Once or twice a year, palolo swarm to the surface of the sea in great numbers. Samoans eagerly await this night and scoop up large amounts of this delicacy along the shoreline with hand nets. This gift from the sea was traditionally greeted with necklaces made from the fragrant moso’oi flower and the night of the palolo was and still remains a happy time of celebration. The rich taste of palolo is enjoyed raw or fried with butter, onions or eggs, or spread on toast.
Palolo is the edible portion of a polychaete worm (Palola viridis) that lives in shallow coral reefs throughout the south central Pacific, although they do not swarm at all of these locations. This phenomenon is well known in Samoa, Rarotonga, Tonga, Fiji, the Solomon Islands, and Vanuatu.
Palolo are about 12 inches long and live in burrows dug into the coral pavement on the outer reef flat. They are composed of two distinct sections. The front section is the basic segmented polychaete with eyes, mouth, etc., followed by a string of segments called the “epitoke” that contain reproductive gametes colored blue-green (females) or tan (males). Each epitoke segments bear a tiny eyespot that can sense light (that may be why islanders use a lantern to attract the palolo to their nets).
When it comes time to spawn, palolo will back out of their burrows and release the epitoke section from their body. The epitokes then twirl around in the water in vast numbers and look like dancing spaghetti. Around daybreak, the segments dissolve and release the eggs and sperm that they contain. The fertilized eggs hatch into small larvae that drift with the plankton until settling on a coral reef to begin life anew.
The swarming of palolo is a classic example of the coordinated mass spawning of a simple marine organism. The worms emerge from their burrows during a specific phase of the moon, but the actual date is a bit complicated. The swarms occur on the evenings of the last quarter moon of spring or early summer. In Samoa, this is seven days after the full moon in October or November. Swarming occurs for two or three consecutive nights with the second night usually having the strongest showing.
Palolo usually appear here in October, but sometimes in November or sometimes during both months. This difference is due to the fact that there are about 13 lunar months in one calendar year and the palolo use primarily the moon to time their spawning activity. If instead they always spawned every twelve lunar months, their time of spawning would occur earlier every year. After a few years, they would be spawning in August or July. In order to make up for this difference, the palolo will delay spawning in some years to the 13th lunar month.