Bugula fabellata is found on the lower surfaces and edges of horizontal submerged timbers in Eel Pond, at Woods Hole, Mass.; B. turrita is found in similar habitats in Vineyard Sound or on the rocks at Stony Beach. Colonies of B. turrita are about 30 cm. high, yellow in color, and composed of flat branches growing in spirals. The flesh-colored colonies of B. flabellata are slightly shorter and are composed of broad, flat branches, each of which contains three to seven rows of zooecia. Both species have stalked avicularia shaped like birds' heads. Ripe colonies can be recognized by the prominent ovicells.

At Woods Hole, these animals have been found to release larvae from the first or second week of June until November 1 (Grave, 1930).

A. Care of Adults: The animals should be provided with running sea water.

B. Methods of Observation: Early stages of development can be obtained only by dissection of the ovicells, but larvae are easily obtained. Breeding colonies should be collected on the afternoon of the day previous to that on which they will be used. If they are placed in fingerbowls of sea water and left overnight in front of a window, the larvae will be released some time between 5 and 10 A.M. the next morning. If the fingerbowl is left in a dark-room during the night, the larvae will not be released at dawn, but will be retained until the colony is exposed to light. However, this release of larvae in response to light decreases after noon. The released larvae, which gather at the lighted side of the dish, can be pipetted to fingerbowls or other receptacles where they will attach. After attachment, the larvae should be transferred to vessels provided with running sea water, if further development is desired.

A. Early Stages of Development: Taxonomic confusion makes it uncertain whether the species B. flabellata found at Woods Hole is identical with B. calathus, studied by Vigelius (1886). If the two species are identical, the animals are hermaphroditic, and the internally fertilized eggs are transferred to ooecia where development occurs. The cleavages are regular and equal as far as the 32-cell stage, producing a flat, two-layered plate of cells. Gastrulation is probably by epiboly, and further development leads to the formation of a rather degenerate free-swimming larva.

B. Later Stages of Development: The ciliated larvae of the two species of Bugula found around Woods Hole are almost spherical and measure approximately 180 microns. Larvae of both species have a stiff circle of cilia surrounding a convex apical organ on the pole which is carried foremost in swimming. The opposite pole is depressed and bears a central invagination called the internal sac. This depression extends up one side of the larva to the equator in the form of a glandular groove. At the apex of this groove is a tuft of long flagella (the vibratile plume). The lateral groove and the plume make up the so-called "pyriform organ." The larva of B. turrita has, in addition, four or six eyespots: two or four located on the anterior borders of the lateral groove, and two on the opposite side. When they are first released, the larvae are strongly attracted by light, but after two or three hours, they gradually become negatively phototropic. If they are left undisturbed, the larvae also show a moderate negative geotropism. After a swimming period of four to six hours, the larva attaches. A temporary attachment is first made by the lateral groove; then the internal sac is suddenly everted and fastened to the substrate. About an hour after fixation, the larva begins to elongate, and in four to eight hours the body cavity is visible and the first polyp begins to form. The primary zoid is completely formed in 24 hours. From this time on, secondary individuals are produced rapidly by asexual budding, until a large colony is formed. Sexual maturity is attained about one month after attachment.

Corrêa, D., 1948. A embriologia de Bugula flabellata. Universidade de Sao Paulo Boll a. Fact Fill, Ciên., e Let., Zool., 13: 7-73.