David Shale / Detail of deepsea Sea pen (Pennatulacea) from coral seamount, Indian Ocean, December 2011

Alex Mustard / 2020VISION / Phosphorescent Seapen (Pennatula phosphorea) extends out of the muddy seabed in the calm waters of the upper reaches of a Scottish sea loch. Loch Duich, Ross and Cromarty, Scotland, UK, April

Juergen Freund / Caretaker transfers live fish in fish pens of Groupers / Coral trout, Live Reef Fish Trade, Tampakan, Kudat Bay, Sabah, Borneo, Malaysia, June 2009.

Juergen Freund / Sea pens (Virgularia sp) on sandy seabed, Palawan, Philippines.

Tim Laman / Grouper holding pens, destined for the live fish trade to Hong Kong. Raja Ampat Islands, West Papua, Indonesia, May 2007

Georgette Douwma / Loki whip goby (Bryaninopss loki) on Sea pen (Virgularia gustaviana). Komodo National Park, Indonesia

Georgette Douwma / Purple sea pen (Virgularia gustaviana) on sandy sea bed. Rinca, Indonesia

Georgette Douwma / Sea pen (Virgularia gustaviana) with a small porcelain crab on sandy sea bed, purple form. Rinca, Indonesia.

Jeff Rotman / Gurney's Sea Pen (Ptilosarcus gurneyi) on sea bed at night, Queen Charlotte Strait, British Columbia, Canada, North Pacific Ocean

Jeff Rotman / Gurney's Sea Pen (Ptilosarcus gurneyi) close up detail, Queen Charlotte Strait, British Columbia, Canada, North Pacific Ocean

Jeff Rotman / Gurney's Sea Pen (Ptilosarcus gurneyi) close up detail, Queen Charlotte Strait, British Columbia, Canada, North Pacific Ocean

Jeff Rotman / Gurney's Sea Pen (Ptilosarcus gurneyi) close up detail, Queen Charlotte Strait, British Columbia, Canada, North Pacific Ocean

Jeff Rotman / Gurney's Sea Pen (Ptilosarcus gurneyi) close up detail, Queen Charlotte Strait, British Columbia, Canada, North Pacific Ocean

David Shale / Sea Pen Pennatulid. Collected from coral sea mount near Dragon vent field on SW Indian Ridge, Indian Ocean.

David Shale / Sea Pen Pennatulid. Collected from coral sea mount near Dragon vent field on SW Indian Ridge, Indian Ocean.

David Shale / Sea pen (Pennatulacea) from coral seamount, SW Indian Ridge, Indian Ocean, December 2011

David Shale / Close up of Sea pen (Pennatulacea) from coral seamount, SW Indian Ridge, Indian Ocean, December 2011

Roland Seitre / Pens and breeding sheds; a location for the breeding and reintroduction program of Iberian / Spanish Lynx (Lynx pardina) in Andalusia. Donana, Spain, June 2006.

Nick Turner / Cotswold Lion rare breed sheep in pens at the Cotswold Farm Show, Cirencester, UK, July 2008.

Nick Turner / Cotswold Lion rare breed sheep in pens at the Cotswold Farm Show, Cirencester, UK, July 2008.

Todd Mintz / Gurney's Sea pen (Ptilosarcus gurneyi) diver in background, Hussar Island, British Columbia, Canada, August

Gary K. Smith / Domestic sheep (Ovis aries) in pens at livestock market awaiting auction, Hawes Mart, Yorkshire, UK, September 2011

Gary K. Smith / Domestic sheep (Ovis aries) in pens at livestock market awaiting sale at auction, Hawes Mart, Yorkshire, UK, September 2011

David Shale / Detail of deepsea Sea pen (Pennatulacea) from coral seamount, Indian Ocean, December 2011

David Shale / Detail of deepsea Sea pen (Pennatulacea) from coral seamount, Indian Ocean, December 2011

David Shale / Detail of deepsea Sea pen (Pennatulacea) from coral seamount, Indian Ocean, December 2011

David Shale / Deepsea Sea pen (Pennatulacea) from coral seamount, Indian Ocean, December 2011

David Shale / Deepsea Sea pen (Pennatulacea) from coral seamount, Indian Ocean, December 2011

David Shale / Detail of deepsea Sea pen (Pennatulacea) from coral seamount, Indian Ocean, December 2011

David Shale / Detail of deepsea Sea pen (Pennatulacea) from coral seamount, Indian Ocean, December 2011

David Shale / Deepsea Sea pen (Pennatulacea) from coral seamount, Indian Ocean, December 2011

Jeff Rotman / Diver examines Giant Gurney's sea pen (Ptilosarcus gurneyi) British Columbia, Canada, North Pacific Model released.

