These images show how desperately rare short-tail nurse sharks have been born in captivity at an aquarium in Spain for the first time.

Short-tail nurse sharks are listed as critically endangered on the International Union for Conservation of Nature’s (IUCN) Red List of Threatened Species and are only found in the tropical western Indian Ocean in the wild.

It is the first time that youngsters have been hatched at the Oceanografic de Valencia Aquarium, in south-eastern Spain.

Astonishing video footage of the process shows the baby sharks developing in their eggs from the size of a fingernail.

Six months later – when they are eventually born – the pups are shown being hand fed by keepers.

The aquarium said in a statement on Monday, 18th July: “The birth of the offspring represents a success for the conservation of the species, which has decreased by nearly 80 percent in the last 30 years.”

Short-tail nurse sharks (Pseudoginglymostoma brevicaudatum) are “nocturnal sharks that are distributed throughout the Indian Ocean”.

The aquarium added: “Since last June, the Oceanografic de Valencia has had two new short-tailed nurse shark pups.”

They said that until recently, the species had been listed as ‘vulnerable’ but they are now deemed ‘critically endangered’ after no data about the species was recorded in their natural habitat for more than 15 years.

The tiny sharks only reach a size of 75 centimetres (29.5 inches) when fully grown and are “characterised by being a nocturnal species that lives in dark and rocky areas, such as caves and spaces with very little light, where they take refuge and lay their eggs, since they are an oviparous animal with seasonal spawning.”

The aquarium said that the eggs were spawned in December.

After being found by keepers, they were moved to a special quarantine zone at the aquarium so that they could be closely monitored, with the embryos checked on a daily basis.

The aquarium said that both of them are males and that they are fed three times a day with a special porridge that is made up of herring, squid and hake.

When they are large enough, they will be returned to the main aquarium building, where four adult members of their species currently reside.

The aquarium explained that the loss of their habitat is primarily due to global warming.

They can mainly be found in the Indian Ocean, “specifically in the areas of Tanzania, Mozambique and Madagascar”.