For the first time ever, scientists have identified the genetic underpinnings that give seahorses their unique horse-like body features using genome sequencing.
In a study featured in the journal Nature, researchers in Singapore, China, and Germany have successfully sequenced and examined the genome of a seahorse. They were able to discover several molecular factors that contribute to the animal's rapid evolution.
Explaining The Seahorse's Equine Features
Seahorses are known for having physical features that are very rare for fish species. Instead of having scales like other bony fish, these creatures have bony plates covering their entire body. They also lack the signature tail or pelvic fin of other fish.
The heads of seahorses have features similar to those of terrestrial horses with long, tube-like snouts but without teeth. They can also use their eyes independently, allowing them to look forward and backward at the same time.
Males of the species are known to have a brood pouch, which allows them to carry embryos and give birth to their offspring instead of the females.
This unique body structure makes seahorses such an interesting animal to study for evolutionary scientists.
"They are such iconic animals, one of the examples of the exuberance of evolution," Axel Meyer, an evolutionary biologist from the University of Konstanz in Germany and one of the authors of the study, said.
To understand how these creatures get their horse-like features, Meyer and his colleagues sequenced the genome of a Southeast Asian tiger tail seahorse and analyzed each underpinning. They discovered that seahorse lack an important gene known as tbx4.
Almost all known vertebrates have the tbx4 gene in their genome. The fact that it's missing in seahorses could help explain why the animals don't have pelvic fins much like other fish species.
The researchers tested this theory by deactivating the gene in zebrafish using the CRISPER-cas method. This resulted in the zebrafish losing their pelvic fins as well.
Meyer and his team also found that seahorses are capable of duplicating their genes. Once a certain gene is duplicated, the resulting copy can take on an entirely different body function.
The researchers believe this process is what allows male seahorses to become pregnant. After an embryo hatches inside the male's brood pouch, it will activate additional genes that could influence the offspring's ability to leave their father's body.
The genes responsible for teeth development in humans and other animals were found to be mutated in seahorses. To compensate for their lack of teeth, seahorses had to come up with a way to use their snout to suck in plankton and other tiny organisms for food.
