31. Scattered colonies of " Alcyonium digitatum " are occasionally present along with the hydroid " Bougainvillia muscus ". 32. It attaches to kelp, hard objects ( rocks, oil well rigs ) or invertebrates such as hydroids using byssal threads. 33. "Doto escatllari " was found associated with small hydroids of the family Sertulariidae; these are probably its prey. 34. In the sea mounts where the orange roughy is hunted, there were once sea fans, black corals, hydroids , invertebrates. 35. They remain attached to the hydroids or break off to be passively drifted away; in a few, the gonophores are naked. 36. It breeds in mid-winter, the eggs being laid amongst hydroid growths on the sea bed, and on stony ground. 37. These polyps develop over a few days into tiny 1 mm medusae, which are liberated and swim free from the parent hydroid colony. 38. The only character of " Calymperastrum " that does not occur in the Calastraceae is the presence of a leaf hydroid strand. 39. As a result, the hydroids have become one of the chief competitors of the commercial fish and may threaten their survival, Bollens said. 40. Each apparent individual " Velella velella " is in fact a hydroid colony, and most are less than about 7 cm long.
