Document Detail

Haemoglobin as a buoyancy regulator and oxygen supply in the backswimmer (Notonectidae, Anisops).
MedLine Citation:
PMID:  19043051     Owner:  NLM     Status:  MEDLINE    
Unlike all other diving insects, backswimmers of the genus Anisops can exploit the pelagic zone by temporarily achieving near-neutral buoyancy during the course of a dive. They begin a dive positively buoyant due to the large volume of air carried in their ventral air-stores, but rapidly enter a protracted period of near-neutral buoyancy before becoming negatively buoyant. This dive profile is due to haemoglobin found in large tracheated cells in the abdomen. Fibre optic oxygen probes placed in the air-stores of submerged bugs revealed that oxygen partial pressure (P(O(2))) dropped in a sigmoid curve, where a linear decline preceded a plateau between 5.1 and 2.0 kPa, before a final drop. Buoyancy measurements made by attaching backswimmers to a sensitive electronic balance showed the same three phases. Inactivating the haemoglobin by fumigating backswimmers with 15% CO eliminated both buoyancy and P(O(2)) plateaus. Oxygen unloaded from the haemoglobin stabilises the air-store during the neutrally buoyant phase after a decrease in volume of between 16% and 19%. Using measurements of air-store P(O(2)) and volume, it was calculated that during a dive the haemoglobin and air-store contribute 0.25 and 0.26 microl of oxygen, respectively.
Philip G D Matthews; Roger S Seymour
Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  The Journal of experimental biology     Volume:  211     ISSN:  0022-0949     ISO Abbreviation:  J. Exp. Biol.     Publication Date:  2008 Dec 
Date Detail:
Created Date:  2008-12-01     Completed Date:  2009-03-04     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0243705     Medline TA:  J Exp Biol     Country:  England    
Other Details:
Languages:  eng     Pagination:  3790-9     Citation Subset:  IM    
Ecology and Evolutionary Biology, School of Earth and Environmental Sciences, Darling Building, University of Adelaide, Adelaide, SA 5005, Australia.
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MeSH Terms
Air / analysis
Diving / physiology
Hemoglobins / physiology*
Insects / physiology*
Oxygen / physiology*
Partial Pressure
Swimming / physiology*
Water / chemistry
Reg. No./Substance:
0/Hemoglobins; 7732-18-5/Water; 7782-44-7/Oxygen

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