Beach walk takes horrifying turn after woman spots something scattered in the sand

The discovery of so many sharks at once is a rare occurrence, shark ecologist Mike Heithaus told Fox News Digital.

"This is definitely something that's pretty rare, to see that many sharks washed up on the beach," said Heithaus, dean of Florida International University's College of Arts, Sciences & Education. 

The beachgoer, Michelle Greenling, told CBS Philadelphia she found 29 dead sharks between 29th and 39th streets along the shore.

The beachgoer described the sight as "definitely concerning."

"I was concerned about the water. I was concerned about the sharks," she said.

Fox News Digital reached out to Greenling for further comment.

While a toxin might initially appear to be one possible explanation, he said he would expect other marine species to have been affected as well.

"The fact that there aren't lots of other different kinds of animals washing up at the same time suggests it's not some kind of pollution or toxin in the environment," said Heithaus, who was not involved in the discovery or analysis.

"If I had to make a guess, probably something happened to them, and they were caught, but [they] weren't what people were looking for, and so they got discarded."

"We've learned enough that we can monitor water quality and figure out what's going on ahead of these events happening so we can make interventions when we might have to," he said.

"But, you know, in this case, it looks like it was probably something else."

Heithaus also advised beachgoers who encounter large numbers of dead marine animals to alert local authorities or wildlife officials.

Dogfish typically have a lifespan of 35 to 40 years, according to NOAA Fisheries' website.

"Like all sharks, dogfish grow slowly, mature late in life and live a long time," the site states.