Carl Hayden Community High School teacher Fredi Lajvardi and his science students investigated the birth and discovered that it's rare, the Arizona Republic reported Tuesday.

"As far as we know, we are the third case worldwide," Lajvardi told the Phoenix newspaper.

This type of birth is known as parthenogenesis, in which an unfertilized egg develops into a new pup, said Lajvardi, program manager for the Carl Hayden Center for Marine Science.

"Normally, it would recombine with the father's half of the gene," the teacher said. "But because there is no father, the mother provided the other half."

The week-old pup, which students named Dawn, was born to the white-spotted bamboo shark living in one of the school's marine-science classrooms, the Republic reported.