I once heard that if you spend too much time studying or living with an animal, you end up resembling that animal and that animal ends up resembling you.

This is the story of Benjamín and Daniel. One of the many stories that happen under the rocking cadence of the waves in our Caribbean Sea, a story that can be told and understood only as time passes, because only then can change be recognized in its entirety.

This story takes place in Chetumal, which in the Mayan language means, “the place where the rains come down.” This is the trustworthy account of a Mexican scientist who, since 1990, has been transforming into a manatee, slowly but surely, before everyone’s eyes.

It is also the story of a baby manatee born as an orphan in 2003 and who for two decades has stubbornly tried to become one of us — flick by flick of his tail and smile by smile on his face.

But let’s start from the beginning.

Manatees originated 6.5 million years ago (way before humans walked on the planet) from an ancestral lineage that lived in Colombia’s Magdalena River. From South American rivers, these mermaids migrated to the ocean, taking advantage of marine currents to navigate the Atlantic and some eventually reach Africa.

Today, three species of manatees survive, but all are threatened with extinction. They swim in the fresh and marine waters of America and Africa.

One of the three living species is the American manatee, inhabiting the coasts of Florida, Mexico, Central America, the Caribbean islands and south to Brazil. Another one is the manatee of the Amazon and Orinoco rivers in South America. The third is the African manatee.

They are all herbivores, mild-mannered migratory mammals that roam in warm waters. Sailors have confused them with mermaids for millennia — although some less poetic people call them sea cows. Truth be told, they are more closely related to elephants.

And, as we had done with those serene pachyderms, for many years, we relentlessly hunted manatees to devour their skin, fat, meat, teeth and their souls.

I met Dr. Benjamín Morales many years ago, when he studied sea lions and I studied great whales in the Gulf of California. He did so under the tutelage of a Chilean marine mammalogist who left Chile in 1973 after the coup d’état that killed President Salvador Allende. He eventually made Mexico his home until returning to Chile 10 years ago.

I was under the guidance of an American ichthyologist who in 1977 moved from California to Baja California, promising to never go back if Governor Ronald Reagan ever became the U.S. president; in 1981, Reagan was elected president, and that ichthyologist settled here.

Those two men, now octogenarians, were pioneers of modern scientific research on Mexico’s marine mammals, and they nurtured scores of students. They now live 10,000 kilometers apart: one in Guaymas in the Gulf of California, the other in Punta Arenas in the Magallanes Region of Chilean Antarctica.

When I saw Daniel for the first time, I was moved by his manatee smile: a smile that exposes his massive molars — a warm-hearted, easygoing love-filled merman. His is a smile that invites you to pat, cuddle and smile back.

Daniel, as most manatees, loves to be pampered. With his two bulky prehensile upper lip lobes, he incessantly throws kisses to the left and to the right, while displaying his massive teeth and the most captivating smile in the entire animal kingdom.

He has a big heart, a small brain, eyes the size of human ones, huge nostrils and a pair of tiny auditory holes that give him extraordinary acoustic capability. Since Daniel doesn’t have vocal cords, he is almost mute; he can produce only a few sounds through pharyngeal vibrations.

Mute Daniel reminds me of Quasimodo, that unforgettable character in Victor Hugo’s 1831 novel, The Hunchback of Notre Dame: massive, brave, astute, with a heart of gold and longing for the impossible.

With each day that passes, Benjamín and Daniel look more like each other. The two met on September 14, 2003, in Laguna Guerrero, near Chetumal. Daniel was stranded on the beach alone — newly born and already an orphan. He still had the umbilical cord that had connected him to his mum for 12 months; she died of unknown causes.

Not thinking twice, Benjamín the man, adopted Daniel the manatee.

I have asked myself if Dr. Morales thought precisely about what he was going to do with a baby manatee; I doubt it. The calf’s irresistible smile certainly captivated him, suddenly and forever.

As it happened, Daniel was taken to a pond in El Colegio de la Frontera Sur in Chetumal, a scientific institution where Dr. Morales worked. The baby manatee was nursed for many days and nights with a baby’s bottle by his new dad and the young enthusiasts of Chetumal who also surrendered their hearts to the most enchanting smile in the animal kingdom.

For 13 years, Daniel lived in semi-captivity in a place that national and international NGOs and foundations built especially for him, when he was the star of the moment. He was the only guest and had frequent visitors.

Then, in May 2016, Daniel was freed, and I can only imagine Benjamín’s broken heart when he opened Daniel’s pond doors to allow him to go to see the world in the company of his kin.

But despite Dr. Morales’ efforts to make him independent, Daniel the manatee did not want to leave. Sometimes he leaves for a few days, weeks or even months, but he always comes back. And every time he returns, I imagine the bittersweet mix of happiness and sorrow that overwhelms Benjamin. It is like when a father encourages his adult son to leave home but deep inside his heart yearns for him never to leave.

Daniel spends his life eating, resting, thinking, exploring and letting himself be cherished. Like Benjamín does. The two never stop smiling, even at the most critical moments, such as when — abandoned and forgotten by all — starving Daniel languished because the big donor NGOs, foundations and authorities no longer wanted to pay for his food.

Everyone turned their backs on Daniel — but not the manatee man who with his only salary bought lettuce, jicamas and carrots every day to appease the ravenous appetite of his beloved adopted son.

Because, you should know, dear reader, manatees eat between 10% and 15% of their body weight each day, and they feed on almost any kind of aquatic vegetation. This is why Daniel and his kin are natural agents controlling the excessive growth of vegetation along navigation and irrigation channels. And, in doing that, they protect our health and economies.

If only for that, we must respect and take care of them.

In September next year, Daniel will turn 20. He could reach a maximum age of 65 years — exactly the age that his friend Benjamín is today. Benjamín retires at the end of this year after dedicating his life to discovering all the secrets of the manatees of Chetumal Bay. He will now devote his life to sustainable agriculture and to writing his memoirs.

I close my eyes and imagine Benjamín slowly walking toward the ocean in the twilight of his life while anxiously looking for the uplifting smile of his amigo Daniel near one of the docks of the bay.

I cannot stop thinking of the other manatees Dr. Morales has baptized and tagged with satellite radios to spy on their lives: Pancho, Luna, Yolanda, Leonardo, Angie, Yubarta and Poseidon. Today, 150 manatees roam Chetumal Bay and along the Yucatán Peninsula.

This, then, is the incredible story of a manatee who dreamt to be a man and of a man who turned into a manatee.

It fills me with hope knowing that in the entire Caribbean there are thousands of women and men turning, every day, into jaguars, pink dolphins, vaquita porpoises, sharks, crocodiles, frogs, owls, condors, golden eagles, armadillos and, above all, orchids.

We are a legion with a mission: saving the magnificent biological diversity of our beloved Latin America for this and future generations.

Omar Vidal, a scientist, was a university professor in Mexico, is a former senior officer at the UN Environment Program and the former director-general of the World Wildlife Fund-Mexico.