Tongue-eating louse discovered in the mouth of a fish by a student in South Africa

What’s the matter, louse got your tongue? Parasite which bites off a fish’s tongue and then REPLACES it is discovered by a shocked student in South Africa

  • Tongue-eating louse is a parasite which preys on fish, entering through their gills
  • Louse bites tongue’s blood vessels and drinks from them until tongue falls off  
  • Parasite then latches on to the tongue stump, effectively replacing the organ 
  • Shocked student in South Africa discovered a louse in the mouth of his catch

It is an idea so horrifying that it sounds made up: A parasite which bites off its host’s tongue and then replaces it, living inside its mouth for the rest of its life.

But in fact, the tongue-eating louse is real and lives inside the mouths of fish – one of which was discovered recently by a shocked student in South Africa.

Don Marx, 27, from Cape Town, was fishing near Cape Agulhas when he hooked the six-pound carpenter fish and discovered the stowaway inside its jaws.  

Marx, who happens to study marine biology, had heard of the lice but never seen one in the wild – so snapped a picture to document the moment.

A tongue-eating louse in the fish's mouth

Don Marx, 27, from Cape Town, was surprised to find a tongue-eating louse living in the mouth of a carpenter fish he caught off the coast of South Africa

But after he sent the photo to Professor Nico Smit, a zoologist at North-West University, he was delighted to discover this particular species of louse has never been photographed before 

‘Being a marine scientist and having fished since a young age, I’ve see my fair share of parasites living on fish and sharks,’ he said.

‘But nothing could really prepare me for the moment I opened the carpenter’s mouth and saw this blue eyed alien with a moustache staring back at me.

‘This specific species of tongue eating louse only uses carpenters as their host and has eluded scientists for years.

The louse enters its host through the gills, bites off its tongue and replaces the organ, living in the fish's mouth for the rest of its life

The louse enters its host through the gills, bites off its tongue and replaces the organ, living in the fish’s mouth for the rest of its life 

‘When we allow ourselves to slow down and look around us, nature reveals all of her magic to us.’ 

Tongue-eating lice have been known about for decades, but only in recent years have serious studies begun into their life cycles and behaviour.

It is thought that all species of tongue-eating lice begin their lives as males, drifting in the ocean and looking for fish to latch on to.

Each species of louse – with over 280 identified so far – appears to target just one species of fish.

Once the louse has found a host fish of the right species, it swims through the fish’s gills and makes itself at home.

If the host fish does not have any other lice already in place, the new louse makes its way into the mouth, where it attaches itself to the tongue.

The louse will sever the blood vessels in the tongue and then drink the blood.

During this time, the male will transform into a female – its body increasing several times in size while its eyes dwindle since it no longer needs to navigate around.

When the tongue eventually dies and falls out due to lack of blood, the louse latches on to the tongue stump and effectively replaces it.

Mr Marx caught the fish off Cape Agulhas (pictured) and was delighted to find that this particular species of louse had never been photographed before

Mr Marx caught the fish off Cape Agulhas (pictured) and was delighted to find that this particular species of louse had never been photographed before

It is the only known species of parasite that completely replaces the function of an organ in its host.

The parasite will then live in the fish’s mouth for the rest of both their lives, feeding on the fish’s blood and mucus, but otherwise causing no other harm.

If the louse finds that a female is already in place when it enters the fish, it will remain as a smaller male and attach to the fish’s gills instead.

It will remain there, and occasionally breed with the female inside the fish, producing live young which are expelled through the gills after birth to find their own host.

Fish which have several males attached to their gills are known to be under-weight, likely due to the parasites feeding on their blood.

It is not known what happens to the tongue lice when their host dies in the wild, though it is likely that they perish as well.