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Beaks of Sepia officinalis individuals reared for this study at A. 0 days old (hatching day), B. 15 days old and C. 20 days old (scale bar = 50 μm)
Source publication
This is the first study addressing validation of the early growth stages (including the first increment) in the beaks of juvenile cuttlefishes. The age validation in juveniles of Sepia officinalis was performed by comparison of the number of increments observed in the rostrum surface of lower jaws with their true age. A total of 159 individuals wer...
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Citations
... Additionally, the internal shell (cuttlebone) of S. officinalis was utilized to examine age; however, no relationship was found between the number of counted lamellae and the actual age of the animals [25]. More recently, in this species, the beak has been taken into account for aging investigations considering adult sizes [28,29] and early stages [30] using the rostrum surface, but the daily deposition of increments has been validated only in the latter study. Currently, there is no study related to the age estimation of the common cuttlefish in the Mediterranean. ...
... The overall readings' precision and accuracy were evaluated by the coefficient of variation (%CV) [33], and the mean number of increments of the readings was considered [14,30]. The relationships between NI, ML, and TW were described separately for both sexes with four different curve models: linear, exponential, power, and logarithmic. ...
Simple Summary
Determining the age of cephalopods is essential for understanding their life history, which is in turn crucial for assessment and management. The short lifespan with a single reproductive event, high natural mortality rates, and rapid growth in these species make the application of traditional age-based models impractical. Most hard structures of cephalopods, such as mandible (beaks) and statoliths, can store ontogenetic events through the formation of periodic marks or growth increments. Statoliths are paired calcareous structures located in two anterior chambers of the head. In this work, for the first time in the Mediterranean, we successfully performed age estimation in wild cuttlefish Sepia officinalis using beaks and statoliths. Based on daily increments that were previously validated in statoliths, the beaks were cross-verified. As the beak presented more advantages in age studies than statoliths, due to the relative simplicity of its processing method, it was eventually proposed as a suitable hard structure to study the age of S. officinalis.
Abstract
Establishing the age of cephalopods is crucial for understanding their life history, which can then be used for assessment and management. This is particularly true for the common cuttlefish Sepia officinalis (Linnaeus, 1758), one of the most important resources for coastal fisheries. For this reason, an age analysis of S. officinalis was performed for the first time in the Mediterranean, using beaks and statoliths from 158 wild specimens (55–222 mm mantle length; 23–1382 g total weight) at different maturity stages (immature to mature). Growth increments were counted in the lateral wall of the upper beaks and the lateral dome of statoliths. In both cases, a good relationship was found between the counts and the sizes of the animals. The low values of coefficients of variation between the readings obtained for beaks (3.96 ± 1.87%) and statoliths (4.00 ± 1.89%) showed a high level of precision and accuracy in the readings. However, the analysis was simpler for beaks, which were all successfully analyzed, while it was more complex for statoliths, with 69% being lost due to rejection or overgrinding. Based on daily increments previously validated in statoliths, the beaks were cross-verified by comparing their counts with those from statoliths extracted from the same 83 specimens, obtaining a statistically significant relationship between the two counts, confirmed by the ANOVA test. Absolute growth rates that were assessed using both beaks and statoliths indicated that the two sexes had a higher growth rate at 122 and 182 days, which subsequently declined in older specimens. Due to the relative simplicity of its processing method, the beak was finally proposed as a suitable hard structure to study the age of S. officinalis. We also confirmed the good readability of increments in the lateral wall of the beak, which could be considered a valid alternative to the rostrum surface.
... Direct methods using hard structures, such as statoliths, beaks, lenses, or gladius, based on the study of growth increments have proven to be the most useful method for estimating the absolute age and the growth of cephalopods. Growth increment analysis in jaws has been shown to be an appropriate technique for age determination, validated in other benthic cephalopods, such as O. vulgaris (e.g., Hernández-López et al. 2001;Canali et al. 2011;Perales-Raya et al. 2014b;Armelloni et al. 2020), O. maya (e.g., Rodríguez-Domínguez et al. 2013;Bárcenas et al. 2014), or Sepia officinalis (Guerra-Marrero et al. 2023). The recent revision of Xavier et al. (2022) provides detailed information on the attempted study of other cephalopod species using beak increment analysis, as well as those with confirmed daily deposition and validated ontogenetic stages. ...
