Why were 10,000 ‘penis fish’ found on Drakes Beach in California?

A viral tweet of "penis fish" washed up on Drake's Beach in California. (Bay Nature Magazine/Twitter)

POINT REYES NATIONAL SEASHORE – Thousands of long, brown cylindrical shaped creatures washed up in a beach in California.

The mysterious sighting of ‘penis fish’ or fat innkeeper worms were discovered after a recent storm on Drakes Beach on Dec. 6, according to Bay Nature. The same phenomenon has been reported elsewhere.

What is a ‘penis fish’?

The fat innkeeper worm, or Urechis caupo, is a type of spoon worm, identified by its spatula-shaped proboscis for feeding, grasping or swimming.

Where can you find fat innkeeper worms?

U. caupo, the scientific name of the fat innkeeper worm, is only found in North America from Southern Oregon to Baja. However, these worms are almost uniquely a California experience, biologist Ivan Parr wrote.

What is life like for fat innkeeper worms?

It is mostly dark and underground. Located a beach or mudflat, the worm digs a “U-shaped burrow extending a few feet in length but no wider than the worm itself,” Parr wrote. Fossil evidence suggest the existence of these creatures dating back 300 million years and some can live up to 25 years.

How did thousands of ‘penis fish’ end up on Drakes Beach?

Since these worms live right beneath the earth, strong storms are capable of destroying the intertidal zone, breaking apart the sediments and leaving the contents stranded on shore, Parr wrote.

Do people eat fat innkeeper worms?

In South Korea, fat innkeeper worms are known as “gaebul” or “dog genitals” and is considered a delicious treat, according to Heavy. The fish are described as chewy and sweet from marinating in salt water. Peak season for the fish is December to March.