Monogamy, spawning and skin-shedding of the sea moth, Eurypegasus draconis (Pisces: Pegasidae)

Abstract

SynopsisThe Red Sea seamoth, Eurypegasus draconis, has a social structure that involves close pair-bonding with a monogamous mating system. The occurrence of 61 specimens, 95.1% paired, were recorded in the Gulf of Aqaba, during summers 1989 and 1990. Fourteen pairs were tagged and seven of them were seen again at least once. Cumulative location maps for tagged individuals showed that they were not territorial or site-attached, home ranges of pairs overlapped, they had low mobility, and occurred in low densities. Dissections and histological analyses showed that pairs (n= 12) were heterosexual and all individuals were sexually mature. E. draconis is sexually dimorphic. Females (n= 13) have significantly larger carapace volumes than males (n= 13). In aquaria, pairs spawned repetitively at dusk. At the peak of a spawning rise they released pelagic eggs from which embryos hatched in 24-29 h at 27.2" C. Unpaired individuals probably have little opportunity to meet and mate. Close pair-bonding that ensures the availability of a mate, probably evolved as a style for increasing reproductive success in these small fish that occur in low density. E. draconis sheds its skin in one piece every 1 to 5 days.

Serial monogamy in the European long-snouted seahorse Hippocampus guttulatus

“…Social monogamy is employed as a mating strategy across many taxa, including fish (Herold and Clark 1993;Matsumoto and Yanagisawa 2001;Egger et al 2006). Social monogamy is not, however, necessarily an accurate indicator of a genetically monogamous mating system (Wilson and Martin-Smith 2007).…”

Trade in pegasid fishes (sea moths), primarily for traditional Chinese medicine

“…Sexes of E. draconis do not differ in total length or colour but the female has a larger carapace volume while the male has a significantly longer tail and rostrum (Herold and Clark, 1993). P. lancifer's colours are usually beige/brown/green but both sexes are highly cryptic, capable of rapid colour change to match the substrate (Kuiter, 1985).…”

“…The few brief studies of pegasid biology indicate that the same pairs of one male and one female mate repeatedly -perhaps because of their low density and low mobility -but show neither parental care nor site fidelity (Pegasus lancifer; Kuiter, 1985; Eurypegasus draconis; Herold and Clark, 1993). Pegasids walk or crawl along the bottom on their pelvic fins, only occasionally using their large pectorals to 'fly'.…”

“…In both species, males' snouts are more slender and proportionally longer than those of females. Pegasids shed their skin in one complete piece every 1-5 days, presumably to rid themselves of accumulated epibiotic growths of algae, hydroids and other organisms (Kuiter, 1985;Herold and Clark, 1993). Strict carnivores,…”

“…Drawn by Lana J. Koepke and reproduced with the permission of Wayne A. Palsson. they feed by sucking small epifaunal and interstitial invertebrates from the sediment/ water interface (Herold and Clark, 1993). They have been known to fall prey to larger pelagic fish such as tuna (Palsson and Pietsch, 1989) and to birds such as penguins (Kuiter, 1985).…”