In this study, we explored the feasibility of using the beaks of the African cuttlefish Sepia bertheloti for age estimation and growth analysis. The rostrum sagittal section (RSS) of the lower beak was the most suitable region in the species. It was applied in samples caught off Morocco and Guinea-Bissau between June 2018 and January 2020. A maximum life expectancy of around 14 months was observed (specifically 419 days for cuttlefishes from Morocco and 433 from Guinea-Bissau). The males presented greater longevity, as the maximum age of the females was between 9 and 11 months. Sepia bertheloti showed a negative allometric growth; however, the exponential model better describes each population growth. By sexes, the males of both locations followed an asymptotic growth model while the females exhibited a non-asymptotic growth. The growth rates were different between locations, with the highest values in Guinea-Bissau. The males, in turn, grew faster for both study locations. In Guinea-Bissau, these growth differences were influenced by the hatching season since individuals born between autumn and winter were the fastest-growing. Samples from Morocco did not show growth differences between the hatching season and other seasons. These results indicate that the RSS of lower beaks are suitable for estimating the age, growth pattern, and population structure of Sepia bertheloti .
... These cells are arranged in a thin cell layer located between the aboral side of the beak and the surrounding muscles (Dilly and Nixon 1976). The increments are generally deposited daily (Perales-Raya et al. 2010;Arkhipkin et al. 2018;Guerra-Marrero et al. 2023), and the deposition rate has been validated by experimental data using stress markers visible on the increments (Perales-Raya et al. 2014a, b, 2018. As daily growth was observed in most species investigated, this growth pattern may be widespread among cephalopods, with potential rate variation depending on environmental conditions Schwarz et al. 2019). ...
Due to their small size, juveniles are more likely to show lower absolute levels of performance leading to a potential competitive disadvantage compared to adults. Therefore, juveniles are expected to compensate by showing a higher relative performance, and/or partitioning resources to overcome this performance disadvantage. Here, we investigate the link between ontogeny and feeding performance in the common cuttlefish Sepia officinalis. We explore the changes in beak shape, wear pattern, mechanical properties, muscular anatomy, and bite force during growth from 3-month post hatching to adults. We show that both upper and lower beaks present important ontogenetic shape variation in the rostrum area that might be due to wear induced by feeding. The mechanical properties of the beaks in juveniles indicate greater resistance compared to adults. Tanning observed on the beaks provides reinforcement to areas under high load during biting. In addition, muscle development and relative bite force were found to differ between cuttlefish of different ages, resulting in juveniles having a similar bite force for their size but with a muscular advantage for opening. Finally, an isometric relation is found in the bite force of S. officinalis, with no sign of feeding performance compensation in juveniles. Feeding performance thus does not reflect the ontogenetic shift from a crustacean-based diet in juveniles to a fish-based diet in adults.
Rapana venosa (Valenciennes, 1846) is an invasive species that has spread widely around the world, which has
commercial importance. For scientifically sound fishery management, accurate age determination is necessary,
while the methods currently used have disadvantages. To fulfill the need for a more accurate technique, the
microstructure of R. venosa statoliths collected in the northern part of the Black Sea (near the Bolshoy Utrish
cape) was studied. Statoliths have well-marked concentric increments, which allows counting with sufficient
accuracy. The annual periodicity of R. venosa statolith increments was cross validated using spawning marks on
the shells. The growth of veined whelks was the best described by Von Bertalanffy function, with the following
coefficients: L∞ = 96.19; k = 0.125; t0 = 0.043. The model accounted for 83% of variance. Moreover, the
possibility to reconstruct the age of molluscs based on statolith diameter was tested. It was revealed that the
number of increments versus statolith diameter relationship is exponential, the developed model described 99%
of variance. Based on these data the growth of R. venosa was modelled again, resulting model accounted for 88%
of variance. Coefficients of the model were: L∞ = 106.42; k = 0.102; t0 = 0.136. Potential benefits and limitations
of the applied methods are discussed.
