Pacific Science Volume 33, Number 3, 1979

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Pacific Science is a quarterly publication devoted to the biological and physical sciences of the Pacific Region.

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    Penaeid Prawns in Fanga uta Lagoon, Tongatapu
    (University of Hawaii Press, 1979-07) Braley, Richard D.
    The penaeid prawns Penaeus semisulcatus and Metapenaeus ensis were surveyed in Fanga'uta Lagoon, Tongatapu, between July 1975 and August 1976. Catch rates indicate maximum abundance of P. semisulcatus from September to November and minimum abundance between January and February. Juveniles were found in March. Maximum abundance of M. ensis occurred from mid-October to January and minimum abundance from mid-February to mid-April. Spawning occurred outside the lagoon between January and March, and juveniles were found in the lagoon in late April. All areas of the lagoon show a similar pattern of catch rates. Catch rates of prawns were reduced by one-third during the light phase of the moon, and the full moon appears to be a factor associated with moulting in M. ensis.
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    A New Stenopodidean Shrimp (Decapoda, Natantia) from the Chatham Rise, New Zealand
    (University of Hawaii Press, 1979-07) Baba, Keiji
    A new stenopodidean shrimp, Spongicoloides novaezelandiae sp. nov., taken in a depth of about 1000 m in the Chatham Rise is described and illustrated. It is somewhat similar to the east Atlantic Spongicoloides evolutus (Bouvier), from which it is readily distinguished by the number of gills on the maxillipeds. The genus Spongicoloides Hansen, previously known only from the Atlantic, is recorded for the first time from New Zealand waters as well as from the Pacific.
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    A Biological Determination of the Taxonomic Status of Conus elisae Kiener in Hawaii
    (University of Hawaii Press, 1979-07) Perron, Frank E.
    A population of Conus pennaceus Born was examined at Hauula, Oahu, and was found to include darkly pigmented specimens referable to C. elisae Kiener. The larvae from an egg mass laid by one of the darkly pigmented cones were reared in the laboratory. Of seven surviving larvae, six developed the C. pennaceus color pattern, while one developed the. C. elisae pattern. It was concluded that Hawaiian cone shells which have in the past been referred to C. elisae are simply rare color forms of C. pennaceus.
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    The Biology of Hastula inconstans (Hinds, 1844) and a Discussion of Life History Similarities among other Hastulas of Similar Proboscis Type
    (University of Hawaii Press, 1979-07) Miller, Bruce A.
    Terebrid gastropods of the genus Hastula are found in great abundance on fine-sand beaches throughout the tropics. Hastula inconstans, a species common to surf beaches in the Hawaiian Islands, is the first hastula for which a complete life history is known. Hastula inconstans is a primary carnivore, preying exclusively on Dispio magna, a tube-dwelling, depositfeeding spionid polychaete. The gastropod lives just beyond the surf zone and exhibits well-developed adaptations that permit survival in this habitat. The broad, fleshy foot, used in anchoring the snail in the sand and in rapid reburrowing, is also highly modified as a "sail" which carries H. inconstans up and down the beach with the passage of waves. A highly specialized foregut contains long retractile labial and buccal tubes, which, combined with a poison bulb and radular teeth, rapidly sting, immobilize, and ingest prey. The snail lies buried in the sand when not feeding, but emerges when prey are detected by distance chemoreception. Nearby prey are reached by rapidly crawling over the sand surface, and prey at a distance are reached by using the foot to "sail" to their location. In either case, contact with the prey is first made by the propodium of the foot, rapidly followed by proboscis eversion. After contact is made, the prey is stabbed by a radular tooth held by the buccal tube, poison is injected into the wound, and engulfing of the worm begins. This entire sequence occurs between the passage of waves, and the snail usually reburrows to continue feeding before the next wave arrives. The sexes in Hastula inconstans are separate. Mating takes place above the sand while the animals are coupled and rolling freely in the surf, and approximately 40 spherical eggs are later deposited in a capsule covering a small piece of basalt. Larvae metamorphose when they are less than 1 mm in length and reach 3-5 mm in length by late spring. Individuals grow between 0.5 and 0.8 mm per month, reaching a maximum size of 34 mm, which suggests an average life-span of 3-4 years. Other hastulas with a proboscis nearly identical in structure to that of H. inconstans exhibit similar life history aspects, including habitat choice and prey specificity. It is suggested that feeding types may not only be useful as a diagnostic characteristic, but also in predicting basic life history aspects throughout the family.
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    A Comparison of Aspects of the Biology of Paranemertes peregrina (Nemertea) from Bodega Harbor, California, and Washington State
    (University of Hawaii Press, 1979-07) Roe, Pamela
    In Bodega Harbor, California, the nemertean Paranemertes peregrina spawns in June or July. Adults in the study area were small in comparison to worms found on two Washington mud flats. Population density of active worms averaged 7.38 worms/m2, with much variation due to time of day of low tides. Approximately 28 percent of the active population ate during the low tide periods that were sampled. Prey included spionids, nephtyids, polychaetes with capillary setae, and syllids (in decreasing importance). The number of prey families in the diet of California nemerteans was higher than in the two Washington mud flat populations and preferred nereid prey was less abundant in California and comprised less of the total diet of nemerteans there. Spionids were the major prey of California nemerteans in spring and summer; nereids were the major prey in fall and winter. In food preference tests, nemerteans showed negative responses to phoronids and lumbrinerids and positive responses to Nephtys caecoides. In comparison to three Washington populations, the population in Bodega Harbor was most similar to a rocky intertidal population and much different from two mud flat populations.
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