Pacific Science (1980), vol. 34, no. 3 © 1981 by The University Press of Hawaii. All rights reserved Reproduction and Larval Development of Typosyllis pulchra (Berkeley & Berkeley) (Polychaeta: Syllidae)l ALBERT E. HEACOX 2 ABSTRACT: The reproductive biology of Typosyllis pulchra from the coast of Washington has been investigated based on observations of animals in the field and stolonization in the laboratory by both field-collected and cultured animals. Like most Syllinae, T. pulchra reproduces by stolonization, i.e., each individual produces 3-4 posterior, detachable, gamete-bearing stolons during consecutive 30-day intervals. Although some regenerating segments are in­ corporated into the stolons, in this species new stolons consist primarily of stock body segments. Reproductive animals occur in the field from late January through July; maximum reproductive activity is between April and June. Long days apparently promote reproduction, but lunar synchronization of spawning could not be demonstrated. Larval development is described based on light and scanning electron microscopy. Fertilization is external; developing larvae settle within 75 hr. The development of cephalic structures (eyes and antennae) is precocious com­ pared to other Syllinae that have been studied, and the sequence of para­ podium formation is unusual. LITTLE INFORMATION IS AVAILABLE concern­ amica (Herpin 1925), Typosyllis variegata ing reproduction or larval development of (Cazaux 1969), and Typosyllis prolifera any syllid polychaete; there is almost none (Franke 1979). for species from the northeastern Pacific. This paper describes reproduction and de­ Most reports on western American syllids velopment in Typosyllis pulchra, based on are limited to descriptions of reproductive field observations on the coast of Wash­ individuals and contain little or no ad­ ington and laboratory spawning of collected ditional reproductive data (Pettibone 1954, and cultured animals. MacGinitie 1955, Pettibone 1963, Banse 1972). Brooding has been described in the exogonine Exogone lourei (Woodin 1974) MATERIALS AND METHODS and the eusylline Syllides japonica (Heacox and Schroeder 1978). Collection Larval development has been investigated in a number of syllids; many of these studies Typosyllis pulchra (Berkeley & Berkeley) concern brooding species of Exogoninae, was collected from the rocky intertidal, near Autolytinae, and Eusyllinae. All the Syllinae the Slip Point Light Station, Clallam Bay, studied have been European species: Washington, within the root-rhizome Typosyllis hyalina (Malaquin 1893), Syllis system of the marine angiosperm Phyllo­ spadix scouleri. Every 6-8 weeks, for a 1 This research was supported by The Lerner Fund period of 18 months, Phyllospadix samples for Marine Research and the Sigma Xi Research were collected, placed in plastic bags, packed Society. Manuscript accepted 19 May 1980. on ice, and transported to the laboratory in 2 Washington State University, Department of Zoology, Pullman, Washington 99163. Present address: Pullman, Washington, for sorting. Water Zoologisches Institut der Universitiit zu Koln, Weyertal temperature was recorded and samples for 119, 5 Koln 41, Federal Republic of Germany. salinity determination were taken at each 245 246 PACIFIC SCIENCE, Volume 34, July 1980 collection. Samples awaltmg sorting were with the exception of Dunaliella and kept in aerated plastic dishpans in artificial Phaeodactylum were macerated in a tissue seawater (Instant Ocean®, density 1.020, grinder and centrifuged before being added ASW) at 10 0 e. The syllids were sorted by to the cultures. Worms were routinely fed hand with the aid of a dissection microscope. once a week, and the water in the bowls was Animals were identified with Banse and changed 24 hr after feeding. Hobson (1974) and checked against the de­ Worms were determined to be reproduc­ scriptions of T. pulchra provided by Berkeley tive when gametes were observed in the pos­ and Berkeley (1948), Hartman (1968), and terior end or when signs of stolonization Banse (1972). (stolon eye spots; swimming setae) were pre­ sent. Animals showing signs of reproduction within 10 days of collection were considered Maintenance to have been reproductive in the field. Ten to fifteen individuals were kept in Reproductive individuals were separated out 4-inch covered fingerbowls with 150 ml and examined for stolon type, stolon seg­ ASW and a small amount of sand from the ment number, oocyte size in females, and original biotope. Animals were kept either at number of regenerating posterior segments. 