Alternative Male Mating Behaviors Dependent on Relative Body Size in Captive Oval Squid Sepioteuthis lessoniana (Cephalopoda, Loliginidae)

Abstract

We observed the reproductive behavior of the oval squid Sepioteuthis lessoniana in captivity. The male used three different mating behaviors: male-parallel (MP), male-upturned (MU) and sneaking. Male competition over females frequently occurred before and during the female egg-laying period, and the outcome of most fights depended on male body size. Larger males guarded their partners from other males and performed MP mating during the egg-laying period of the paired females. In contrast, there was no pairing and mate guarding in MU mating and sneaking, which were adopted by smaller subordinate males as alternative tactics outside female egg-laying period and during the period, respectively. MP matings were 95% successful, but more than half of MU matings were unsuccessful. Higher mating success in MP mating was achieved through pairing, whereas males in MU mating were less successful because mating attempts without pair formation were often foiled by escape of the female. Sneaking was successful in all cases but occurred less frequently. Spermatophores were attached at the opening of the oviduct in MP mating, whereas they were attached around the female buccal membrane in MU mating and sneaking. Considering the route of egg transportation, higher fertilization success can be expected in MP mating because of the advantageous location of the attached spermatophores. Our results suggest that MP mating is used by larger, paired males during the female egg-laying period, and that MU mating and sneaking are alternative tactics adopted by smaller, subordinate males. These alternative mating behaviors would be conditional strategy dependent on relative body size, because some individual males displayed both MP and MU mating behaviors.

Quantitative Analysis of Dynamic Body Patterning Reveals the Grammar of Visual Signals during the Reproductive Behavior of the Oval Squid Sepioteuthis lessoniana

“…other males and perform male-parallel mating during the egglaying period of the paired females, whereas smaller subordinate males used male-upturn mating as an alternative tactic outside the female egg-laying period (Wada et al, 2005). These results suggest that males of different sizes may adopt different strategies in order to gain access to females, and females may choose different males in order to maximize their reproduction success.…”

“…Squids are polyandrous, in which a female mates with multiple males during a spawning season (Jantzen and Havenhand, 2003b;Iwata et al, 2005;Wada et al, 2005). For S. lessoniana, alternative male mating behaviors have been found to depend on the relative body size of the squid.…”

“…In addition, it has been observed that male squids showed agonistic behavior and fight for the possession of the female during reproductive interactions (Moynihan and Rodaniche, 1982;Jantzen and Havenhand, 2003b). Cephalopods are highly visual animals and they communicate through dynamic body patterning, thus it is likely that visual communication between males and females during courtship behaviors, as well as between different males during agonistic behavior, may determine their mating strategies (Hanlon et al, , 2002(Hanlon et al, , 2005Jantzen and Havenhand, 2003a,b;Naud et al, 2004Naud et al, , 2016Iwata et al, 2005;Wada et al, 2005;Huffard et al, 2008;Buresch et al, 2009;Scheel et al, 2016).…”

“…However, the oval squid Sepioteuthis lessoniana which is widely distributed in IndoWest Pacific waters (Jereb and Roper, 2005) has not been systematically examined and neither have their dynamic body patterns during reproductive behavior been determined. Similar to other cephalopods, it has been shown that S. lessoniana also undertake diverse mating behaviors and show a wide variety of body patterns (Wada et al, 2005). In the present study, we aimed to (1) examine whether different reproductive behaviors are associated with specific body patterns, (2) determine whether some chromatic components are co-expressed for particular behaviors, and (3) assess whether certain components are specific to a particular behavior or are used in multiple contexts.…”

“…Many studies have suggested that most cephalopods utilize polyandry, which is where a female mates with multiple males during the spawning season (Hanlon and Messenger, 1996;Hanlon et al, 2005). Previous studies have shown that females not only mate with large size males in a group (the consorts) but also mate with other smaller males (the sneakers) using distinct types of courtship behavior (Hanlon et al, , 2002(Hanlon et al, , 2005Jantzen and Havenhand, 2003b;Naud et al, 2004Naud et al, , 2016Iwata et al, 2005;Wada et al, 2005;Iwata and Sakurai, 2007;Huffard et al, 2008;Sato et al, 2014). These results suggest that males of different sizes may adopt different strategies in order to gain access to females and that females may during the same process choose different males in order to maximize their reproduction success.…”