Advancing marine conservation
The trade in seahorses for aquarium fishes is contributing to the depletion of many wild populations of these animals. Many seahorses are sold to replace those that have died in captivity as a result of husbandry problems. It can be particularly difficult to rear the young seahorses, because of their need for varied live food …
Seahorses (Hippocampus spp) are heavily exploited in Vietnam, but conservation and management measures are currently limited by the ambiguous taxonomic definitions of the genus in the region. Seven species of seahorse are identified in this paper as inhabiting the coastal waters of Vietnam. We used morphometric and DNA sequence data (from the cytochrome b region …
Pegasid fishes (sea moths) have only entered the arsenal of traditional Chinese medicine within the past few decades, but are now used in southern China and Hong Kong to treat respiratory ailments and cancers. Brief trade surveys suggest that millions of individuals of two pegasid species are used each year, and that they cost relatively …
Synopsis Pipefishes have rarely been watched in the wild and have never before been followed in their common seagrass habitats. This study explores the reproductive ecology of five species of pipefishes living in a Swedish eelgrass meadow during parts of four breeding seasons, tagging four of the species. Pipefish are remarkable for their specialised paternal …
Genetic evidence has revealed that sexual fidelity is rather rare in supposedly monogamous animals. Pairing, whether sexually faithful or not, is very uncommon in fish and has not previously been confirmed in fish from seagrass habitats. Here, the first underwater study of seahorse reproduction reveals that males and females of an Australian species (Hippocampus whitei) …
In an aquarium, a female seahorse was presented with a choice of mates: her previous mate to whom she had just transferred her eggs and who was placed in a separate aquarium or new mates in the same aquarium with whom she socially interacted and greeted on a daily basis. In 6 experiments, the female …
Over the past 20 years, long-term studies have shown that mammalian fathers, brothers and even unrelated males may contribute substantially to the care of the young. Recently, more field studies of mammals with male care have further expanded interest in male care potential. Male mammals can never be sole care-givers because offspring depend on maternal …
In the pipefish Syngnathus typhle, only males brood embryos in specially developed brood pouches, supplying oxygen and nutrients. Laboratory studies have shown that this elaborate paternal care has led to sex-role reversal in this species: males limit female reproductive rate, females are the primary competitors for mates and males exercise greater selectivity in accepting mates. In …
Contrary to all expectations based on their male pregnancy, recent work shows that seahorses exhibit conventional sex roles in mating competition: male seahorses compete more to obtain eggs than females do to give their eggs away. This suggests that the operational sex ratio (OSR: the relative number of males and females available to mate) might …
In seahorses, only males undergo a pregnancy. It had been tacitly and explicitly assumed that seahorses were sex role reversed (that females competed more intensely than males for access to mates), on the basis that male pregnancy so limited male reproduction as to produce a female-biased operational sex ratio (OSR). However, this supposition had never …