Fish otoliths: do sizes correlate with taxonomic group, habitat and/or luminescence?

Abstract

Otoliths are dense structures in the ears of fishes that function in hearing and gravity perception. Otolith (sagitta) diameters, as percentages of standard length (% SL), are calculated for 247 marine fish species in 147 families and compared by taxonomic group (usually order), habitat and presence or absence of luminescence. Otolith sizes range from 0.4-31.4 mm and 0.08-11.2% SL. The eel and spiny eel orders Anguilliformes and Notacanthiformes have small to very small otoliths, as do the triggerfish order Tetraodontiformes, pipefish order Gasterosteiformes, billfish suborder Scombroidei and many of the dragonfish order Stomiiformes. The soldierfish order Beryciformes has moderate to very large otoliths. The perch order Perciformes has a wide range of otolith sizes but most have small to moderate otoliths 2-5% SL. Only 16 out of the 247 species have the relatively largest otoliths, over 7% SL. Seven out of these 16 species are also luminous from a variety of habitats. Luminous species have slightly to much larger otoliths than non-luminous species in the same family Both beryciforms and luminous fishes live in low-light environments, where acute colour vision is probably impossible. Most fishes of the epipelagic surface waters have very small otoliths, perhaps due to background noise and/or excessive movement of heavy otoliths in rough seas. Bathypelagic species usually have small otoliths and regressed or absent swimbladders. Other habitats have species with a range of otolith sizes. While the relationship between hearing ability and otolith length is unknown, at least some groups with modified swim-bladders have larger otoliths, which may be associated with more acute hearing.

Stock discrimination of two insular populations of Diplodus annularis (Actinopterygii: Perciformes: Sparidae) along the coast of Tunisia by analysis of otolith shape

“…In addition to the environmental parameters (Aguirre and Lombarte 1999, Torres et al 2000, Volpedo and Echeverría 2000, Gauldie and Crampton 2002, Volpedo and Fuchs 2010, also other factors have effect on the otoliths, they include ontogenetic factors (Tombari et al 2005, Gonzalez Naya et al 2012, physiological factors as the hearing capabilities associated with specialization in acoustic communication (Popper and Fay 1993, Paxton 2000, Lombarte and Cruz 2007, and the phylogeny (Nolf and Tyler 2006). All of those could affect the morphology, the morphometry, and the microstructure of sagittae ).…”

“…This variability is especially true for the saccular otolith (sagitta) associated with the inner ear organ, sacculus, in non-ostariophsean fi shes (Platt andPopper 1981, Lombarte andCruz 2007). The morphological differences affect both the size and shape of the otoliths (Paxton 2000).…”

Using sagittal otoliths and eye diameter for ecological characterization of deep-sea fish: <i>Aphanopus carbo</i> and <i>A. intermedius</i> from NE Atlantic waters

“…occurs in deeper waters in the Canary Islands and Madeira may be in order to avoid overlapping with the trophic niches of other trichiurids as well as other species, such as Promethichthys prometheus (Pajuelo et al, 2008). Previous studies have concluded that otolith size is related to the habitat and behaviour of species (Paxton, 2000;Tuset et al, 2003;Volpedo and Echevarría, 2003). In most cases, it has been demonstrated that an increase in the depth distribution of species that live below 1000 m also implies an increase in otolith size (Lombarte and Cruz, 2007;Schulz-Mirbach et al, 2008).…”

The life history of weedy seadragons, Phyllopteryx taeniolatus (Teleostei:Syngnathidae)

“…Otoliths, which are the most common hard structures used to age teleosts, were not located or removed from the weedy seadragons examined, even after microscopic examination of the cranium. Paxton (2000) suggested that elongate epipelagic species have very small otoliths as a result of excessive background noise in turbulent waters that would interfere with an acute sense of hearing. These organisms generally have large eyes to compensate for the lack of acute hearing (Paxton 2000).…”

“…Paxton (2000) suggested that elongate epipelagic species have very small otoliths as a result of excessive background noise in turbulent waters that would interfere with an acute sense of hearing. These organisms generally have large eyes to compensate for the lack of acute hearing (Paxton 2000). Weedy seadragons have large welldeveloped eyes; therefore, a keen sense of hearing may not be as important for these ambush predators as precise vision, and as a result, otoliths may be absent or microscopic in weedy seadragons.…”