A Somali police officer arrests a suspected rebel member of the al Qaeda-affiliated al Shabaab among beach goers in Mogadishu. Al Shabaab claimed responsibility for today's pre-dawn attack on a Kenyan university campus near the Somali border. The following gallery examines who is al Shabaab. Here: Somali police officer (R) arrests a suspected rebel member (L) of the Al Qaeda-affiliated al Shabaab among beach goers at the Lido beach north of Somalia's capital Mogadishu March 23, 2012. (Photo by Feisal Omar/Reuters)

An Israeli army officer gives explanations to journalists during an army organised tour in a tunnel said to be used by Palestinian militants for cross-border attacks, July 25, 2014. (Photo by Jack Guez/Reuters)

Policemen and residents run as waves from a tidal bore surge past a barrier on the banks of Qiantang River in Haining, Zhejiang province August 31, 2011. As Typhoon Nanmadol approaches eastern China, the tides and waves in Qiantang River recorded its highest level in 10 years, local media reported. (Photo by Reuters/China Daily)

An Alitalia plane approaches to land as starlings fly at Fiumicino international airport in Rome October 14, 2013. Italy will have to notify a planned government-led 500-million-euro bailout of near-bankrupt airline Alitalia to EU regulators who will then assess whether the measure complies with EU state aid rules, the European Commission said on Monday. (Photo by Max Rossi /Reuters)

Men dressed as soldiers pose with models before the opening of the Gamescom 2013 fair in Cologne,Germany, on August 23, 2013. The Gamescom convention is Europe's largest video games trade fair. (Photo by Ina Fassbender/Reuters)

Sulphur miners haul sulphur up an arduous path out of Indonesia’s Ijen volcano. The average carry out of the volcano is 70 kilograms per load per miner. The all-time record carry was 120 kilograms in one load. Extraordinary numbers given most of the miners only weigh around 55 kilograms. Ijen volcano, Indonesia, 2012. (Photo by Hugh Brown/South West News Service)

Claire and Rupert Callender of the Green Funeral Company pose for a photograph with a environmentally friendly coffin in woodland close to their office at Dartington Hall Estate on February 4, 2011 near Torquay, England. The Devon-based company operates as funeral directors and undertakers throughout the South West, offers an ecological alternative to traditional funerals, with coffins made from ecologically friendly materials such as wicker and bamboo, and can arrange funerals that encompass diverse religious and spiritual beliefs everything from a Catholic Requiem Mass, to a Pagan ritual at a stone circle on Bodmin Moor. (Photo by Matt Cardy/Getty Images)

Among the fish populations that could be harmed by the Xayaburi dam in Laos is the critically endangered Mekong giant catfish, considered by the Guinness Book of World Records to be the world’s largest freshwater fish. The fish, which grows to 650 pounds and about 10 feet long, is only found in the Mekong River. It is migratory, moving between downstream habitats in Cambodia upstream to northern Thailand and Laos each year to spawn. Some experts fear the Xayaburi dam could block the migration and drive the giant catfish to extinction. (Photo by Courtesy of Zeb Hogan/University of Nevada, Reno)