On Themisto libellula in Baffin Island Coastal Waters
The gross internal anatomy, food habits, local summer ecology and breeding cycle of Themisto libellula Mandt are studied in material from Baffin island coastal waters obtained in 1939 and 1940. The chitinous proventriculus projects backwards into the cavity of the midgut and forms a "gastric ap...
Published in: | Journal of the Fisheries Research Board of Canada |
---|---|
Main Author: | |
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
Canadian Science Publishing
1946
|
Subjects: | |
Online Access: | http://dx.doi.org/10.1139/f42-050 http://www.nrcresearchpress.com/doi/pdf/10.1139/f42-050 |
id |
crcansciencepubl:10.1139/f42-050 |
---|---|
record_format |
openpolar |
spelling |
crcansciencepubl:10.1139/f42-050 2023-12-17T10:26:13+01:00 On Themisto libellula in Baffin Island Coastal Waters Dunbar, M. J. 1946 http://dx.doi.org/10.1139/f42-050 http://www.nrcresearchpress.com/doi/pdf/10.1139/f42-050 en eng Canadian Science Publishing http://www.nrcresearchpress.com/page/about/CorporateTextAndDataMining Journal of the Fisheries Research Board of Canada volume 6e, issue 6, page 419-434 ISSN 0015-296X General Medicine journal-article 1946 crcansciencepubl https://doi.org/10.1139/f42-050 2023-11-19T13:39:14Z The gross internal anatomy, food habits, local summer ecology and breeding cycle of Themisto libellula Mandt are studied in material from Baffin island coastal waters obtained in 1939 and 1940. The chitinous proventriculus projects backwards into the cavity of the midgut and forms a "gastric apparatus" which cuts off part of the wall of the anterior midgut from direct contact with the food. The gastric apparatus is strongly reminiscent of the peritrophic membrane in insects and the Onychophora. The food in the summer consists mainly of the smaller crustacean plankton; plant matter was also found in the gut. There is a high incidence of infection by a Gregarine parasite. The possible causes of the reduction in numbers of Themisto in the fjord waters in August are discussed; the reduction is tentatively referred to the agency of the outflowing surface current coupled with the habit of Themisto of seeking the surface waters. The breeding cycle is of the alternating, or two-phase type which has been recorded by the writer in other arctic planktonic forms. There is a breeding period in the early part of the year and perhaps another in the autumn. Article in Journal/Newspaper Arctic Baffin Island Baffin Themisto Themisto libellula Canadian Science Publishing (via Crossref) Arctic Baffin Island Journal of the Fisheries Research Board of Canada 6e 6 419 434 |
institution |
Open Polar |
collection |
Canadian Science Publishing (via Crossref) |
op_collection_id |
crcansciencepubl |
language |
English |
topic |
General Medicine |
spellingShingle |
General Medicine Dunbar, M. J. On Themisto libellula in Baffin Island Coastal Waters |
topic_facet |
General Medicine |
description |
The gross internal anatomy, food habits, local summer ecology and breeding cycle of Themisto libellula Mandt are studied in material from Baffin island coastal waters obtained in 1939 and 1940. The chitinous proventriculus projects backwards into the cavity of the midgut and forms a "gastric apparatus" which cuts off part of the wall of the anterior midgut from direct contact with the food. The gastric apparatus is strongly reminiscent of the peritrophic membrane in insects and the Onychophora. The food in the summer consists mainly of the smaller crustacean plankton; plant matter was also found in the gut. There is a high incidence of infection by a Gregarine parasite. The possible causes of the reduction in numbers of Themisto in the fjord waters in August are discussed; the reduction is tentatively referred to the agency of the outflowing surface current coupled with the habit of Themisto of seeking the surface waters. The breeding cycle is of the alternating, or two-phase type which has been recorded by the writer in other arctic planktonic forms. There is a breeding period in the early part of the year and perhaps another in the autumn. |
format |
Article in Journal/Newspaper |
author |
Dunbar, M. J. |
author_facet |
Dunbar, M. J. |
author_sort |
Dunbar, M. J. |
title |
On Themisto libellula in Baffin Island Coastal Waters |
title_short |
On Themisto libellula in Baffin Island Coastal Waters |
title_full |
On Themisto libellula in Baffin Island Coastal Waters |
title_fullStr |
On Themisto libellula in Baffin Island Coastal Waters |
title_full_unstemmed |
On Themisto libellula in Baffin Island Coastal Waters |
title_sort |
on themisto libellula in baffin island coastal waters |
publisher |
Canadian Science Publishing |
publishDate |
1946 |
url |
http://dx.doi.org/10.1139/f42-050 http://www.nrcresearchpress.com/doi/pdf/10.1139/f42-050 |
geographic |
Arctic Baffin Island |
geographic_facet |
Arctic Baffin Island |
genre |
Arctic Baffin Island Baffin Themisto Themisto libellula |
genre_facet |
Arctic Baffin Island Baffin Themisto Themisto libellula |
op_source |
Journal of the Fisheries Research Board of Canada volume 6e, issue 6, page 419-434 ISSN 0015-296X |
op_rights |
http://www.nrcresearchpress.com/page/about/CorporateTextAndDataMining |
op_doi |
https://doi.org/10.1139/f42-050 |
container_title |
Journal of the Fisheries Research Board of Canada |
container_volume |
6e |
container_issue |
6 |
container_start_page |
419 |
op_container_end_page |
434 |
_version_ |
1785577930419601408 |