Bursatella Leachii Research Articles

Mucous trail following in 2 intertidal nudibranchs

Gastropods are generally known to be able to follow mucous trails. They follow the trails of their own for homing (McFarlane 1981; Chelazzi et al. 1987), of the same species for mating (Townsent 1974) or of other species for predation (Paine 1963; Gonor 1967). But according to Cook (1977), "trail following may be widespread [but] it need not necessarily be a general feature of a gastropod's normal behavioural repertoire." Trail-following behavior in opisthobranchs, especially for mating, has been referred to in only a few studies (Hadfield & SwitzerDunlap 1984) and not certified experimentally. For example, Stylocheilus longicauda (SwitzerDunlap & Hadfield 1979) and Bursatella leachii pleii (Lowe & Turner 1976) were observed to follow conspecific trails in the field. Todd (1979) considered that Onchidoris bilamellata might find mates by following trails, but the results of his laboratory tests were inconclusive. Dendrodoris nigromaculata and D. nigra are common sponge feeders in the intertidal zone of southern Japan. They are annual species, as is common among nudibranchs, and are sometimes observed in aggregations during the spring mating season. As nudibranchs are simultaneous hermaphrodites, they need not distinguish the sex of other individuals for mating. In the present study, I examined whether they utilize water-borne substances of the same species or mucous trails to find their mate.

Behavior Patterns of the Aplysiid Gastropod Bursatella leachii in Its Natural Habitat and in the Laboratory

The behavior of the ragged sea hare, Bursatella leachii pleii Rang, was observed in its natural habitat and in captivity. An indication of the seasonal availability of Bursatella in Puerto Rico was obtained by making multiple observations at a single site. The behavior patterns of Bursatella in the field were indicative of a daily rhythm. They tended to be found in groups at sunrise and as isolated individuals in the afternoon. They were observed to assemble following sunset and to disperse in the morning. Certain aspects of this rhythmic pattern of behavior persisted in animals held in the laboratory, where copulation was the most common behavior in the morning and feeding-related activities became more prevalent in the afternoon. Specific behaviors related to autonomic function (respiration and digestion) were also observed and quantified. It is proposed that the rich behavioral repertoire exhibited by B. leachii, and the ease with which these animals are observed in their native habitat, provide favorable systems for studying neuronal mechanisms involved in the organization and evolution of complex behavior.

Amino acid sequence of myoglobin from the molluscBursatella leachii

The complete amino acid sequence of myoglobin from the triturative stomach of gastropodic mollusc Bursatella leachii has been determined. It is composed of 146 amino acid residues, is acetylated at the N-terminus, and contains a single histidine residue at position 95 which corresponds to the heme-binding proximal histidine. The E7 distal histidine, which is conserved widely in myoglobins and hemoglobins, is replaced by valine in Bursatella myoglobin. The amino acid sequence of Bursatella myoglobin shows strong homology (73-84%) with those of Aplysia and Dolabella myoglobins.

Spermatocyte Chromosomes in Some Species of the Family Aplysiidae (Gastropoda, Opisthobranchia)

SUMMARYCounting spermatocyte bivalents, we have determined the haploid number n = 16 for Aplysia depilans and A. punctata, and n = 17 for A. limacina. We have confirmed n = 17 for Bursatella leachii. Male diakinetic bivalents are probably chiasmatic in all the species examined. The orders Nudibranchia and Notaspidea, possessing haploid values of 13 and 12 chromosomes respectively, seem to be more evolved than the other orders of the sub-class Opisthobranchia.

Defensive chemistry of Navanax and related opisthobranch molluscs

The strategies of chemical defense in marine opistho— b±anchs are reviewed, emphasizing the accumulation of secondary compounds through the food chain and the production of defensive compounds in specialized glands. The structures of several new compounds from Aplysia brasiliana, Bursatella leachii, and Navanax inermis are presented.