Story highlights A scientist says photos of a goblin shark also show deep sea isopods

The creatures are common, but it's rare to spot them, he says

The marine biologist says it's possible the creatures were eating a rare deep sea meal

"They have to be able to store all this food. ... They don't know when they will feed again"

Photos of the gruesome-looking goblin shark a fisherman accidentally caught last month drew attention as scientists caught a rare glimpse of the deep sea creature.

But wait, there's more.

Now another marine species shown in the photographs has scientists talking.

Many deep sea isopods showed up in the pictures of what fisherman Carl Moore caught in his net, said Andrew Thaler, a marine biologist in California.

You've probably never seen one. "Imagine a pill bug the size of a house cat," Thaler said.

The creatures, which can grow up to 20 centimeters, are common in the deep sea, Thaler said, but spotting them is rare because they're usually very spread out.

Click to expand: Deep sea isopods, which look like giant pill bugs, can also be seen in the photos.

"I've never seen that many in one place at the same time before," he said.

So why would there be so many gathered together?

Maybe it was dinner time.

"Food in the deep sea is very rare. That is one of the defining characteristics of the deep sea. There is no sunlight, so there are no plants for the most part," Thaler said.

So, when something large like a whale dies at sea, he said, scavengers swarm around it.

"They can go and gorge on a carcass and survive for months," he said. "They have to be able to store all this food in their body because they don't know when they will feed again."

That means the reason Moore caught the rare goblin shark could be because it and other deep sea creatures were feasting on something, Thaler said.

The goblin shark Moore caught last month was only the second member of the species ever caught in the Gulf of Mexico, and the first since 2000, shark expert John Carlson said.

Moore, 63, of Townsend, Georgia, estimates the shark was 18 to 20 feet long. He caught it on April 19, about halfway through an 18-day fishing trip.

The shark was still alive, so Moore released it after snapping photos.