8 ± 1°C with a 12L/12D light/dark cycle or The larval development was followed by at 10 ± 1°C with an 18L/6D light/dark cycle periodically anesthetizing larvae in 7.3 per­ (Hauenschild 1972). Forty watts of indirect cent MgCl 2 and observing with a compound fluorescent lighting were used to initiate the microscope. light cycle. After the first hour, a step in­ crease in illumination was provided by the addition of 120 watts of direct fluorescent Scanning Electron Microscopy lighting. Light intensity was also decreased in a similar fashion at the onset of the last Some larvae were placed on 0.45-j.!m mil­ hour of light to simulate periods of dawn lipore or O.I-j.!m nucleopore filters, covered and dusk, respectively (Gidholm 1969). In with another filter, put in a filter holder, addition, a 15-watt light bulb was on during treated with 1500 NF3 units/ml ASW ovine the dark cycle of the five consecutive days hyaluronidase for 30 min (Atwood, Craw­ corresponding to the natural full moon of ford, and Braybrook 1975) to remove each month. mucus, and fixed in 2.5 percent glutaral­ Polychaetes in culture have been main­ dehyde in 0.2 M phosphate buffer containing tained on a variety of natural and artificial 0.14 M NaCI (pH 7.4). The specimens were foods (Muller 1962, Goerke 1971, Hauen­ then rinsed in 0.2 M phosphate buffer with schild 1972, Dean and Mazurkiewicz 1975). 0.3 M NaCI (pH 7.4) and postfixed in 2.0 The following foods were offered: frozen percent OS04 in 1.25 percent NaHC03 (pH spinach (Akesson 1967); powdered alfalfa 7.5) (Cloney and Florey 1968). Larvae were (D. Reish, personal communication); frozen then dehydrated through increasing concen­ Artemia (Hauenschild 1972); Tetramin®, a trations of ethanol, placed in an Omar SPC commercial dried fish food (Reish, personal 900 critical-point device and critical-point communication); the green alga Dunaliella dried in CO2 (Anderson 1951). After coating (Dean and Mazurkiewicz 1975); the diatom with gold in a Technics V sputtering device, Phaeodactylum; and hyroid polyps (Hamond the specimens were examined with an ETEC 1974). Feeding trials were also made with VI Autoscan scanning electron microscope Tetra® squid flakes and the mussel Mytilus (SEM). californianus. The hydroid polyps Tubularia and Garveia were used in this study because of their abundance in the intertidal zone where T. pulchra was collected. All foods 3NF = National Formulary. ·8- .4eew ;; ; !ttl I eM UAt ii ; ¥@1:?ttl £A _ M NitA 5bf.!i1J1. -2& Reproduction and Larval Development of T. pulchra-HEAcoX 247 5 mm B 1 mm FIGURE I. Adult Typosyllis pulchra showing regions of stolon formation and detail of anterior end (parapodia not shown). A, adult T. pulchra (S" segments involved in forming the first stolon; S2' segments involved in forming the second stolon; S3' segments involved in forming the third stolon); B, detail of anterior end (Pv, proventriculus). .............!' • '1 ". 248 PACIFIC SCIENCE, Volume 34, July 1980 RESULTS immature animals (less than 50 segments, or 10 mm), many of which were probably over­ Description and Life Cycle looked during sorting. Water temperature in the field reached a low of 8°C in December. Adult Typosyllis pulchra have 76-110 se­ The water temperature gradually began to tigers and are 15-25 mm long and 0.5 mm increase in early March and reached a high wide, excluding parapodia and setae (Figure of 12°C in late July and August before be­ lA). Although Clallam Bay specimens fit the ginning its decline. During the peak repro­ general descriptions of Berkeley and Berke­ ductive period, water temperature was about ley (1948) and Banse (1972), they differ con­ 100e. sistently in some characteristics (Figure IE). For instance, the proventriculus begins in Stolon Formation setigers 9-11 and extends through 5-7 seg­ ments (rarely 8, Figure IE); Banse indicates Stolonization can first be recognized by a it is 8 or 9 segments long. The dorsal cirri are posterior color change-to blue or purple in slender and alternately long and short. Long females and to white or light pink in males­ cirri on midbody segments have 35-40 due to the accumulation of gametes. Stolons annuli, considerably fewer than the 50-70 consist of 22-30 setigers and have a chaeto­ recorded by Berkeley and Berkeley. Banse syllis head type (Malaquin 1893, Schroeder (1972) concludes that the "heavily pig­ and Hermans 1975) (Figures lA, 2). The mented papilla" of Berkeley and Berkeley is latter consists of a prostomial cleft, two pairs a small but distinct occipital flap. However, of eyes, a single pair of antennae, and a in Clallam Bay animals the pigmentation single pair of tentacular cirri. Laboratory­ may be almost completely lacking. Living produced and field-collected stolons are specimens vary from the "chocolate brown" similar in size. seen by Berkeley and Berkeley through In the laboratory, mature animals repro­ green-brown, bright green, blue-green, and duce by the sequential production of three or yellowish brown. Such variability occurs four stolons during consecutive 30-day peri­ even within the laboratory-reared offspring ods at 100e. Ten days after the release of the of a single pair of animals. previous stolon, gametes can again be seen Adults occur in the field throughout the in the 10-12 posteriormost segments; these year, although the percentage of adults and segments will be incorporated into the newly the number of reproductive individuals fluc­ forming stolon.