“What’s interesting about them is that they’re only parasitic in the juvenile stage. So they only feed when they are juveniles, and they go through three different juvenile stages -- one bigger than the other, each bigger than the other. And they look a little bit like, like ticks or fleas. They look very similar to, you know, to terrestrial blood feeding organisms.”

Paul Sikkel captured the juvenile marleyi at what researchers call a “cleaning station.” That is a place on the coral reef where big fish gather so smaller fish and shrimp can eat parasites that have joined to their skin. Parasites depend on other creatures for food and shelter. However, the adult male marleyi do not eat. They just mate and die.

Mr. Sikkel studied the species in a laboratory.

“Adult males look a little bit like bulldozers. They have square heads, and they have these pincers on their head and they are very cool-looking. And the females -- small head and a really big body that’s full of eggs.”

About eighty percent of all organisms found on coral reefs are parasites. Gnathiids are among the most important parasites in the oceans. Mr. Sikkel says the levels of gnathiids can show how healthy a reef is. In some waters, he is seeing fish more heavily covered with gnathiids -- marleyi among them.

“Too many gnathiids hurt the fish and too little coral, we think, leads to more gnathiids. So in a, in a nice healthy, you know, coral-rich environment, we don’t find very many gnathiids -- fish, you know, just get a few of them. But in areas where there isn’t much live coral, there are a lot more gnathiids and the fish get much heavier loads on them.”