HAVANA  |  Tue Apr 21, 2015 12:17pm BST

Ten baby crocodiles arrived in Cuba on Monday from a Swedish zoo where they had been born to a pair of Cuban crocodiles that former President Fidel Castro had given to a Soviet cosmonaut as a gift in the 1970s.

The Cuban crocodile species is endangered by loss of habitat, hunting and interbreeding with the American crocodile.

"There are very few of them left, maybe 100, and now they have 10 more," said Jonas Wahlstrom, a well-known zookeeper in Sweden who accompanied the animals on a flight to Havana. "They are the most beautiful and rarest crocodile species, and also the most aggressive."

Wahlstrom spoke upon landing and had not yet seen the animals, all 20-month-old siblings and about 1 meter (1.09 yards) long, because they had been held in the cargo compartment.

"For some reason KLM (the airline) did not want crocodiles in the passenger section," Wahlstrom said.

Castro gave the parents, born in 1974, to cosmonaut Vladimir Shatalov as a token of friendship, but Shatalov had nowhere to keep them and placed them in a Moscow zoo.

"His wife didn't want to share an apartment with two growing crocodiles," Wahlstrom said. Cuban crocodiles generally grow to 2.5 to 2.8 meters long, about 8 to 9 feet.

The Moscow zoo didn't have the right facilities either and transferred the crocodiles to Stockholm's Skansen zoo in 1981. Wahlstrom, who has looked after them since 1984, named them Hillary and Castro in the 1990s.

Cuban crocodiles generally live into their 80s and mate their entire lives, Wahlstrom said. The offspring should have no trouble adapting to the wild, he said.

The 10 hatchlings, still too young to determine their sexes, will be kept in quarantine in Havana. Wahlstrom said he hoped they would be released during his week-long stay in Cuba, so he could watch them return to the swamp.

"That's my dream."