Rubbery Bryozoans Wash Up at Slaughter Beach

Colonial marine invertebrates appeared in large numbers on the Delaware Bay shoreline this fall.

Updated on Nov. 7, 2026 in Aquariums

Clusters of rubbery brown-tan bryozoan colonies lie in a wet sand wrack line on a Delaware Bay beach at low tide. — Large numbers of rubbery bryozoans, identified as Alcyonidium hauffi, washed up at Slaughter Beach on Delaware Bay this fall, state officials and researchers said. AI Illustration. Upload story photo >

Large numbers of rubbery bryozoans washed up at Slaughter Beach this fall. The colonial invertebrates, identified as Alcyonidium hauffi, are not plants or algae and are not dangerous to humans or pets.

Why it matters

Bryozoans attach to hard surfaces on the bottom of Delaware Bay and are typically dislodged by wind and waves on the shallow continental shelf. Their appearance on beaches reflects storm-driven movement of bottom-dwelling organisms rather than a direct hazard to residents or visitors across Delaware.

The species involved is Alcyonidium hauffi, a colonial animal made of many microscopic individuals that feed by filtering particles from the water. No counts of the deposited bryozoans were reported, and their frequency compared with prior years is not yet documented.

The players

Alcyonidium hauffi

A species of colonial marine bryozoan identified as the rubbery bryozoan found on Slaughter Beach.

The details

Each rubbery structure is built from many microscopic animals that filter particles from the water column and attach to hard substrate on the bottom of the Delaware Bay. Wind and waves dislodge them from rocks or algae, and higher tides deposit them on the beach, where they often break apart; they can carry salt and bacteria if eaten.

Late spring or early summer: Horseshoe crabs spawn on Delaware Bay beaches.
Fall 2026: Rubbery bryozoans washed up in large numbers at Slaughter Beach.

Seasonal Patterns

Rubbery bryozoans wash up on Delaware Bay beaches during the same seasonal window that horseshoe crabs spawn along the shoreline, which places the fall deposition within the bay's annual coastal cycle. The extraction provides no historical records to determine whether this fall's volume exceeds prior seasons.

Residents and visitors on Delaware beaches can see these colonial animals on the shoreline, but they pose no danger to people or pets. Eating them is not advised because they can contain lots of salt and bacteria.

The takeaway

Rubbery bryozoans are harmless colonial animals that washed up on Slaughter Beach, so beachgoers can observe them without concern while avoiding eating them.