Seahorses are helping scientists to study the evolution of pregnancy

Seahorses are wonderful fish. The male fish grows the developing embryos in his pouch with an organ similar to the placenta – studying the pregnancy of seahorses also enables scientists to better understand the adaptive processes of pregnancy in humans. An expert on seahorses from the Canary Islands is working together with the scientists from the University of Tartu.

By the way Francisco Otero-Ferrer introduces the life of seahorses, it is obvious he admires these mystical creatures. And it is not hard to see why – seahorses, such as the short-snouted seahorse (Hippocampus hippocampus) and the longsnout seahorse (Hippocampus reidi), are a group of fish whose characteristic appearance and swimming method cannot go unnoticed. Therefore, seahorses have already been piquing people’s interest for thousands of years, since the times of the ancient Greeks and Romans.

These enchanting animals belong to the Syngnathidae family, together with seadragons and pipefish – the common characteristic within this family is the fused jaw and eating method. With their elongated sucking apparatus, the seahorses pull all kinds of small invertebrates, but also fish and algae – whatever they can manage – into their mouths.

Seahorses are widely spread in various habitats: fields of seagrass, algae-covered and rocky underwater slopes, predominantly in tropical and subtropical seas, but also northwards up to Canada and the waters of the River Thames. Seahorses are terrible swimmers, but excellent at adapting to various living conditions (e.g., in the case there is no seagrass, they can also hold on to fishing nets) and are resilient aquarium fish. The latter is one of the many reasons why seahorses have become the model species for several research topics.

But it’s not all rosy. Due to their appearance, seahorses have found their way to Chinese medicine, they are kept in aquariums, and used as jewellery and souvenirs. Furthermore, seahorses are threatened by several problems related to environmental changes, such as the loss of suitable habitats. Many individuals are taken as by-catch by fishermen during daily fishing. The number of seahorses being sold for various purposes reaches 15 to 20 million per year.

Thus, the abundance of this attractive flagship species has begun to decrease dangerously. For example, in one of the best growing areas for seahorses – the Ria Formosa lagoon in Portugal – where approximately one million seahorses were counted in 2001, there were only 150,000 left in 2019. According to the International Union for Conservation of Nature (IUCN), 14 species out of the 42 are considered to be “threatened” and two “near threatened”.

The seahorse is a species with a unique reproductive biology

The reason why a scientist studying seahorses daily at the University of Las Palmas de Gran Canaria is participating in a joint research project with researchers from the Institute of Biomedicine and Translational Medicine at the University of Tartu is the unique way seahorses reproduce. And this is not that different from humans.