2.50
Hdl Handle:
http://hdl.handle.net/10547/621815
Title:
Nymphon (Pycnogonida) in the Eastern Arctic
Authors:
Cranmer, Gary John
Abstract:
Nymphon is the largest genus of Pycnogonida reaching its greatest diversity in the Polar regions. A revision of the genus within the Eastern Arctic has proved necessary due to the numerous nomenclatural complexities which have accumulated in the literature since its last major revision by Sars in 1891. This has been achieved using multivariate analyses involving the measurement of over 1500 specimens. Fifteen species are now recognized from the area and each has been redrawn and redescribed. It has not proved necessary to propose any new species. Two distinct sub-groups are found within the genus in this area, differing in leg morphology and reproductive strategy. The first group, exemplified by Nymphon stromi, has a leg morphology suited to walking or striding. A large number of lightly yolked eggs are typically produced and the larvae spend only a short period of their development on the male ovigers before they disperse. The other group, exemplified by Nymphon hirtipes, has a leg morphology more suited to clinging. Fewer eggs are produced but these are richer in yolk and the male overwinters with the larvae which are lost only when metamorphosis is nearly complete. These interspecific differences have been discussed and it is thought that they may enable direct competition to be avoided by the exploitation of different facets of the same environment. In addition, differences in the musculature have been discussed for species within Nymphon and for the Pycnogonida generally. The male ovigers of all species examined show various adaptations which increase the surface area compared with that of the female. These modifications have been discussed and are shown to afford a greater area for attachrnent of the maturing egg masses. A histological examination of the internal structure of the femoral cement glands of Nymphon hirtipes has revealed that the adult males have a broad band of glandular tissue lying under the epidermis whereas specimens in the final larval stage have little or none. The life-cycle of Nymphon hirtipes is postulated, showing the species to take between two and a half and three years to attain maturity. It breeds only once, during its final summer. This is compared with existing knowledge of the life cycles of shallow and tropical water species.
Citation:
Cranmer, G.J. (1982) 'Nymphon (Pycnogonida) in the Eastern Arctic'. PhD thesis. Luton College of Higher Education.
Publisher:
University of Bedfordshire
Issue Date:
Jul-1982
URI:
http://hdl.handle.net/10547/621815
Type:
Thesis or dissertation
Language:
en
Description:
A thesis submitted to the Council for National Academic Awards in partial fulfilment of the requirements for the degree of Doctor of Philosophy.
Appears in Collections:
PhD e-theses

Full metadata record

DC FieldValue Language
dc.contributor.authorCranmer, Gary Johnen
dc.date.accessioned2016-11-07T13:24:04Z-
dc.date.available2016-11-07T13:24:04Z-
dc.date.issued1982-07-
dc.identifier.citationCranmer, G.J. (1982) 'Nymphon (Pycnogonida) in the Eastern Arctic'. PhD thesis. Luton College of Higher Education.en
dc.identifier.urihttp://hdl.handle.net/10547/621815-
dc.descriptionA thesis submitted to the Council for National Academic Awards in partial fulfilment of the requirements for the degree of Doctor of Philosophy.en
dc.description.abstractNymphon is the largest genus of Pycnogonida reaching its greatest diversity in the Polar regions. A revision of the genus within the Eastern Arctic has proved necessary due to the numerous nomenclatural complexities which have accumulated in the literature since its last major revision by Sars in 1891. This has been achieved using multivariate analyses involving the measurement of over 1500 specimens. Fifteen species are now recognized from the area and each has been redrawn and redescribed. It has not proved necessary to propose any new species. Two distinct sub-groups are found within the genus in this area, differing in leg morphology and reproductive strategy. The first group, exemplified by Nymphon stromi, has a leg morphology suited to walking or striding. A large number of lightly yolked eggs are typically produced and the larvae spend only a short period of their development on the male ovigers before they disperse. The other group, exemplified by Nymphon hirtipes, has a leg morphology more suited to clinging. Fewer eggs are produced but these are richer in yolk and the male overwinters with the larvae which are lost only when metamorphosis is nearly complete. These interspecific differences have been discussed and it is thought that they may enable direct competition to be avoided by the exploitation of different facets of the same environment. In addition, differences in the musculature have been discussed for species within Nymphon and for the Pycnogonida generally. The male ovigers of all species examined show various adaptations which increase the surface area compared with that of the female. These modifications have been discussed and are shown to afford a greater area for attachrnent of the maturing egg masses. A histological examination of the internal structure of the femoral cement glands of Nymphon hirtipes has revealed that the adult males have a broad band of glandular tissue lying under the epidermis whereas specimens in the final larval stage have little or none. The life-cycle of Nymphon hirtipes is postulated, showing the species to take between two and a half and three years to attain maturity. It breeds only once, during its final summer. This is compared with existing knowledge of the life cycles of shallow and tropical water species.en
dc.language.isoenen
dc.publisherUniversity of Bedfordshireen
dc.rights.urihttp://creativecommons.org/licenses/by-nc-nd/4.0/*
dc.subjectC161 Marine Biologyen
dc.subjectArcticen
dc.subjectpycnogonidsen
dc.titleNymphon (Pycnogonida) in the Eastern Arcticen
dc.typeThesis or dissertationen
dc.type.qualificationnamePhDen_GB
dc.type.qualificationlevelPhDen
dc.publisher.institutionUniversity of Bedfordshireen
This item is licensed under a Creative Commons License
Creative Commons
All Items in UOBREP are protected by copyright, with all rights reserved, unless otherwise indicated.