Fine structure of the eye of the New Zealand slugAthoracophovus bitentaculatus

1980 ◽  
Vol 94 (3) ◽  
pp. 225-239 ◽  
Author(s):  
Richard M. Eakin ◽  
Jean L. Brandenburger ◽  
G. M. Barker
Keyword(s):  
2021 ◽  
Vol 8 ◽  
Author(s):  
Joanna K. Cooper ◽  
Andrew R. Gorman ◽  
M. Hamish Bowman ◽  
Robert O. Smith

Seismic oceanography generally makes use of multi-channel seismic reflection data sourced by air gun arrays and long hydrophone streamers to image oceanographic water masses and processes—often piggybacking on surveys that target deeper geological features below the seafloor. However, due to the acquisition methods employed, shallow (upper 200 m or so) regions of the ocean can be poorly imaged with this technique, and resolution is often lower than desirable for imaging fine-structure within the water column. In 2012, we collected a set of higher-resolution seismic lines off the southeast coast of New Zealand, with a generator-injector airgun source and hydrophone streamer configuration designed to improve images of shallower water masses and their boundaries. The seismic lines were acquired with coincident expendable bathythermograph deployments which provides direct ties between physical oceanographic data and seismic data, allowing for definitive identification of the Subtropical Front and associated water masses in the subsurface. Repeat acquisition along the same transect shows significant temporal variability on the scale of hours, illustrating the highly dynamic nature of this important ocean boundary. Comparisons to conventional low-frequency seismic data in the same location show the value of high-resolution acquisition methods in imaging the near-surface of the ocean and allowing subsurface features to be linked to their expressions at the surface.


Author(s):  
John P. Jendrzejewski

Silicoflagellates are single-celled flagellated protists that secrete a relatively simple siliceous skeleton generally less than 100 microns in length. Silicoflagellate skeletons have been recovered from many types of marine deposits and have been utilized by geologists in biostratigraphic and paleoecologic analysis. The systematics of this group is established upon overall skeletal morphology. Recently, the importance of ornamentation found on the surface of these skeletons has been emphasized The surface of the silicoflagellate skeletons may be smooth, or ornamented with spines, warts, linear striations, ridges and complex reticulations (i.e. ridges of silica in which at least three converge to a point on the skeleton).


1986 ◽  
Vol 64 (3) ◽  
pp. 593-610 ◽  
Author(s):  
Øjvind Moestrup ◽  
Helge A. Thomsen

A new marine species of Chrysochromulina, C. apheles, is described from light and electron microscopy of a culture established from Danish coastal waters. The cells are among the smallest known in any species of Chrysochromulina, measuring ca. 4 μm in diameter. The general fine structure is illustrated and the structure of the haptonema and the flagellar apparatus is described in detail, based on serial sections. The flagellar root system, not previously examined in detail in any member of Chrysochromulina, is shown to consist of four microtubular roots, while cross-banded roots are lacking. Four cross-banded fibres were seen to interconnect the flagellar bases and the haptonema base. The haptonema belongs to the rather unusual six-stranded type. Two very similar looking types of small organic scales are present on the cell body. Unpublished data on the flagellar roots of the type species of Chrysochromulina, C. parva, are included. Chrysochromulina apheles is apparently cosmopolitan. It has presently been found in material from Denmark, Finland, England, Thailand, Australia, and New Zealand.


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