Washington: Pufferfishes are known for their peculiar and extreme skin structure, but how they came to possess the spikes on the body known as spines remained a mystery. Recently researchers identified the genes responsible for the evolution and development of pufferfish spines.
“Pufferfishes are some of the strangest fish in the ocean, particularly because they have a reduced skeleton, beak-like dentition and they form spines instead of scales not everywhere, but just in certain patches around the body,” said the corresponding author Gareth Fraser in the study published in the journal of ‘iScience.’
Fraser and his team followed the development of pufferfish spines in embryos. While they had initially hypothesised that the spines formed from scales that the pufferfish lost its scale component but retained the spine they found that the spines are developmentally unique from scales.
“It just blows me away that regardless of how evolutionarily different skin structures in animals are, they still use the same collection of genes during development,” said Fraser.
The researchers then decided to look at what would happen if they manipulated those genes. Using CRISPR-Cas9 and other genetic techniques, the researchers blocked particular genes that are classic markers of skin appendage development. Doing so allowed them to reduce the number of spines on Pufferfish, as well as loosen the restriction on where the spines appear on the Pufferfish.
Normally, the spines are localised to specific areas on the Pufferfish. Fraser said that this localisation of the spines is to enhance protection.
“When a pufferfish inflates by ingesting water or in some cases air, their skin becomes stretched, especially around the abdomen and is more susceptible to damage, such as being torn. Spines reinforce the puffed-up abdomen. In extreme cases, some Pufferfish have lost all other spines on their body and retain only the abdominal spines,” he said.
The reason for the diversity in spine coverage is likely ecological, Fraser said.
“What really drives these changes, in terms of loss or gain of spines, is multifactorial, but the shifts in spine coverage and morphology may allow pufferfish to take advantage of new ecological niches that are available to them. As the climate changes and environments become different, pufferfish may use these evolving traits to tolerate and adapt to change,” he concluded.