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The Pacific prickly lump-sucker’s nightmare begins with teeth: needle-sharp, covering the edge of swollen lips. A single fin crowns the fish’s head like a mohawk, and spikes covering nearly every inch of its body resemble an armored car from a “Mad Max” movie.
But the nightmare passes quickly: The Pacific prickly lump is almost three inches long.
Ph.D. “Pacific spiny balls are definitely one of the cutest fish you can find,” said Karly Cohen. Biology candidate at the University of Washington, said recently.
Ms. Cohen and her colleagues discovered that the fish has an extremely curious evolutionary and life history. Inside study Published in the Journal of Morphology in December, researchers examined how Pacific spiny pellets developed and used such armor.
Known Pacific spiny pellets extend from the coast of Washington State to western Canada and Alaska, along the Bering Sea to eastern Russia and northern Japan. They live in waters several feet deep and can range in size from a golf ball to a human head.
In addition to resembling a spiny balloon, the tuber sucker has suckers on the underside of its body, similar to those of octopus tentacles. Ms Cohen said these evolved from pelvic fins a long time ago, allowing the lump sucker – a fearsome swimmer – to stick to rocks, corals and other surfaces and not be swept away by the strong currents of the tidal zone.
“Being a truly round fish in a leaping environment is a challenge,” said Ms. Cohen.
The Pacific spiny-punch is typically an ambush predator that sits and waits to suck in small fish, crustaceans, or other creatures that pass by. Leo Smith, an ichthyologist at the University of Kansas who was not involved in the research, said the stable lifestyle means it serves as a platform for algae that provide camouflage around the reef.
The tuber’s habit of staying where it is also allows men to be stay-at-home dads. Females usually lay their eggs in empty mussel shells and males aggressively guard them until they hatch.
Research by Ms. Cohen and her colleagues, recently published in the Journal of Morphology, found that male pellets also emit bright red fluorescence. This can help them hide while babysitting; Algae growing on mussels fluoresce the same color as fish.
After hatching, the fry sink to the seafloor and cling to something with their fully developed suction cups. “This is my safe spot, like this is where I go, they get stuck there for a while,” said Ms. Cohen.
The researchers performed CT scans of the pellets they caught off the shores of Washington University’s Friday Harbor Laboratories on San Juan Island, between Canada’s Vancouver Island and mainland Washington State. They found that the scales were made of enamel and were odontodes, not fish scales. “They come from the teeth,” said Ella Woodruff, an undergraduate at Carleton College in Minnesota and author of the December study.
The study found that Pacific spiny ball pups begin their lives with only armor around their mouths, where they will have teeth. As the pups grow, the odontodes spread out towards the tail like a clumped version of wisdom teeth. The armor protects them from predators and the turbulent environment of the intertidal zone where collapsing debris can severely damage an unprotected softball.
Dr. “It protects your bones from secondary infections,” Smith said, and if the plates fall out they regrow, adding insurance and flexibility.
Normally a full set of armor poses a problem for a clumsy swimmer. But enamel is lighter than other types of bone, so it doesn’t make them too heavy, said Ms. Cohen.
Dr. Smith said the new study helps explain why the Pacific prickly fist’s armor is so different from other animals in the tidal zone, and why the creature looks so strange.
“These things are like Scooby-Doo villains,” he said.
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