Jeff Rotman / Sea pen (Pteroeides sp) in sand at night, Bismarck Sea, Papua New Guinea

Peter Cairns / 2020VISION / Release pens for White tailed sea eagle chicks (Haliaeetus albicilla) part of the East Scotland Sea Eagle reintroduction project, Fife, Scotland, UK, June 2011.

Peter Cairns / 2020VISION / White tailed sea eagle (Haliaeetus albicilla) release pens, part of the East Scotland Sea Eagle reintroduction project, Fife, Scotland, UK, June 2011

Adrian Davies / Fossil Sea Pen: Charnia masoni. Pre-Cambrian, (more than 560 million years old), found in Newfoundland. Specimen approx 18cm high. Plaster cast.

Juergen Freund / Detail of a Sea Pen showing polyps with eight arms (octocoral) and Brittlestars that have curled themselves around the stem of the sea pen, Palawan, Philippines.

Juergen Freund / Aerial view of fish pens and fish Live reef fish farms in highly populated area of Manila, Philippines, April 2010.

Juergen Freund / Aerial view of large numbers of fish pens choking Malampaya Sound, habitat of the highly endangered Irrawaddy dolphin, Palawan, Philippines, April 2010.

Juergen Freund / Aerial view of grow-out fish pens at fish farm in which line caught fish are grown on for the Live reef fish trade for export, Palawan, Philippines, April 2010.

Juergen Freund / Sea pen (Pteroeides sp) on seabed at night, Komodo NP, Indonesia.

Juergen Freund / Sea pen (Virgularia sp) on sandy seabed, Palawan, Philippines.

Juergen Freund / Sea pen (Pennatulacea) on the sandy bottom with diver in the background, Komodo NP, Indonesia, Indo-pacific.

Juergen Freund / Sea pen porcelain crabs (Porcellanella triloba) in sea pen (Pteroides sp.). Lembeh Strait, North Sulawesi, Indonesia.

David Woodfall / Flock of sheep (Ovis aries) in fold, gathered for marking by community shepherds on steppe as part of a peasant economy. Romania, October 2010

David Woodfall / Flock of sheep (Ovis aries) in fold, gathered for marking by community shepherds on steppe as part of a peasant economy. Romania, October 2010

David Woodfall / Flock of sheep (Ovis aries) in fold, gathered for marking by community shepherds on steppe as part of a peasant economy. Romania, October 2010

Charlie Summers / American Bison (Bison bison) herd being driven from their free range in Custer State Park, to holding pens during the annual Buffalo roundup. The Park Service has learned not to run the herd but they...

Charlie Summers / Cowboys on horseback driving herd of American Bison (Bison bison) into the holding pens at the Buffalo corrals. This event has grown in size now to where some 15,000-20,000 people attend each year. Cu...

Tim Laman / A man tends Grouper holding pens, destined for the live fish trade to Hong Kong. Raja Ampat Islands, West Papua, Indonesia, May 2007

Tim Laman / Captive / farmed Grouper pens, destined for the live fish trade to Hong Kong, and hut of caretaker. Raja Ampat Islands, West Papua, Indonesia, May 2007

Michele Westmorland / Conch (Strombidae) farm, with offshire pens sign. The only farm of its kind in the world. Provodenciales, Turks and Caicos, Caribbean. June 2007

Georgette Douwma / Sea pen (Virgularia gustaviana) on sandy sea bed. Orange form, Rinca, Komodo National Park, Indonesia

