1972; Bristow et al. 2010a; Goto et al. 2012; Bhaduri et al. 2017). They are associated with a number of benthic and burrowing invertebrate phyla, e.g. Arthropoda,
Echinodermata, Annelida, Porifera, Brachiopoda, among others (Boss 1965a, b;
Wear 1966; Narchi 1969; Morton 1972; Mikkelsen and Bieler 1989; Kato 1998;
Sato et al. 2011; Goto et al. 2012, 2016; Li et al. 2012). Li et al. (2016) indicated,
that ancestral galeommatoideans were sediment-dwelling commensals with one
major free-living radiation into hard-bottom environments, coupled with losses of
commensalism. Commensals either live in or around host burrows, or attach by the
byssus threads directly to the host body surface (Morton and Scott 1989). Some do
attach inside the shell carried by their host—hermit crabs (e.g. Curvemysella paula;
Goto et al. 2007), inside the holothurian host esophagus (e.g. Entovalva spp.; Kato
1998), or inside the gill chamber of crabs (e.g. Kurtiella pedroana; Lafferty 1993;
Boyko and Mikkelsen 2002; Bhaduri et al. 2017). Presumably they benefit from
their habitat by both the anti-predator shelters and oxygen and food rich areas, e.g.
in result of the water currents pumped through the tunnel by their host (Morton and
Scott 1989; Boyko and Mikkelsen 2002; Goto et al. 2007). Goto et al. (2018) proposed, that evolution from sediment-dwelling to ectocommensal (or even endocommensal) lifestyle required a stage of a burrow-wall-commensal lifestyle.
Most species of the galeommatoid commensal bivalves are host specific
(Table 5.1). Sato et al. (2011) summarized that among 29 ectocommensal species
recorded from Japan, Korea and China, 23 were reported to attach directly on the
body or shell of only one host species. Goto et al. (2018) tested if the obligate ectocommensal Parabonia squilina collected from abdomen of mantis shrimp
Lysiosquilla scabricauda would reattach after removal—the bivalves crawled to the
host and attached by the byssal threads once their foot reached the host pleon.
Morton (1972) widely discussed the possible functional interpretation of the location of Pseudopythina subsinuata on its host stomatopod Oratosquilla oratorio—
the bivalve is always found attached (and returns if detached) by its byssus to the
lateral undersurface of the thorax of the host, possibly regarding the respiratory
currents and cleaning behavior of the stomatopod. Similar observations were illustrated by Dall (1899) (in Morton 1972) for Pseudopythina rugifera attached to the
undersurface of the mud shrimp Upogebia pugetensis (also Naeromya rugifera prefers this locality; Li and O’Foighil 2012). Scintillona brissae is always being found
attached to the anus area of the echinoderm Brissus latecarinatus (Morton and Scott
1989), while Waldo arthuri chooses oral surface of the echinoderm Brisaster latifrons (Valentich-Scott et al. 2013). Wear (1966) describes that Arthritica bifurca
attaches usually to the outer surface of polychaete Pectinaria australis tube—at the
head end of it. Sagamiscintilla thalassemicola crawles to the inside of the proboscis
gutter of the echiuran Anelassorhynchus sp., which is immediately closed and the
bivalve is completely enclosed by the host tissues. Similarly, all the four members
of the genus Entovalva live inside the esophagus of their holothurian hosts (Kato
1998; Bristow et al. 2010a). Such close relation may be granted by higher fitness of
offspring, if the commensal bivalve evolves specialized adaptations to a specific
host (cf. Reznick and Ghalambor 2001).
Echinodermata, Annelida, Porifera, Brachiopoda, among others (Boss 1965a, b;
Wear 1966; Narchi 1969; Morton 1972; Mikkelsen and Bieler 1989; Kato 1998;
Sato et al. 2011; Goto et al. 2012, 2016; Li et al. 2012). Li et al. (2016) indicated,
that ancestral galeommatoideans were sediment-dwelling commensals with one
major free-living radiation into hard-bottom environments, coupled with losses of
commensalism. Commensals either live in or around host burrows, or attach by the
byssus threads directly to the host body surface (Morton and Scott 1989). Some do
attach inside the shell carried by their host—hermit crabs (e.g. Curvemysella paula;
Goto et al. 2007), inside the holothurian host esophagus (e.g. Entovalva spp.; Kato
1998), or inside the gill chamber of crabs (e.g. Kurtiella pedroana; Lafferty 1993;
Boyko and Mikkelsen 2002; Bhaduri et al. 2017). Presumably they benefit from
their habitat by both the anti-predator shelters and oxygen and food rich areas, e.g.
in result of the water currents pumped through the tunnel by their host (Morton and
Scott 1989; Boyko and Mikkelsen 2002; Goto et al. 2007). Goto et al. (2018) proposed, that evolution from sediment-dwelling to ectocommensal (or even endocommensal) lifestyle required a stage of a burrow-wall-commensal lifestyle.
Most species of the galeommatoid commensal bivalves are host specific
(Table 5.1). Sato et al. (2011) summarized that among 29 ectocommensal species
recorded from Japan, Korea and China, 23 were reported to attach directly on the
body or shell of only one host species. Goto et al. (2018) tested if the obligate ectocommensal Parabonia squilina collected from abdomen of mantis shrimp
Lysiosquilla scabricauda would reattach after removal—the bivalves crawled to the
host and attached by the byssal threads once their foot reached the host pleon.
Morton (1972) widely discussed the possible functional interpretation of the location of Pseudopythina subsinuata on its host stomatopod Oratosquilla oratorio—
the bivalve is always found attached (and returns if detached) by its byssus to the
lateral undersurface of the thorax of the host, possibly regarding the respiratory
currents and cleaning behavior of the stomatopod. Similar observations were illustrated by Dall (1899) (in Morton 1972) for Pseudopythina rugifera attached to the
undersurface of the mud shrimp Upogebia pugetensis (also Naeromya rugifera prefers this locality; Li and O’Foighil 2012). Scintillona brissae is always being found
attached to the anus area of the echinoderm Brissus latecarinatus (Morton and Scott
1989), while Waldo arthuri chooses oral surface of the echinoderm Brisaster latifrons (Valentich-Scott et al. 2013). Wear (1966) describes that Arthritica bifurca
attaches usually to the outer surface of polychaete Pectinaria australis tube—at the
head end of it. Sagamiscintilla thalassemicola crawles to the inside of the proboscis
gutter of the echiuran Anelassorhynchus sp., which is immediately closed and the
bivalve is completely enclosed by the host tissues. Similarly, all the four members
of the genus Entovalva live inside the esophagus of their holothurian hosts (Kato
1998; Bristow et al. 2010a). Such close relation may be granted by higher fitness of
offspring, if the commensal bivalve evolves specialized adaptations to a specific
host (cf. Reznick and Ghalambor 2001).