Parasites have colonized the oceans of the globe and survive at the expense of a host that has no choice but to accept them. Be careful, everything coming next is nightmarish.
This strange fish is considered as one of the oldest vertebrates on Earth. With inward curved teeth, lampreys cling to the skin of a fish then pierce a hole and suck the blood flowing from the wound. We find some species of lampreys who are even more voracious, going deep inside the gills of their hosts.
The candiru is a well known fish in the Amazon River. Indeed, some people in this geographical area have made a day the unfortunate experience to urinate in the water. This fish whose senses are particularly developed, followed the flow of heat and installed directly into the urethra. Apart from this accidental interference, the candiru often step into fish gills to feed on the blood and flesh of its victim.
Maybe the most famous of all parasites, over 100 marine species are currently registered. They can be found in the seven seas of the world hung on fishes, turtles or amphibians. Leeches have some amazing features: they breathe through the pores of the skin, have two hearts and they are highly resistant to pollution.
Silver pearl fish
The Silver pearl fish built its home in an unusual place: the anus and part of the digestive tract of a sea cucumber This fish stays and circulates freely in this place sheltered from predators. Unfortunately for the sea cucumber, some of these fish-pearls are deleterious parasites that eat the internal organs of those which hosted them.
This sea lice doesn’t look like the one which attacks the hair of your children. This aquatic crustacean parasites only pink snappers. Making its way into the mouth of the host through the gill, the parasite will divert blood flow irrigating the tongue to its own advantage. Subsequently, the language will atrophy and the parasite will functionally replace the missing organ. The fish will be able to use the parasite just like a normal tongue. This example is exceptional because it is the unique case of parasitism leading to complete and functional organ replacement.
It is not good to be a crab in the ocean. In addition to many predators, the crab was chosen as a target by a crustacean parasite. This parasite sneaks through the joints of its claws and devours it gradually from the inside. After some time, a protuberance appears at the genital apparatus of the crab. At this stage the crab is no longer able to fix its claws, to reproduce, and it has also the duty to take care of the parasite eggs as if they were its.
This parasite affects all groups of marine animals, from the smallest (sponge) to the largest (cetaceans). This parasite has a way of sticking on the body of its guests (in the gills, in the outer tissues, in the organs or even in the eyes). As an exemple, the copepod is fixed on the eyes of the Greenland from its birth to its death. The parasite just pumps physiological fluids through a tube making the shark blind. For more information, read: "The 7 weirdest sharks."
This aquatic parasite lives in several hosts during its existence. We could say that this is a migratory parasit. It begins its life as an egg living in the belly of a bird. Once expelled with the feces, they are in turn consumed by a snail. This second host walks in the marshes where it's a desirable prey for the Killi (little fish). Once ingested, the parasite will infect its host and modify its behavior to get it captured more easily, for example making it resurface abnormally. A bird passing through will swallow the unfortunate prey and the cycle will run once again.
This tiny parasite mostly lives on of freshwater fish skin on which it is clung thanks to sixteen sharp hooks. In order to feed, the parasite releases a liquid that dissolves the skin of the fish. Then the parasite will sucks this « soup » made of mucus and dissolved skin. At the end, lesions on the skin cause secondary infections that can lead to the extinction of many fishes. This parasite is seriously considered by the authorities.
Here's a kind of parasite we know well: the long worm. The bothriocéphale has an uncommon existence. He is born with million of other eggs in the small intestine of a large mammal. Released in the feces of the host, it will then usually be swallowed by a crustacean, itself swallowed by a bigger predator that will be finally consumed by a mammal that can be a human being. As a piece of advise, it is recomended to cook freshwater fish flesh to avoid worms to survive. Swalloded, th worm can lead to severe complications such as anemia.
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