), whereas earlier a resembling species,
Pseudocorynactis globulifera (Ehrenberg, 1834), was ob-
served on coral reefs off the Seychelles, also in the western
Indian Ocean (Den Hartog 1994).
Paracorynactis can be separated from Pseudocorynactis
by the presence of prominent acrospheres containing unusual-
ly large nematocysts, tentacles with limited extension capabil-
ity, and a highly protractible column (Ocaña et al. 2010;Bos
et al. 2011). The maximum number of tentacles in adults may
provide an additional diagnostic character (Ocaña et al. 2010):
<180 in Paracorynactis and <115 in Pseudocorynactis.In
contrast to most other corallimorpharians that occur in aggre-
gations and apply camouflage or mimicry (e.g. Waheed and
Hoeksema 2012), P. hoplites individuals usually hide in crev-
ices as solitary predators lurking for prey (Bos et al. 2011).
An individual of P. hoplites was observed feeding on a sea
star, Choriaster granulatus Lütken 1869, during a survey in
Nacala Bay (14°27′09″S; 40°40′39″E), Mozambique in
June 2014 (Fig. 1a). The corallimorpharian was attached un-
derneath a ledge at 4 m depth and had protracted its column in
order to connect its acrospheres to the sea star’s upper surface.
Once one of the prey’sarmswasengulfedbythe
corallimorpharian’s mouth, the acrospheres released the prey
while uncovering whitened skin (Fig. 1b). A consolidated
substrate may have provided traction to the sea star, allowing
it to escape.
Paracorynactis hoplites is a highly efficient predator of
various echinoderms and other invertebrates, including large
individuals of Acanthaster planci (Bos et al. 2008,2011).
Although this corallimorpharian is usually hiding underneath
ledges and inside crevices, individuals have been found in
scattered groups on shallow reefs (Bos et al. 2011), suggesting
Communicated by B. W. Hoeksema
*Julien Wickel
julien.wickel@gmail.com
1
Marex -Marine Expertise Company, 13 Chemin Camille Roche,
97425 Les Avirons, Reunion Island, France
2
UMR 9220 UR-CNRS-IRD - Entropie, University of Reunion,
Saint-Denis, Reunion Island, France
3
Pareto, Saint-Denis, Reunion Island, France
4
Department of Biology, American University in Cairo, Cairo, Egypt
5
Naturalis Biodiversity Centre, Leiden, The Netherlands
Mar Biodiv
DOI 10.1007/s12526-016-0461-x

that more individuals may be found in Nacala Bay. The
present observation constitutes the first accurate record
of P. hoplites from Mozambique and the western Indian
Ocean.
References
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Fig. 1 Paracorynactis hoplites in Nacala Bay, Mozambique. aPolyp
extending from underneath a reef ledge capturing a seastar, Choriaster
granulatus. bTraces of the predator’s acrospheres remaining on the
prey’suppersurface
Mar Biodiv