How old are giant squids? First approach to aging Architeuthis beaks

Abstract

The giant squid Architeuthis dux Steenstrup, 1857 is one of the largest and most enigmatic marine species. Its age estimation remains controversial with many estimates of maximum age ranging from 1 to 14 yrs. Successful results regarding the study of aging in cephalopod beaks for some octopod and oegopsid squids support using these structures for age estimation. We analyzed the beaks of 10 individuals, caught between 1995 and 2006, with reconstructed dorsal mantle lengths (DMLs) between 823 and 1418 mm. The beaks were measured and weighed, and their microstructure was analyzed in three ways: (1) in the rostrum area [rostrum sagittal sections (RSS)] for both upper and lower jaws, and the (2) inner lateral wall surfaces (LWS) and (3) inner crest surfaces (CS) for upper jaws. A constant sequence of increments was observed along the RSS, indicating that the use of lower jaws is more feasible due to the higher erosion and tighter packing of increments of upper jaws. The statolith of one individual was analyzed, resulting in 520 increments (579 increments from RSS of its lower jaw). Assuming daily deposition, the age estimations in RSS between 411 and 674 d suggest rapid growth of A. dux, averaging 1.97 mm DML d–1 (SD 0.45). When maximum ages were estimated by applying these results to the largest measured specimens in the literature (e.g., 2400 mm DML), an age of approximately 3 yrs was obtained. Analysis over a greater size range of individuals would allow more accurate age estimations of this emblematic squid.

The significance of cephalopod beaks as a research tool: An update

“…In relation to using beaks for age determination in cephalopods, it was found that the tip erosion during the feeding process may bias increment counts in the anterior region of the beak but counting the oldest increments in the dorsal area of the section prevents age underestimation (Arkhipkin et al, 2018). A simple method has been recently developed to quantify the tip erosion using the number of increments in the dorsal non-eroded region and the width of increment of the central reading region (Perales-Raya et al, 2020). Moreover, the beak microstructure of emblematic deepsea species such as the giant squid Architeuthis dux (Perales-Raya et al, 2020) (Figure 5) provided age data and a maximum lifespan estimation of around 3 years, based on rostrum sagittal sections from the lower beaks.…”

“…Artificial intelligence could provide a useful tool to save time and improve the detection and count of increments since it could "learn" from the images previously analysed by experienced readers. Finally, the cumulative width of the daily increments could be a potential tool to estimate growth in the wild, before capture (e.g., Perales-Raya et al (2020) for Architeuthis dux; Queirós, Bartolomé, Xavier and Perales-Raya, unpublished for M. longimana). Preliminary results on reared O. vulgaris used correlations between cumulative widths and body mass to estimate the growth in the wild, before capture (Perales-Raya, Bartolomé, Márquez, Felipe and Almansa, unpublished data).…”

“…Cephalopod beaks can also provide considerable information on a wide range of physiological, biological and ecological traits, including cephalopod availability, consumption of cephalopods, migrations, competition between cephalopod predators, levels of cephalopod scavenging by predators, distribution, age, growth, cohorts, life-events, stress, thermal changes, reproduction, feeding ecology, behavior, spawning areas, post-spawning mortality and sexual dimorphism [e.g., see review in Xavier et al (2016) and Arkhipkin et al (2018); Table 1]. More recently, new emergent techniques for work on beaks (e.g., stable isotope and trace elements analyses, geometric morphometrics and microstructure analysis) have provided further information on habitat and trophic position, composition, contamination, response of cephalopods to climate variability at individual and/or population levels, embryonic morphogenesis, paralarval ontogeny, ecology and age estimation (Cherel and Hobson, 2005;Perales-Raya et al, 2014b;Xavier et al, 2016;Perales-Raya et al, 2018;Queirós et al, 2018;Golikov et al, 2019a;Golikov et al, 2019b;Northern et al, 2019;Abreu et al, 2020;Queirós et al, 2020a;Armelloni et al, 2020;Queirós et al, 2020b;Franco-Santos and Vidal, 2020;Golikov et al, 2020;Perales-Raya et al, 2020;Fang et al, 2021b;Lishchenko and Jones, 2021). Consequently, the importance of cephalopod beaks in ecological studies continues to attract attention and recognition, with various workshops being organised (Clarke, 1986;Xavier et al, 2007a;Jackson et al, 2007;Xavier et al, 2015).…”

Age and growth estimation of Southern Ocean squid Moroteuthopsis longimana: can we use beaks collected from predators’ stomachs?

“…More recently, this technique has also been applied in other cephalopod species, e.g. the octopods Megaleledone setebos (Schwarz et al 2019), Octopus maya (Bárcenas et al 2014), the sepiid Sepia officinalis (Lishchenko et al 2018) and the oegopsid squid Dosidicus gigas (Liu et al 2015(Liu et al , 2017Hu et al 2016), Ommastrephes bartramii (Liu et al 2015;Fang et al 2016), O. caroli (Agus et al 2021), Sthenoteuthis oualaniensis (Liu et al 2015;Lu et al 2022) and Architeuthis dux (Perales-Raya et al 2020). Age determination in beaks have been mainly performed in two beak regions: the rostrum sagittal section (RSS) and the inner lateral wall surface (LWS) (Perales-Raya et al 2010).…”

Macroevolutionary Trade-Offs and Trends in Life History Traits of Cephalopods Through a Comparative Phylogenetic Approach

“…Body length can range from less than 1 cm in pygmy squids (Idiosepius spp.) with short life spans, to more than 20 m in total length (including tentacles) in the giant squid (Architeuthis dux), with a lifespan of around 3 years (Wood and O'Dor, 2000;Jereb and Roper, 2005;Perales-Raya et al, 2020). Similarly, variability in egg size can range from approximately 0.5 to 80 mm, while fecundity estimates vary from one or a few dozen eggs (e.g., cirrates, Nautilus, Sepiola, and Bathypolypus) to several millions (e.g., Architeuthis and Dosidicus), depending on body size (Calow, 1987;Boyle and Rodhouse, 2005;Laptikhovsky et al, 2018).…”