Tidepool Tim says,  “Tubularia hydroids are plankton feeders and so do very well in the summer and fall months here in Cobscook Bay. They are kind of a scourge for lobstermen as they sometimes cover their traps with their growth, choking off the water flow thru the trap.  Traps, lines, and buoys are all affected. we find our best colonies on dock floats. These polyps grow quickly and eventually release sperm to fertilize their eggs. Nudibranchs love to eat the 'heads' of these, leaving only the stems behind.”