Ear Structure of Deep-Sea Fishes
Deng, X., Wagner, H.-J.,
and Popper, A. N. (2011).
The Inner Ear and its Coupling to the Swim Bladder in the Deep-Sea
Moridae). Deep Sea Research, part I, 158:27-37.
fishes dwell between 1000 and 5000 meters. At these depths there
is little or no light, food is scarce, and there are considerable
distances between individuals. Thus, we hypothesize that these fishes
have evolved acoustic communication and auditory specializations.
Since such fish rarely can be taken alive, the only way to study
their hearing is to extrapolate from anatomical studies.
We are interesting in
a broad range of deep-sea fish species, currently we have several
active projects on three families of benthopelagic deep-sea fishes:
I. Comparative studies
of the morphology and ultrastructure of the inner ears in nine species
of deep-sea Macrouridae fishes.
|Fig. 1 - Dorsal
view of brain and ears of C. armatus
|Fig. 2 - Saccular
macula of C. rupestris
The Macrourid fishes,
often called rat-tails and grenadiers, are the most abundant species
in the bethopelagic fauna. This group of fishes is very successful
in deep-sea environments in that they can be found in all deep-sea
areas on the earth and occupy a wide range of depths. The nine species
included in this study are Coryphaenoides rupestris, C. mediterraneus,
C. leptolepis, C. armatus, C. brevibarbis, C. guentheri, C. profundicolas,
Nezumia aequalis, and Coelorhyncus occa. These species range in
depth from 1000 meters to 4000 meters.
Figure 1 shows a whole
view of the brain and ears of C. armatus. These macrourid
species have relatively large saccules and ellipsoid shaped otoliths.
The orientation of the hair cell ciliary bundles in the saccule
is similar to that found in the Atlantic cod (Gadus morhua)
(Dale, 1976), and in the deep sea Gadiform Bregmaceros (Popper,
1980), with a bi-directional vertical pattern in the middle, and
a gradual shift to a bi-directional horizontal pattern at both ends
The lagenae of the Coryphaenoides
have lagenar otoliths that are often shaped like a saddle with different
patterns of fluting along the edges (Fig. 3). Up to one-half to
three-quarters of each macula surface is not covered by the otolith,
but rather by the otolith membrane which extends beyond the otolith
3 - Lagena of C. rupestris
||Fig. 4 - Lagena macula and otolith
of C. rupestris
II. Anatomical study
of a gadiform deep-sea fish Antimora rostrata
The blue antimora (Antimora
rostrata) is a bathypelagic morid cod obtained at 2,500 m depth.
Its inner ear has a number of unique morphological and ultrastructural
features. The walls of the three otolithic end organs are rigid
and partially sclerotic, with tight attachments to all of the surrounding
bones. The saccule in this species has a very large and heavy otolith
(Fig.5). The saccular macula (epithelium), which is exceptionally
thin and long, is in three distinct segments, and can also be divided
into eight regions according to the hair cell bundle orientation
||Fig. 5 - Left and
right ears of Antimora rostrata
||Fig. 6 - Left saccular
macula of Antimora rostrata