Studies of the Phoront of Hyalophysa chattoni (Ciliophora, Apostomatida) Encysted on Grass Shrimp¹

Abstract

ABSTRACT. The apostomatous ciliate Hyalophysa chattoni, an ectosymbiont of the grass shrimp Palaemonetes pugio, encysts and dedifferentiates within 48 h from the migratory tomite to a phoretic stage devoid of complex ciliary fields. The presettlement crawling and pivoting of the tomite may play a role in its initial attachment to the shrimp. Metamorphosis of exuviotrophic apostomes has been previously observed to take place immediately prior to host ecdysis. The study has found that Hyalophysa's metamorphosis to the feeding stage on grass shrimp is initiated by a cue from the premolt host and begins during earlier stages of the molt cycle (D0 and D1). Due to the long premolt stage of the host's diecdysic molt cycle, metamorphosis is initiated well before ecdysis (over six days). Hyalophysa was able to encyst and metamorphose within 41/4 h when exposed to shrimp in a late premolt stage, indicating that the control of apostome metamorphosis is solely host‐dependent.

Variations in the Ventral Ciliature of the Crustacean Symbiont Hyalophysa (Ciliophora, Apostomatida) from Mobile Bay and Dauphin Island, Alabama

“…Of all of the changes that take place during this transformation, the formation of the AVF The dissolution of FF9 i s a process that occurs normally during the phoretic stage ofHyalophysa to form the AVF (Bradbury and Trager 1967). Landers (1986) described this metamorphosis using protargol silver impregnation (see Figures I 1-1 3) and suggested that Ka is a derivative from the posterior fragment of FF9. This hypothesis is confirmed by the present data.…”

Exuviotrophic Apostome Ciliates from Crustaceans of St. Andrew Bay, Florida, and a Description of Gymnodinioides kozloffi n. sp.

“…An anterior ventral field of kinetosomes (AVF) is present, developed from FF9 in the phoront (Fig. 3, 4) (Bradbury and Trager 1967a; Landers 1986). AVF kinetosomes mostly in groups of 2–3.…”

“…Eventually, selection of protozoans that can survive on non‐ideal hosts may lead to new protozoan species that are genetically isolated and adapted to the new host. Earlier work has examined the role of host pre‐molt cues on apostome metamorphosis and ex‐cystation (Bradbury and Trager 1967b, Landers 1986). The work of Bradbury and Trager (1967b) demonstrated that apostome phoronts can respond to glycogen, suggesting that bloodstream glycogen levels may be an important signaling cue to the protozoan.…”

“…The work of Bradbury and Trager (1967b) demonstrated that apostome phoronts can respond to glycogen, suggesting that bloodstream glycogen levels may be an important signaling cue to the protozoan. Landers (1986) demonstrated that the metamorphosis from the phoront to the trophont in H. chattoni is tied to the molt cycle stage of the host Palaemonetes pugio , and that tomites settling on a pre‐molt animal speed up their metamorphosis in order to be ready for the host's ecdysis. Many substances in the host's urine or bloodstream could be signals for the ciliates.…”

Genetic analysis of ciliates living on the groundwater amphipod Crangonyx islandicus (Amphipoda: Crangonyctidae)

“…In a study on estuarine shrimp by Landers (1986), phoronts were mainly found under the branchiostegite and on the antennal plates of the host while Ohtsuka et al (2004) documented phoronts of the species Vampyrophrya pelagica mainly on swimming legs and ventral side of the prosoma of the copepod hosts. In a study on estuarine shrimp by Landers (1986), phoronts were mainly found under the branchiostegite and on the antennal plates of the host while Ohtsuka et al (2004) documented phoronts of the species Vampyrophrya pelagica mainly on swimming legs and ventral side of the prosoma of the copepod hosts.…”