Megalodicopia hians in the Monterey submarine canyon: Distribution, larval development, and culture

• The exclusively deep-sea ascidian family Octacnemidae comprises several genera in which the oral siphon has hypertrophied to form two large lips which create an "oral hood" capable of capturing motile prey. Megalodicopia hians is typical of this carnivorous family and has been reported to prey upon small epibenthic crustaceans. Distribution of M. hians in the Monterey Canyon system (36 degrees 45'N, 122 degrees 00'W) (California) was determined with remotely operated vehicles. M hians was found sparsely to depths of at least 3800m throughout the canyon; however, abundance was greatest within the oxygen-minimum zone (400-800m). Eggs, sperm, and recently fertilized embryos were obtained repeatedly from adults returned to the laboratory in vivo, indicating that this species free-spawns routinely. Overall egg diameter (ovum plus chorion, plus follicle cells) was 175-190 mu m-considerably smaller than previously reported for this species. Embryonic development at temperature and oxygen concentrations equivalent to the oxygen-minimum zone was 2-4d and. embryos gave rise to typical phlebobranch "simple" tadpole larvae. Larval period was extremely variable, and settlement/metamorphosis occurred up to 3 months post-hatching. These results are discussed within the context of settlement-site selection and fertilization ecology of the species. (c) 2005 Elsevier Ltd. All rights reserved.

Ämnesord

NATURVETENSKAP  -- Biologi -- Ekologi (hsv//swe)

NATURAL SCIENCES  -- Biological Sciences -- Ecology (hsv//eng)

Nyckelord

marine invertebrate

ascidian

larvae

free-spawning

unmanned

vehicles

USA

California

Monterey Bay

PHLEBOBRANCHIA

ASCIDIANS

Publikations- och innehållstyp

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