The Pacific spiny humpback sucker’s nightmare begins with the teeth: needle-sharp, along the edge of bulbous lips. A single fin crowns the fish’s head like a mohawk, and pointed studs cover nearly every inch of its body, reminiscent of an armored car from a “Mad Max” movie.
But the nightmare soon passes: The Pacific spiny clot sucker is barely two inches long.
“Pacific spiny snot suckers are definitely one of the cutest fish you can find,” Karly Cohen, a Ph.D. candidate in biology at the University of Washington, said recently.
Ms. Cohen and her colleagues have discovered that the fish has an extremely curious evolutionary and life history. In a study published in December in the Journal of Morphology, the researchers looked at how Pacific spiny clumps develop such armor and how they use it.
The known range of the Pacific spiny humpbacks extends from the Washington State coast up through western Canada and Alaska, across the Bering Sea to eastern Russia and northern Japan. They live in waters several meters deep and can range in size between a golf ball and a human head.
In addition to resembling a spiky puffball, the lump sucker also has suckers on the bottom of its body, similar to those found on octopus tentacles. These evolved long ago from pelvic fins, Ms Cohen said, and allow the clot sucker — a terrible swimmer — to cling to rocks, coral and other surfaces and not be swept away by the tidal zone’s strong currents.
“Being a really round fish in a resilient environment is a tough task,” said Ms. Cohen.
The Pacific spiny humpback sucker is typically an ambush predator, sitting and waiting to suck up small fish, crustaceans, or other creatures that pass by. Its stationary lifestyle means it often serves as a platform for algae, which provide camouflage in the rocky environment, said Leo Smith, an ichthyologist at the University of Kansas who was not involved in the study.
The clumsy’s habit of staying put also allows the males to be stay-at-home dads. The females often lay their eggs in empty barnacles and the males aggressively guard them until they hatch.
Research by Ms. Cohen and her colleagues, and recently accepted in the Journal of Morphology, found that male clots also fluoresce bright red. This can help them hide while babysitting eggs; the algae growing on the barnacles fluoresce in the same color as the fish.
The fry, once hatched, sink to the seabed and grab something with their fully developed suckers. “They just stay there for a while, like, ‘This is my safe place, here I go,'” said Ms. Cohen.
The researchers performed CT scans on clumps they captured off the coast of the University of Washington’s Friday Harbor Laboratories on San Juan Island between Canada’s Vancouver Island and mainland Washington state. They found that the scales are made of enamel and are not fish scales at all, but odontodes. “They come from teeth,” said Ella Woodruff, a student at Carleton College in Minnesota and author of December’s study.
The study found that Pacific spiny humpback suckers start their lives with harnesses only around their mouths, where teeth would be. As the fry grow, the odontodes spread to the tail, like a lumpy version of wisdom teeth. The armor protects them from predators and the tumultuous environment of the intertidal zone, where crashing debris can wreak havoc on an unprotected softball.
“It protects their bones from secondary infections from lying around,” said Dr. Smith, and the plates grow back as they fall off, adding insurance and flexibility.
Normally, full gear would be a problem for a clumsy swimmer. But enamel is lighter than other types of bone, so it doesn’t weigh much, Ms Cohen said.
dr. Smith said the new study helped explain why the armor of the Pacific spiny humpback sucker is so different from that of other animals in the intertidal zone, and why the creature looks so strange.
“These things are like Scooby-Doo villains,” he said.