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| Registros recuperados: 51 | |
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| Spoel, S. van der. |
| Shell growth and size variation in populations of Diacria trispinosa Clio pyramidata, Cuvierina columnella, and Cavolinia gibbosa are studied. Attention is given to differences in the size variations of the four species caused by differences in their developmental biology. The reproductive cycle of Clio pyramidata forma lanceolata in the Bermuda Area is described and it is shown that there are more than one protandric hemaphrodite sexual cycles in one animal. The vertical migration of the four mentioned species is discussed. |
| Tipo: Article / Letter to the editor |
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| Ano: 1973 |
URL: http://www.repository.naturalis.nl/record/505038 |
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| Spoel, S. van der. |
| Studying the kidneys of the Common Porpoise and the Fin Whale it was found that there is a second venal system next to the normal venal system. The arterial and venal system as found in the kidneys of the dog are present in the kidneys of the Common Porpoise without typical differences but there is also a venal system situated outside the renculi which conducts the blood from the venae arcutae to the vene cava. This system is found in the kidneys of the Common Seal but here it is replacing the system of the vena renalis which it does not do in the kidneys of the Common Porpoise. In the kidneys of the Common Porpoise and the Fin Whale both the plexus which surround the pelvic cavity and the ureter are present and they show to be nearly similar to those... |
| Tipo: Article / Letter to the editor |
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| Ano: 1963 |
URL: http://www.repository.naturalis.nl/record/504544 |
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| Spoel, S. van der. |
| Biodiversity can be considered to be a human appreciation of the biological entity diversity. Diversity can be expressed numerically on the basis of taxa found, but it can also be expressed as the contribution of a specimen to the diversity, for which a formula is proposed. Diversity is the sum of the taxonomic or numerical diversity, and the ecological, genetical, historical, and phylogenetic diversity. Moreover, each group, or larger taxon, has its own characteristic diversity. These types of diversity are considered separately. One formula is tentatively proposed to calculate the overall diversity. Diversity in nature is variable, which is demonstrated in a diagram for comparison with societyinduced diversity changes. Diversity in the pelagic fluctuates... |
| Tipo: Article / Letter to the editor |
Palavras-chave: Biodiversity; Diversity calculation; Ecology; Pelagic; Phylogeny. |
| Ano: 1994 |
URL: http://www.repository.naturalis.nl/record/504018 |
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| Troost, D.G.; Spoel, S. van der. |
| In C. inflexa the mantle gland and its border show twenty-two bands. Differences in banding with C. longirostris are discussed. It appeared to be possible to discriminate the soft parts of juveniles in both species. Of special value for discrimination is the shape of the lateral appendages. The shells can be distinguished by the relative length of the caudal spine, which is longer in C. inflexa than in C. longirostris. Different developmental stages of C. longirostris are described and those of C. inflexa are added for comparison. While for the latter species the soft parts grow larger parallel with the increment of the shell, this is not the case in C. longirostris, due to the occurrence of minute stages and shedding of the caudal spine. The differences... |
| Tipo: Article / Letter to the editor |
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| Ano: 1972 |
URL: http://www.repository.naturalis.nl/record/505296 |
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| Bleeker, J.; Spoel, S. van der. |
| The medusa fauna of the mid North Atlantic Ocean between 24° and 55° N along approximately 30° W is studied. Two Hydromedusae new to science, Oceania tydemani and Annatiara lempersi, are described. The differences in fauna south and north of 42° N, and faunal borders near 50°, 48°, 45°, 35°, 30°, and 34°-37° N are discussed. The vertical distribution and for some species the diurnal migration and subtropical submergence are recorded. |
| Tipo: Article / Letter to the editor |
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| Ano: 1988 |
URL: http://www.repository.naturalis.nl/record/504150 |
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| Spoel, S. van der; Koperdraat, M.J.. |
| The Royal Dutch Navy participated in the cruises of the Cooperative Investigations in the Caribbean and Adjacent Regions (Cicar) from 1970 up to 1973 with H.Nl.M.S. “Luymes” and made 39 cruises. For general information on these cruises and preliminary results one is referred to the titles in the list of literature marked with a asterisk. Plankton collecting was executed by the ornithologists Drs. S. van Halewijn and Drs. D.M.C. Poppe and when ornithologists were not aboard the crew of the researchship did valuable work by continuing sampling. As plankton samples could in many cases not be correlated with the official Cicar Stations new numbers are added when possible. Confusion of the numbers is impossible as the new numbers are single numbers, the... |
| Tipo: Article / Letter to the editor |
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| Ano: 1974 |
URL: http://www.repository.naturalis.nl/record/506372 |
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| Registros recuperados: 51 | |
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