Clinging Jellyfish: The Facts

With the rise in rampant fear looming over the dime-sized clinging jellyfish’s sting to people recreating in the Shrewsbury and Navesink rivers that border the Rumson-Fair Haven peninsula, Fair Haven officials have issued a fact sheet advising people of the jellyfish’s characteristics and where they thrive.

Here it is …

The Clinging Jellyfish (Gonionemus vertens) is a small hydrozoan jellyfish about the size of a dime that can be found in bay and estuarine waters.

WHERE ARE THEY FOUND?

Clinging jelly sh are native to the Paci c Ocean. They were introduced to the eastern Atlantic Coast as early as 1894 in Woods Hole, Massachusetts, but can be found from Maine to North Carolina. Clinging jelly sh thrive in temperate regions, and can be found in sheltered shallow bay and estuarine waters where tides are not strong enough to dislodge them.

They prefer to cling to vegetation and other substrates (e.g. shells) during the day. They typically feed at night in the water column on small marine animals (zooplankton), but have been observed during the day. They are not typically found in coastal ocean waters.

HOW BIG DO THEY GET?

This is a small jelly sh that only grows to about 25 mm (1 inch) in diameter, but it can expand to about three inches in diameter. They have 60-90 tentacles that contain the nematocysts or stinging cells.

WHY ARE THEY IN NEW JERSEY WATERS THIS YEAR?

Although they have not been previously reported in New Jersey waters, their presence here may be a recent introduction, or they may have gone unnoticed in the past. They do not produce large populations as do some other jellyfish, but can be found in local areas in small to moderate numbers.

John Caroli
BCS Wealth Management