Georgette Douwma / Loki whip goby (Bryaninopss loki) on Sea pen (Virgularia gustaviana). Komodo National Park, Indonesia

Georgette Douwma / Purple sea pen (Virgularia gustaviana) with a Commensal shrimp (Periclimenes magnificus) on sandy sea bed. Rinca, Komodo National Park, Indonesia

Georgette Douwma / Sea pen (Pteroeides sp) on sandy sea bed. Komodo National Park, Indonesia

Georgette Douwma / Purple sea pen (Virgularia gustaviana) on sandy sea bed. Orange form, Rinca, Indonesia

Georgette Douwma / Sea pen (Pteroeides sp) on sandy seabed, Komodo National Park, Indonesia

Georgette Douwma / Sea pen (Pteroeides sp) on sandy sea-bed. Komodo National Park, Indonesia

Georgette Douwma / Sea pen (Virgularia gustaviana) on sandy sea bed, purple form, Rinca, Indonesia

Pete Oxford / Flock of Sheep (Roughies) in pens for shearing. Port Stephens Farm. West Falkland. Falkland Islands

Tim Laman / Sea pen (order Pennatulacea) growing on a sandy seabed, Bali, Indonesia.

Tim Laman / Sea Pen (order Pennatulacea) growing on a sandy seabed, Bali, Indonesia.

Sue Daly / Close up of polyps of Gurney's / Orange sea pen (Ptilosarcus gurneyi) Pacific coast, Canada, August

Sue Daly / Orange / Gurney's sea pen (Ptilosarcus gurneyi) Pacific coast, Canada, August

Georgette Douwma / Hydroid or Fairy crab (Hyastenus bispinosus) on Sea pen (Pteroides sp.) where it has climbed to feed on plankton floating past. It has decorated its body with hydroid polyps. Majidae - Spider or Decor...

Jerry Monkman / Salmon pens at Atlantic salmon farm, Cutler, Maine, USA

Georgette Douwma / Nudibranch {Armina sp} feeding on a Sea pen, Rinca, Indonesia

Rolf Nussbaumer / Workers herding Domestic sheep into shearing pens, Hill Country, Texas, USA, April 2007

Pete Oxford / Pig snout peering out under a door - the domestic animals live in pens within the courtyard of the houses. These pigs have chewed through the woodwork so that they can see out. Naxi Village near Lijia...

Pete Oxford / Two Pig snouts peering out under door - the domestic animals live in pens within the courtyard of the houses. These pigs have chewed through the woodwork so that they can see out. Naxi Village near Li...

Doug Wechsler / Gurney's sea pen (Ptilosarcus gurneyi) Puget Sound, Washington, USA

Juergen Freund / Juvenile Giant clams (Tridacna sp) in breeding pens on commerical clam farm, Palau, Micronesia

WILLIAM OSBORN / Pheasant {Phasianus colchicus} breeding pens for game, Glos, UK

Colin Seddon / Dead Tawny Owl {Strix aluco} caught in pole trap near pheasant pens, North Devon, UK

Dan Burton / Salmon farm pens out in water, Narvik, Norway, Europe

David Shale / Sea Pen (Pennatulid), with partially retracted polyps, deep sea Atlantic ocean

David Shale / Sea Pen (Pennatulid), deep sea Atlantic ocean

David Shale / Sea Pen (Pennatulid), deep sea Atlantic ocean

David Kjaer / Release pens for Great Bustard reintroduction prog, Wiltshire, Salisbury plain, 2004

Francis Abbott / Sea pen on sea floor {Sarcoptilus genus} Bahrain Arabian Gulf

GEORGETTE DOUWMA / Sea pen {Pteroeides sp} Sangalaki, Indonesia

GEORGETTE DOUWMA / Sea pen {Pteroeides sp} Sangalaki, Indonesia

Juergen Freund / Sea pen (Pteroeides species} + diver, Sulu-sulawesi seas, Indo Pacific

Onne van der Wal / A child colouring on board a Shannon Shoalsailor yacht, Exuma, Bahamas.

Roberto Rinaldi / A sea pen (Pennatula sp.) on sandy seabed in the coral sea, Flinders Reef, Australia