Dr Gill Mapstone PhD

Gill Mapstone
  • Scientific Associate - Invertebrates
  • Life Sciences department
  • Invertebrates
Natural History Museum
Cromwell Road


Positions held

  • Scientific Associate, The Natural History Museum, 2001-present
  • Visitor, The Natural History Museum, 1992
  • Visiting Scientist, University of Calgary, Alberta, Canada, 1989
  • Guest Biologist, Nationaal Natuurhistorisch Museum, Leiden, The Netherlands, 1987
  • Part-time Lecturer, Brooklands Technical College, Weybridge, Surrey & Strodes Sixth Form College, Egham, Surrey, 1982
  • Demonstrator, Department of Zoology, La Trobe University, Melbourne, Australia, 1975
  • Lecturer, Brooklands Technical College, Weybridge, Surrey, 1971



  • PhD Zoology, University of Reading, UK, 1969
  • BSc (Hons), Zoology, University of London, UK, 1966


  • Taxonomic editor of WoRMS database (Siphonophora), 2007-present
  • Associate editor of ERMS website (Siphonophora), 2004-2007
  • Council member of the Ray Society, London, 2003-present
  • Fellow of the Linnean Society of London, 1996-present
  • Peer review of siphonophore systematics papers for international journals

Research interests

Morphology and systematics of siphonophores

Siphonophores are complex polymorphic pelagic gelatinous cnidarians, sometimes known as ‘string jellies’. At present the group comprises about 170 species.

Habitat and life cycle

Siphonophores are marine and typically live offshore below the surface layer. They are fragile and break up easily when disturbed, passing their entire life cycle in the water column, without a benthic stage.

These important pelagic predators feed on zooplankton, particularly copepod crustaceans, and also sometimes on fish larvae and young food fishes. When conditions are suitable, they can reproduce rapidly and may occasionally become the dominant predator.


Most siphonophore species have two or more swimming bells – the nectophores – for propulsion, often on a stem; this stem and its bells form the nectosome.

Attached to the nectosome is the siphosome, or main stem, with numerous iterative units - the cormidia – along its length. A cormidium contains zooids for feeding (gastrozooids), others for buoyancy (bracts) and yet others for reproduction (gonophores).

Gastrozooids are muscular tubes attached to the stem at one end and with a mouth opening at the other end; each gastrozooid bears a single tentacle for prey capture.

Complex stinging batteries arise on side branches of each tentacle, and these contain a very large number of nematocysts which immobilize the prey. The gastrozooid mouth then engulfs the prey and enzymes are secreted onto it from the glandular walls of the gastrozooid.

In one group of siphonophores, the physonects, digestion is completed inside reduced gastrozooids known as palpons.

Species identification and variation

Nectophores are important for species identification. Bracts can also be diagnostic, and the complex stinging batteries on the gastrozooid tentacles of physonects particularly so.

Siphonophore species vary in size from small diphyid calycophorans, such as Muggiaea atlantica with a nectophore only 2-3 mm long, to large physonects with a number of nectophores and a long trailing siphosome up to 30 metres in length.


  • Mapstone GM ( 2013 ) Global Diversity and review of Siphonophorae (Cnidaria: Hydrozoa). This article is being prepared for submission to Plos One, as part of the Plos Collections, PLos One The World Register of Marine Species. in preparation .
  • Mapstone GM, Ljubenkov JC. ( 2013 ) New observations on Dromalia alexandri Bigelow, 1911, a rhodaliid physonect siphonophore from southern Californian waters. Marine Ecology 34 (1) : 96-112 . Marine Ecology | doi:10.1111/maec.12029
  • Hiscock, K., Mapstone, G.M., Conway, D.V.P. and Halliday, N. ( 2010 ) Occurrence of the physonect siphonophore Apolemia uvaria off Plymouth and in south-west England. Marine Biodiversity Records 3 : 1-4 . doi:10.1017/S1755267210000205.
  • Mapstone, GM. ( 2004 ) First full description of the large physonect siphonophore Halistemma amphytridis (Lesueur & Petit, 1807).   Hydrobiologia 530/531 : 231-240 . doi:10.1007/s10750-004-2677-1
  • Mapstone, GM. and Pugh, PR. ( 2004 ) Case 3309.Rosacea Quoy & Gaimard, 1827: proposed conservation of usage (Cnidaria, Siphonophora); Desmophyes annectens Haeckel, 1888 and Rosacea plicata Bigelow, 1911: proposed conservation. Bulletin of Zoological Nomenclature 61(3) : 149-153 . Bulletin of Zoological Nomenclature
  • Mapstone, GM. ( 2003 ) Redescriptions of two physonect siphonophores, Apolemia uvaria (Lesueur, 1815) and Tottonia contorta Margulis, 1976, with comments on a third species Ramosia vitiazi Stepanjants, 1967 (Cnidaria: Hydrozoa: Apolemiidae). Systematics and Biodiversity 1(2) : 181-212 . doi:10.1017/S1477200003001166
  • Mapstone, GM. ( 1997 ) Bargmannia lata, an undescribed species of physonect siphonophore (Cnidaria, Hydrozoa) from Canadian Pacific waters. In Commemorative volume for the 80th birthday of Willem Vervoort. Edited by: J.C.den Hartog, A.C. van Bruggen, P.F.S. Cornelius and L.P. van Ofwegen. Zoologische Verhandelingen 323: i-xii : 141-147 .
  • Mapstone, GM and Arai, MN. ( 1992 ) Abundance and vertical distribution of siphonophores (Cnidaria) from the central Strait of Georgia, British Columbia, during spring and summer. Contribution to Natural Science 15 : 1-8 .