368
In contrast to Elopomorpha, osteoglossiform fi shes display a considerable
variability in inner ear morphology and hearing abilities. Mormyridae and
Notopteridae possess ancillary auditory structures. Mormyrids have intracranial gas
bladders—parts of the swim bladder that become isolated from the main swim bladder during ontogenetic development—that contact the saccule (Stipetić 1939 ; Braun
and Grande 2008 ). In Notopteridae, anterior projections of the swim bladder abut
the skull in the region of the saccule (Coombs and Popper 1982 ). Both groups have
highly modifi ed ears, i.e. the vertical pattern of the macula sacculi in mormyrids
(Fig. 4a ) and a complex trilobate macula sacculi with a modifi ed alternating pattern
in the Clown knifefi sh Chitala chitala (Notopteridae; Fig. 5a ). Nonetheless, the
hearing improvement is more distinct in mormyrids than in C. chitala . Mormyrids
are sound pressure sensitive and detect sounds up to several kilohertz ( Brienomyrus
brachyistius : 100–4000 Hz, Yan and Curtsinger 2000 ; Gnathonemus petersii : 100–
2500 Hz, McCormick and Popper 1984 ), whereas C. chitala detects sounds only up
to 1000 Hz (Coombs and Popper 1982 ).
Osteoglossiforms without ancillary auditory structures have either a standard
( Osteoglossum bicirrhosum , Osteoglossidae) or an alternating pattern ( Pantodon
buchholzi , Pantodontidae) on the macula sacculi (Coombs and Popper 1980 ; Popper
1981 ); they have limited hearing abilities, detecting frequencies up to 500 Hz ( O.
bicirrhosum ) (Coombs and Popper 1980 )
2.3.2 Otomorpha (Clupeiformes; Anotophysa + Otophysa)
All clupeiform fi shes are characterized by swim bladder extensions that form two
intracranial parts enveloped by bone, namely the pterotic and prootic bullae. The
membrane of the gas-fi lled part of the prootic bulla is connected to the middle part
of the macula utriculi (=macula media) via a thread-like suspension (Wohlfahrt
1936 ; O’Connell 1955 ; Blaxter et al. 1981 ; Higgs et al. 2004 ; Wilson et al. 2009 ).
The unique tripartite macula utriculi (Fig. 4c ) (Popper and Platt 1979 ; Platt and
Popper 1981b ; Higgs et al. 2004 ) is in part (middle and posterior macula) overlain
by a highly modifi ed utricular otolith (Wohlfahrt 1936 ; O’Connell 1955 ). This otolith has a tetrahedral shape and thin extensions in anterolateral and ventral directions instead of the “stone-like” appearance present in most teleosts (Wohlfahrt
Fig. 4 (continued) Within otophysans the maculae and their orientation patterns show low variability; ariid catfi shes, however, are characterized by a unique elongate instead of bowl-shaped
macula utriculi, forming an equatorial band curving around the large utricular otolith. Note that the
macula utriculi is fi gured below the macula sacculi and macula lagenae. No ventral part of the
macula utriculi is found in this group. All clupeiform fi shes possess a highly modifi ed tripartite
macula utriculi, whereas macula sacculi and macula lagenae are similar to those in teleosts without
ancillary auditory structures. From left to right : macula sacculi, macula lagenae, macula utriculi.
Note that in ( a ) only the macula sacculi and macula lagenae are shown. All illustrations are
redrawn from Ladich and Popper ( 2001 ), Platt ( 1977 ), Platt and Popper ( 1981b ), Popper ( 1981 ),
Popper and Platt ( 1979 ), and Popper and Tavolga ( 1981 ). The schematic fi sh illustrations are modifi ed from Ladich, this volume. a anterior, d dorsal, lat lateral
T. Schulz-Mirbach and F. Ladich
In contrast to Elopomorpha, osteoglossiform fi shes display a considerable
variability in inner ear morphology and hearing abilities. Mormyridae and
Notopteridae possess ancillary auditory structures. Mormyrids have intracranial gas
bladders—parts of the swim bladder that become isolated from the main swim bladder during ontogenetic development—that contact the saccule (Stipetić 1939 ; Braun
and Grande 2008 ). In Notopteridae, anterior projections of the swim bladder abut
the skull in the region of the saccule (Coombs and Popper 1982 ). Both groups have
highly modifi ed ears, i.e. the vertical pattern of the macula sacculi in mormyrids
(Fig. 4a ) and a complex trilobate macula sacculi with a modifi ed alternating pattern
in the Clown knifefi sh Chitala chitala (Notopteridae; Fig. 5a ). Nonetheless, the
hearing improvement is more distinct in mormyrids than in C. chitala . Mormyrids
are sound pressure sensitive and detect sounds up to several kilohertz ( Brienomyrus
brachyistius : 100–4000 Hz, Yan and Curtsinger 2000 ; Gnathonemus petersii : 100–
2500 Hz, McCormick and Popper 1984 ), whereas C. chitala detects sounds only up
to 1000 Hz (Coombs and Popper 1982 ).
Osteoglossiforms without ancillary auditory structures have either a standard
( Osteoglossum bicirrhosum , Osteoglossidae) or an alternating pattern ( Pantodon
buchholzi , Pantodontidae) on the macula sacculi (Coombs and Popper 1980 ; Popper
1981 ); they have limited hearing abilities, detecting frequencies up to 500 Hz ( O.
bicirrhosum ) (Coombs and Popper 1980 )
2.3.2 Otomorpha (Clupeiformes; Anotophysa + Otophysa)
All clupeiform fi shes are characterized by swim bladder extensions that form two
intracranial parts enveloped by bone, namely the pterotic and prootic bullae. The
membrane of the gas-fi lled part of the prootic bulla is connected to the middle part
of the macula utriculi (=macula media) via a thread-like suspension (Wohlfahrt
1936 ; O’Connell 1955 ; Blaxter et al. 1981 ; Higgs et al. 2004 ; Wilson et al. 2009 ).
The unique tripartite macula utriculi (Fig. 4c ) (Popper and Platt 1979 ; Platt and
Popper 1981b ; Higgs et al. 2004 ) is in part (middle and posterior macula) overlain
by a highly modifi ed utricular otolith (Wohlfahrt 1936 ; O’Connell 1955 ). This otolith has a tetrahedral shape and thin extensions in anterolateral and ventral directions instead of the “stone-like” appearance present in most teleosts (Wohlfahrt
Fig. 4 (continued) Within otophysans the maculae and their orientation patterns show low variability; ariid catfi shes, however, are characterized by a unique elongate instead of bowl-shaped
macula utriculi, forming an equatorial band curving around the large utricular otolith. Note that the
macula utriculi is fi gured below the macula sacculi and macula lagenae. No ventral part of the
macula utriculi is found in this group. All clupeiform fi shes possess a highly modifi ed tripartite
macula utriculi, whereas macula sacculi and macula lagenae are similar to those in teleosts without
ancillary auditory structures. From left to right : macula sacculi, macula lagenae, macula utriculi.
Note that in ( a ) only the macula sacculi and macula lagenae are shown. All illustrations are
redrawn from Ladich and Popper ( 2001 ), Platt ( 1977 ), Platt and Popper ( 1981b ), Popper ( 1981 ),
Popper and Platt ( 1979 ), and Popper and Tavolga ( 1981 ). The schematic fi sh illustrations are modifi ed from Ladich, this volume. a anterior, d dorsal, lat lateral
T. Schulz-Mirbach and F. Ladich