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The Feeding, Larval Dispersal, and Metamorphosis of Philippia (Gastropoda: Architectonicidae)

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Title: The Feeding, Larval Dispersal, and Metamorphosis of Philippia (Gastropoda: Architectonicidae)
Authors: Robertson, Robert
Scheltema, Rudolf S.
Adams, Frank W.
Issue Date: Jan 1970
Publisher: University of Hawai'i Press
Citation: Robertson R, Scheltema RS, Adams FW. 1970. The feeding, larval dispersal, and metamorphosis of Philippia (Gastropoda: Architectonicidae). Pac Sci 24(1): 55-65.
Abstract: In the Hawaiian Islands , Philippia (Psilaxis) radiata (Reding)
lives in sand or rubble near the hermatypic stony coral Porites lobata Dana, and
emerges to feed at night on the polyps, Other species of Philippia (Psilaxis)
probably have the same mode of life with corals. Philippia (Psilaxis) veliger larvae
are abundant in tropical and subtropical oceanic plankton distant from any
potential shallow-water hosts, and are dispersed great distances by near-surface
currents. Duration of the pelagic larval stage is between several weeks and 6
months or longer. Metamorphosis, involving loss of the 4-lobed velum, initial
growth of the teleoconch, and other changes, can precede contact with a host and
is induced by capture from the plankton. Newly settled Philippia quickly attain
a stage of arrested growth and can remain alive without feeding for several
months . At this stage the postlarvae presumably crawl in search of hosts, and
failure to find hosts doubtless causes the high mortality observed.
Experiments at Woods Hole, Massachusetts, with newly metamorphosed P.
(Psilaxis) krebsii (March), obtained as larvae from plankton in the Sargasso Sea,
together with the ahermatypic coral Astrangia danae Agassiz, reveal physical problems
for Philippia in assuming the adult mode of life with other corals. Young
Philippia showed no ability to detect Astrangia except by touch. Young Philippia
lacked immuni ty to Astrangia nematocysts but were not seriously injured by them .
The young gastropods are, however, subject to predation by this coral. Most contacts
with the living tissues of Astrangia caused a Philippia to be promptly drawn
through the mouth and ultimately digested. The large protoconchs of Psilaxis
would preclude their being swallowed by hermatypic corals such as Porites, with
polyps smaller than those of Astrangia. Proboscis eversion and feeding were not
observed in young P. krebsii.
URI/DOI: http://hdl.handle.net/10125/4023
ISSN: 0030-8870
Appears in Collections:Pacific Science Volume 24, Number 1, 1970



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