(CNN)Scientists from the Cascadia Research Collective have discovered a rare dolphin-whale hybrid off the coast of Kauai, Hawaii, according to a report published last week.
The marine mammal monitoring program, funded by the US Navy, first spotted the animal in August 2017. The team tagged various species, including commonly seen rough-toothed dolphins and rarer melon-headed whales.
However, researchers soon noticed that one tagged animal that looked a little odd. Although it had a typical melon-headed whale's dorsal fin shape and dorsal cape, it was also blotchy in pigmentation and had a sloping forehead, more reminiscent of a rough-toothed dolphin.
A genetic sample soon confirmed their suspicions: it was a hybrid of the two species, the first to ever be found.
The cross-species hybridization may seem bizarre, but is made possible by the fact that melon-headed whales aren't actually whales. They belong to the Delphinidae family, otherwise known as oceanic dolphins, which also includes orcas and two species of pilot whales.
It also isn't the first discovery of hybridization in the family -- there have also been cases of bottlenose dolphin/false killer whale (Pseudorca crassidens) hybrids, known as Wolphins, and common/bottlenose dolphin hybrids.
This is the first confirmed hybrid between rough-toothed dolphins and melon-headed whales. However, though it's an exciting discovery, researchers point out it is not, as commonly thought, a new species.
"While hybridization can at times lead to new species, most of the time this does not happen," Cascadia researcher Robin Baird told CNN, pointing that there was only a single hybrid found this time.
Some hybrid animals, such as the mule -- a hybrid of a male donkey and female horse -- are mostly sterile and therefore cannot propagate easily.
The dolphin-whale hybridization is especially surprising in this region, as a sighting of melon-headed whales had never before been confirmed near the Pacific Missile Range Facility (PMRF) navy base.
The hybrid was only traveling with one companion -- a melon-headed whale. This, too was unusual, given that melon-headed whales typically travel in groups of 200-300. The solitary pair were "found associating with rough-toothed dolphins," the report read.
The odd pair and their closeness to the other dolphins have led the researchers to speculate that the accompanying melon-headed whale is the hybrid's mother.
The research team will return to Kauai next week, hoping to confirm their theory.
"If we were lucky enough to find the pair again, we would try to get a biopsy sample of the accompanying melon-headed whale, to see whether it might be the mother of the hybrid, as well as get underwater images of the hybrid to better assess morphological differences from the parent species," said Baird.
The US Navy is required to monitor these species as part of the Marine Mammal Protection Act and the Endangered Species Act.
They do so through the Cascadia Research Collective, which conducts photo identification, genetic analyzes, and acoustic monitoring to determine the abundance of odontocetes, also known as toothed whales.