Dr Gill Mapstone PhD

Biography

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

Qualifications

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

Professional

• 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.

Morphology

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.

Publications