Cymothoa exigua is a parasite that is also know by the name the ‘Tongue-eating louse’. It is an isopod with the unique identifiable feature of being the only known parasite that functionally replaces a host’s organ. The louse enters the fish’s body through the gills, attaches to fish’s tongue and extracts blood, causing it to shrivel and eventually fall off. Once this has been achieved the louse attaches to the remaining stub and acts as a replacement tongue, receiving nutrients by feeding on the fish’s blood and mucus. While the majority of fish found with these parasite’s are underweight, there is no evidence that this parasite causes a significant amount of harm to its host.
These parasites, while aesthetically disturbing, are also not harmful to humans. While a person has brought a lawsuit against a supermarket chain after finding cymothoa exigua in fish they had eaten, the legal case was dropped. This was a result of there being no evidence that these parasites were in any way unhealthy for humans, they are not poisonous and can be incorporated into a healthy diet.
Giant otters are a great indicator species- one that shows the health of the ecosystem. Why? Because each adult otter needs to eat about 4kg/8lbs of fish every day. These otters live in family groups of up to 20 individuals so collectively require a huge amount of fish to support them. As a result, the presence of giant otters on a lake or river indicates a very productive area. I filmed this family fishing in the Northern Pantanal, Brazil, on assignment for @stevewinterphoto, @natgeo and @natgeowild
This month, I ventured to ask the man behind the counter at a Whole Foods Market what kind of shrimp he was selling. “I don’t know,” he replied. “I think they’re just normal shrimp.” I glanced at the sustainable seafood guide on my phone. There were 80 entries for shrimp, none of them listed “normal.”
What about the cod? Was it Atlantic or Pacific? Atlantic. How was it caught? I asked. “I’m not sure,” he said, looking doubtfully at a creamy fish slab. “With nets, I think. Not with harpoons.”
The shrimp had a blue sticker shaped like a fish on it, which appeared to be some type of official approval. Plus, they were on sale. I bought half a pound.