Meet Micronesia’s ‘Manta Mum’

These amazing animals have the biggest brain of any fish species.

One of life’s certainties is that we will face many unknowns. Similarly, in our natural world there exist many facets that are yet to be explored and understood.

Julie Hartup is a woman whose life took an unexpected turn, leading her down the path to discover the secrets of one of the Western Pacific Ocean’s most enigmatic fish: the manta ray. In this edition of the BBC Earth podcast, you can hear Julie’s first-hand accounts of meeting this graceful and improbable creature.

Hartup’s journey into studying manta rays was by no means a conventional one.

She grew up in a conservative Mormon community in Provo, Utah – a 10-hour drive from the nearest coastline – in the USA. By the age of 19, she was married and went on to have three children.

Her decision to become a scuba diving instructor meant that by the age of 28 her marriage was over, after her husband made her choose between him and diving.

In an attempt to better provide for her family, she decided to train as a marine biologist which ended in her moving to the tiny island of Guam in the Pacific’s Micronesia to study the enigmatic manta rays.

Manta ray
Despite their large size, it can sometimes be difficult to find manta rays, as they travel vast distances to feed. © Giordano Cipriani | Getty
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“They’re not always the easiest animals to study because they’re not always around. I did 25 surveys in a row and found nothing.”

A breakthrough occurred after a conversation with a friend which led Hartup to hypothesise that mantas were feeding off fish spawn in the ocean.

“The whole key really is finding out where the food is.’

“I know fish like to spawn around certain Moon phases, so I looked at the Moon phase and my hypothesis was to go out on this date and find these fish that are spawning.”

For certain fish species, reproduction is a carefully engineered activity.

On the reef studied by Hartup in Micronesia, thousands of surgeon fish gather when the time is just right and the tide is at its highest. They simultaneously release millions of eggs and sperm which fertilise each other and drift off into the ocean current.

Sure enough, when Hartup tested out her hypothesis she saw 14 manta rays show up, feeding off the fish spawn.

Nobody really knows how the manta rays are so in tune with the tides that they are able to turn up at the exact right moment, but the scene was captured in the latest David Attenborough landmark series, A Perfect Planet.

By now, Hartup has been studying manta rays for over a decade, so she was able to help the Perfect Planet team locate them.

And for the woman who is dubbed the ‘Manta Mum’ on her tiny island of Guam, these creatures never cease to fascinate.

“Some of them are a little bit shyer; other ones want to come out and check you over,’ she says.

“I never tire of seeing mantas; luckily I have to do it a lot.”

Sometimes nicknamed ‘devil fish’, owing to the horn-shaped fins that adorn their heads, manta rays have the largest brains of all fish species.

Manta ray and scuba diver
Upon studying manta rays, Julie Hartup found them to be incredibly curious. © Steven Trainoff Ph.D. | Getty

For Julie Hartup they’re ‘curious’ creatures, each with their own distinct personalities. On the island of Guam in Micronesia where she lives, Hartup even has a favourite manta who she refers to as ‘Sweet Samantha.’

“She’s so curious, so whenever she comes over, she immediately comes straight to you,” says Hartup.

“And then she kind of does this banking, she turns on her side and banks around you.”

It’s like they see you. They see your soul."

Julie HartupMarine Biologist

Studies by scientists have suggested that manta rays may be able to recognize themselves in a mirror.

The 2016 study found that manta rays exposed to a mirror displayed ‘unusual self-directed behaviours’ which showed possible evidence of self-awareness, found in other animals such as apes.

“It’s their eye that really gets me,” says Hartup.

“It’s like they see you. They see your soul. That’s how I feel: that they see exactly who I am."

Featured image © Ken Kiefer 2 | Getty


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BBC Earth Podcast

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Intimate stories and surprising truths about nature, science and the human experience in a podcast the size of the planet.