Publication Date:
2021-06-24
Description:
Ninety six gonatid cephalopod specimens (Oegopsida: Gonatidae) from the University of Amsterdam Mid-North Atlantic Plankton Expeditions were analyzed and two species were identified: Gonatus steenstrupi (Kristensen 1981) and Gonatusfabricii (Lichtenstein 1818). Gonatids were collected only in spring and summer, despite sampling in autumn and winter. This paper describes aspects of their development and reports their geographical distribution in the central North Atlantic Ocean. Chromatophore patterns were the most consistently useful characters for distinguishing between the species. Among 34 measurements, Tentacle Length (TtL) relative to Dorsal Mantle Length (ML) and number of suckers on Arms I-IV were useful for distinguishing specimens 〉13 mm ML. Both species develop hooks from suckers on the arms and tentacular clubs at ML 〉 20 mm. Subtle differences were noted in the morphology of the funnel pads except in the smallest specimens. Specimens of G. steenstrupi 〉20 mm ML were collected at greater depths (250 to 995 m) than the smaller specimens (found at depths 〈200 m). Our data suggest that 20 mm ML is the point of transition between paralarvae and juveniles of G. steenstrupi, because specimens larger than 20 mm ML have well defined hooks, and a juvenile vertical distribution is established.
Type:
Article
,
PeerReviewed
Format:
text
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