The most identifiable part of a seahorse is the long snout that gives them their name. But did you know there is a species of seahorse that evolved their snout away?
The pygmy seahorse, one of the smallest vertebrates measuring around the size of your thumbnail, does not have the iconic horse-like snout of other seahorses. A new study in the Proceedings of the National Academy of Science looked into why this species of seahorse lost their long snout and came up with the answer by sequencing the pygmy seahorse’s genome for the first time.
The reason for the pygmy seahorse’s stubby nose? To help them blend into the coral they call home.
“Seahorses usually have an elongated snout that resembles a horse[…]. However, this would set the pygmy seahorse apart from the coral’s shape,” said Axel Meyer, professor at the University of Konstanz, in a press release. “We were highly interested in finding out at what stage of development this deviating appearance of the pygmy seahorse is caused to provide good camouflage and which genes are responsible.”
What Does the Pygmy Seahorse Look Like?
The pygmy seahorse is just the size of a thumbnail and is difficult to spot thanks to its camouflage.
(Image Credit: Frank Schneidewind)
Pygmy seahorses are known as being masters of disguise, blending perfectly into the specific type of coral they cling to. Over time, they have evolved to adapt their body shape and color so that they remain undetected while latched onto the coral, patiently waiting for food to float by. Their camouflage skills are so effective that they were only discovered by scientists 45 years ago and remain a very elusive species of underwater creature.
At a young age, pygmy seahorses look just like other species of seahorses. At early stages of development, seahorses all have short and squat snouts that give them a cute, baby-like appearance. However, while other seahorse species grow out of this child-like look, pygmy seahorses remain stuck there forever.
“Normally, a combination of different genetic components causes the snout of a seahorse to grow proportionally faster than other parts of the body from a certain age and thus become elongated. In the pygmy seahorse, however, we have now discovered that these different growth rates are suppressed because the hoxab2b gene has been lost,” said Meyer in the press release.
Read More: The Pygmy Right Whale Was the Family Weirdo, and it Never Went Extinct
Sequencing the Pygmy Seahorse Genome
To learn more about these genetic losses, scientists analyzed the pygmy seahorse’s genetic expression during different developmental stages. Through this analysis, a few surprising differences appeared between pygmy seahorses and other seahorse species.
Along with discovering that the pygmy seahorse’s small snout is due to a genetic loss, the research team found that pygmy seahorses also lost an unexpectedly large number of immune genes. Additionally, they discovered that pygmy seahorses have the smallest known set of immune-related genes not only of all seahorse species but of all vertebrates.
“This is probably due to the fact that coral toxins can be tolerated by the pygmy seahorses and even provide them with protection against microbes. Consequently, their immune system no longer needs the corresponding genes,” said Meyer in the press release.
Overall, these discoveries about the pygmy seahorse’s unique genetics make them the perfect example of evolution at work. They took what was advantageous for them and, over millions of years and many generations, left everything else behind.
Read More: Fish Teeth Show That Ease of Evolution Is Its Own Evolutionary Advantage
Article Sources
Our writers at Discovermagazine.com use peer-reviewed studies and high-quality sources for our articles, and our editors review for scientific accuracy and editorial standards. Review the sources used below for this article:
- Proceedings of the National Academy of Science. Symbiosis with and mimicry of corals were facilitated by immune gene loss and body remodeling in the pygmy seahorse
